阅读说明：本技术 电压控制振荡器 (Voltage controlled oscillator ) 是由 林纪贤 陈和祥 廖显原 叶子祯 吕盈达 于 2019-06-28 设计创作，主要内容包括：电压控制振荡器包含用以具有电源供应电压的电源供应节点。参考节点用以具有第一参考电压。变压器耦合带通滤波器耦接到一对交叉耦合的晶体管。该对交叉耦合的晶体管和变压器耦合带通滤波器位于电源供应节点与参考节点之间。(The voltage controlled oscillator includes a power supply node to have a power supply voltage. The reference node is used for having a first reference voltage. The transformer coupled bandpass filter is coupled to a pair of cross-coupled transistors. The pair of cross-coupled transistors and the transformer-coupled bandpass filter are located between the power supply node and the reference node.)

1. A voltage controlled oscillator, comprising:

a power supply node for having a power supply voltage;

a reference node for having a first reference voltage;

a pair of cross-coupled transistors; and

a transformer coupled bandpass filter coupled to the pair of cross-coupled transistors,

wherein the pair of cross-coupled transistors and the transformer-coupled bandpass filter are located between the power supply node and the reference node.

Technical Field

The present invention relates to a voltage controlled oscillator, and more particularly, to a voltage controlled oscillator with phase noise suppression.

Background

A voltage controlled oscillator is an oscillator having an output signal whose output can be varied within a range, the range being controlled by an input voltage. The output frequency of the output signal of the oscillator is directly related to the input voltage. The oscillation frequency varies in a range from several hertz to several hundred gigahertz (GHz). The output frequency of the output signal is adjusted by varying the input voltage.

Disclosure of Invention

One embodiment of the present disclosure relates to a voltage controlled oscillator including a power supply node, a reference node, a pair of cross-coupled transistors, and a transformer-coupled bandpass filter. The power supply node is used for having a power supply voltage. The reference node is used for having a first reference voltage. A transformer coupled bandpass filter is coupled to the pair of cross-coupled transistors, wherein the pair of cross-coupled transistors and the transformer coupled bandpass filter are located between the power supply node and the reference node.

Drawings

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying drawing figures. It should be noted that the various features are not drawn to scale in accordance with standard practice in the industry. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion:

FIGS. 1A-1B are schematic diagrams of a voltage controlled oscillator according to an embodiment;

FIGS. 2A-2B are schematic diagrams and graphs illustrating phase noise performance of a voltage controlled oscillator according to one embodiment;

FIG. 3 is a graph of a transmission coefficient of a voltage controlled oscillator according to an embodiment;

FIG. 4 is a schematic diagram of a transformer coupled bandpass filter according to an embodiment;

fig. 5A-5B are schematic diagrams of a transformer coupled bandpass filter according to an embodiment;

6A-6B are schematic diagrams of a transformer coupled bandpass filter and an isolated diagram of a transformer coupled bandpass filter according to an embodiment;

FIG. 7 is a schematic diagram of a transformer coupled bandpass filter according to an embodiment;

FIGS. 8A-8B are graphs of noise suppression of a voltage controlled oscillator according to one embodiment;

FIGS. 9A-9B are graphs of measured oscillation frequency and measured phase noise of a voltage controlled oscillator according to one embodiment; and

fig. 10 is a flow diagram of a method for generating an oscillating signal according to an embodiment.

[ notation ] to show

In order to make the aforementioned and other objects, features, advantages and embodiments of the present invention comprehensible, the following description is given:

100. 202: voltage controlled oscillator

102: resonator having a dielectric layer

104. 108: t-shaped bias circuit/T-shaped bias circuit

106: transformer coupling band-pass filter

BFP: band-pass filter

114. 116, 118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140: node point

144. 146: polar point

L1, L2: inductor

M1, M2, M3, M4: transistor with a metal gate electrode

CR1, CR 2: core(s)

C1、C_c1、C_c2C2, C3, C4, C5, C6: capacitor device

T1, T2: transformer device

W1, W3: primary winding

W2, W4: secondary winding

R1, R2: resistor with a resistor element

V_BUF: DC voltage power supply

V_DD: power supply source

V_G: voltage source

V_ctrl1: a first reference voltage

V_ctrl2: second reference voltage source

204: first band-pass filter

206: output of

208: second band-pass filter

210. G1, G2, D1, D2: signal

212. 214: adder

216. 218: electric conduction device

220. 222: feedback arm

224: phase noise performance/curve

m₁、m₂: gain of

300: graph/curve

302. 204, 606, 608, 804, 806, 906, 908, 910: curve line

400: transformer device

404: first substrate

406. 412, 414, 418: conductive structure

416: second substrate structure

420. 422, 424, 426, 428: : terminal with a terminal body

430. 432: through hole structure

434: first terminal

436: relatively extended part/extended part

438: extension part

500. 502, 600, 604: transformer coupling band-pass filter

602: lowest metal layer

700: transformer coupling band-pass filter/transformer coupling band-pass filter

714. 716: region(s)

800. 802, 902, 904: graph table

1000: method of producing a composite material

1002. 1004, 1006, 1008: : step (ii) of

Detailed Description

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components, values, operations, materials, arrangements, etc. are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. Other components, values, operations, materials, arrangements, etc. are contemplated. For example, forming a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

The voltage controlled oscillator is used as part of a Phase Locked Loop (PLL) to synchronize the voltage controlled oscillator frequency with a reference frequency. The quality of the vco output is compromised when short term random frequency signal fluctuations (referred to as phase noise) occur at the output. Phase noise introduces second and third harmonic spectral components that alter the output of the vco. For voltage controlled oscillators to operate under certain millimeter wave applications (mmWave) (30GHz-300GHz), the voltage controlled oscillator needs to control the amount of phase noise that appears at the voltage controlled oscillator output.

Fig. 1A is a schematic diagram of a voltage controlled oscillator 100 according to an embodiment. The voltage controlled oscillator 100 has two components: the resonator 102 and the transformer are coupled to a bandpass filter 106. The resonator 102 is used for frequency detection and reproduction of the vco 100. The resonator 102 includes two T-bias-tee (bias-T) circuits 104 and 108, which bias- circuit 104 and 108 provide a DC voltage or a DC current to bias the resonator 102. The T-bias circuit 104 includes an inductor L1, a node 114, and a capacitive device C1. Inductor L1 is connected at one end to node 114 and at the other end to a DC voltage supply V_BUF. Capacitive device C1 is connected to node 114 at one terminal and to resistor R1 at the other terminal. Resistor R1 is connected to the ground source at another end point. The T-bias circuit 108 includes an inductor L2, a node 116, and a capacitive device C2. Inductor L2 is connected at one end to node 116 and at the other end to a DC voltage supply V_BUF. Capacitive device C1 is connected at one end to node 116 and at the other end to resistor R2. Resistor R2 is connected to the ground source at another end point. The T- bias circuits 104 and 108 are used to provide a fixed DC voltage to the transistors M3 and M4.

Transistor M3 is connected to node 114 at a drain terminal and to a grounded source at a source terminal. The gate of transistor M3 is connected to node 118. Variable capacitance device C6 is connected at one end to node 118 and at the other end to electrical node 120. Transistor M4 is connected to node 116 at a drain terminal and to a grounded source at a source terminal. The gate of transistor M4 is connected to node 122. Variable capacitance device C3 is connected at one end to node 122 and at the other end to node 120. Node 120 is connected to a first reference voltage V_ctrl1。

The drain terminal of transistor M1 is connected to node 124 and the source terminal is connected to a ground voltage. The drain terminal of transistor M2 is connected to node 126 and the source terminal is connected to a ground voltage. The gate of transistor M1 is connected to node 128, and the gate of transistor M2 is connected to node 130. Variable capacitance device C5 is connected at one end to node 128 and at the other end to node 132. Variable capacitance device C4 is connected at one end to node 130 and at the other end to node 132. Node 132 is connected to a second reference voltage source V_ctrl2. Transistors M1 and M2 are used to form a pair of cross-coupled transistors.

The transformer coupled bandpass filter 106 includes a pair of coupled transformers T1 and T2, and a pair of coupled capacitive devices C_c1And C_c2. Transformer T1 includes a primary winding W1, a secondary winding W2, and a core CR 1. Transformer T2 includes a primary winding W3, a secondary winding W4, and a core CR 2. Transformers T1 and T2 are intended to operate together in this embodiment as a 1:2 transformer, however, in other embodiments, transformers T1 and T2 have different transformer implementations depending on the power considerations of the vco. The transformer T1 generates a phase difference of 180 degrees as shown by the polarity point 144 of the transformer T1, and is mounted by the transformerSetting T2 results in a phase of-180 degrees, as shown by polarity point 146. Primary winding W1 is connected at one end to node 134 and at the other end to power supply V_DDAnd primary winding W3 is connected at one end to node 136 and at the other end to power supply V_DD. Capacitor device C_c1Connected between nodes 134 and 136. Secondary winding W2 is connected at one end to node 138 and at the other end to voltage source V_GAnd a secondary winding W4 is connected at one end to node 140 and at the other end to a voltage source V_G. Capacitor device C_c2Is connected between nodes 138 and 140. The pair of coupled capacitor devices C_c1And C_c2The coupling with transformers T1 and T2 forms a bandpass filter.

The connection of node 134 to node 124, node 136 to node 130, node 138 to node 128, and node 140 to node 126 connects the resonator component 102 to the transformer coupled bandpass filter 106.

FIG. 1B is a schematic diagram of the VCO 110 according to one embodiment. The voltage controlled oscillator 110 includes a resonator component 102. The vco 110 differs from the vco 100 in the configuration of the transformer coupled bandpass filter 112 connected to the vco 110. The transformer coupled bandpass filter 112 is similar to the transformer coupled bandpass filter 106, except for the pair of coupled capacitive means C_c1And C_c2The connection mode of (3). In the voltage controlled oscillator 110, a capacitive device C_c1Connected between node 134 and node 138, and capacitive means C_c2Is connected between node 136 and node 140. Capacitor device C of voltage controlled oscillator 110_c1And C_c2Are connected to the same terminals of the transformers T1 and T2, which are connected to the capacitor C of the vco 100_c1And C_c2The opposite is true.

The pair of cross-coupled transistors M1 and M2 are used to create a negative resistance to compensate for signal loss from the transformer coupled bandpass filter 106. Transistors M1 and M2 operate in the saturation region for current stabilityTo reduce 1/f (also referred to as flicker noise) caused by charge trapping and discharging in transistors M1 and M2; however, removing the flicker noise does not reduce the phase noise. Flicker noise is not the dominant factor in higher frequency ranges, such as 1GHz or higher, where phase noise is more dominant. To reduce phase noise, transformer coupled bandpass filters 106 and 112 use a pair of coupled capacitive devices C_c1And C_c2To filter and reduce harmonics of higher harmonics (such as 2 f)₀、3f₀Or higher harmonics) of the phase noise, wherein f₀Is the lower cutoff frequency limit of the transformer coupled bandpass filter 106 or 112 described herein. Capacitor device C_c1And C_c2Each coupled to the pair of coupled transformers T1 and T2 to form transformer coupled bandpass filters 106 or 112. The frequency response of the transformer coupled bandpass filter 106 or 112 contains an additional transmission zero, which is defined as the frequency at which the frequency response yields a value of almost zero. Capacitive means, such as C_c1And C_c2The number of transmission nulls in the system frequency response is increased due to the filtering. The transmission zero of the transformer coupled bandpass filter 106 or 112 occurs at twice the lower limit of the cut-off frequency (2 f)₀) Wherein the lower limit of the cut-off frequency (f)₀) Is the lowest corner frequency of the transformer coupled bandpass filter 106 or 112. In addition, the pair of coupled capacitor devices C_c1And C_c2For the transformer coupled bandpass filter to include a bandpass range outside the frequency range of the phase noise contributed by the second and third harmonics. In at least some embodiments, the transformer coupled bandpass filter 106 or 112 reduces phase noise by 14dB or more.

In some embodiments, transistors M1-M4 are bipolar transistors, Field Effect Transistors (FETs), or the like. In some embodiments, transistors M1-M4 are metal-oxide semiconductor field-effect transistors (MOSFETs), such as CMOS, NMOS, PMOS, and the like. In some embodiments, transistors M1-M4 are different types of transistors. In some embodiments, the described grounded source is grounded to the voltage controlled oscillator either externally or internally to the voltage controlled oscillator. In some embodiments, the variable capacitance devices C3-C6 are varactor structures or the like, and the variable capacitance devices C3-C6 allow the capacitance to be changed based on voltage or current.

Fig. 2A is a schematic diagram of a feedback circuit of the vco 202 according to an embodiment. The VCO 202 has a gain m₁The first band-pass filter 204, the first band-pass filter 204 receiving as input the signal D1. The first bandpass filter 204 produces an output 206, which output 206 is a gain m₁The result of the multiplication with the signal D1. Having a gain m₂The second band pass filter 208 receives as input the signal D2. The second band-pass filter 208 generates an output signal 210, the output signal 210 being a gain m₂The result of the multiplication with the signal D2. Adder 212 receives signal 206 and signal D2 as inputs and outputs signal G2. Adder 214 receives signal 210 and signal D1 as inputs and outputs signal G1. Conductance device 216 receives signal G1 as an input and outputs signal D1. Conductance device 218 receives signal G2 as an input and outputs signal D2. The feedback arm (feedback arm)220 is used to include the conductance device 216 and the adder 214, so that the signal D1 produces a consistent result. Feedback arm 222 is configured to include conductance device 218 and adder 212 such that signal D2 produces a consistent result.

In some embodiments, the gain m₁And m₂Associated with the turns ratio of each of the pair of coupled transformers (e.g., "T1" and "T2") as described herein. In some embodiments, the gain m₁And m₂Are the same or different. In some embodiments, conductance devices 216 and 218 are the conductances of each of the pair of coupled transformers T1 and T2 of fig. 1A and 1B. In some embodiments, conductance devices 216 and 218 include circuitry external to voltage controlled oscillator 202.

The band pass filters 204 and 208 pass the gain m₁And m₂Applied to signals D1 and D2 to increase the oscillation amplitude without requiring an additional DC voltage. In this case, the signals D1 and D2 are substantially similar, the gain m being₁And m₂Is the number of 2, and the number of the second,and the turns ratio of the transformer used by the band pass filters 204 and 206 is 2. Furthermore, all parasitic losses are negligible. Using these parameters, the signal power P of the signal G1 is based on the feedback circuit of the VCO 202 and the following equation_G1Signal power P of about signal D1_D1Triple of:

P_D1+m₂P_D2＝P_G1

if P is_D1＝P_D2And m is₁＝m₂＝2

Then P is_G1＝3P_D1。

The noise power is not increased due to the phase noise suppression of the band pass filters 204 and 208. The voltage controlled oscillator 202 produces a phase reduction of about 10log (1/3) ≈ -4.8 dB.

In some embodiments, the turns ratio is higher than 2 and signals D1 and D2 are dissimilar.

FIG. 2B is a graph illustrating phase noise performance 224 of the VCO 202 according to one embodiment. Curve 224 is a phase noise improvement plot in decibels (dB) against turns ratio. As the turns ratio increases, the phase noise improvement increases, i.e., the dB bit decreases, as shown by curve 224.

Fig. 3 is a graph 300 of the transmission coefficient of a voltage controlled oscillator according to an embodiment. The transmission coefficient of the voltage controlled oscillator is indicative of the amplitude and power of the voltage controlled oscillator output. Curve 300 includes curve 302 and curve 304. Curve 302 contains the transmission coefficient versus frequency for a pair of coupled transformers according to the method without a transformer coupled bandpass filter as described herein, and curve 304 contains the transmission coefficient versus frequency for the transformer coupled bandpass filter of fig. 1A or 1B (e.g., "106" or "112"). In this case, the transformer-coupled bandpass filter has a lower cut-off frequency limit (f) of about 28GHz₀). Curve 304 is included at about 56GHz or (2 f)₀) A transmission zero point that is reduced by more than 14dB compared to the same point of curve 302. At 84GHz, curve 304 contains a dip of about 14dB relative to curve 302. The pair of coupled capacitors filters out higher frequency components of phase noise.

Fig. 4 is a schematic diagram of a pair of coupled transformers 400 for use in a transformer coupled bandpass filter according to an embodiment. The pair of coupled transformers 400 is used in two stacked metal layer arrangements. The pair of coupled transformers 400 includes a plurality of conductive structures 406, 412, and 414 formed on a metal layer. Further, the pair of coupled transformers 400 includes a conductive structure 418 formed on a metal layer, the conductive structure 418 having a first terminal 434 at one end of the coupled transformer 400, with two extensions 438 extending from the first terminal 434 to the two terminals 422 and 426 at the opposite end. The extension portion 438 serves as the primary windings W1 and W3 shown in fig. 1A to 1B.

The conductive structure 412 includes a terminal 424 located at one end of the conductive structure 412 and two opposing extensions 436 located at opposing ends of the conductive structure 412. Two opposing extensions 436 extend from the terminal 424. Conductive structure 406 includes a first terminal connected to one of extensions 436 near first terminal 434. Conductive structure 406 includes a terminal 420 at an end opposite the first end. The conductive structure 414 includes a first terminal connected to another one of the extensions 436 of the conductive structure 412 near the first terminal 434. Further, the conductive structure 414 includes a terminal 428 located at an end opposite the first end. Conductive structures 406 and 414 are connected to an extension 436 of conductive structure 412 below first terminal 434.

Via structures 430 and 432 are used to provide the connections needed to form a pair of coupled transformers 400. A portion of the conductive structures 406, 412, 414, and 418 are located over the first substrate 404. Via structure 432 is used to form a connection between conductive structures 406 and 412 to form secondary winding W2 of fig. 1A-1B, and to form a connection between conductive structures 412 and 414 to form secondary winding W4 of fig. 1A-1B. The connections between conductive structure 406 and conductive structure 412 and between conductive structure 414 and conductive structure 412 are located under the first terminal. Other portions of the conductive structures 406, 412, 414, and 418 include terminals 420, 422, 424, 426, and 428, each of the terminals 420, 422, 424, 426, and 428 being located over one of the series of second substrate structures 416. The second substrate structure 416 is individually patterned to have dimensions similar to the terminals 420, 422, 424, 426 and 428. In addition, via structure 430 is used to connect between terminals 420 and 424 and between terminals 424 and 428.

In some embodiments, first substrate 404 and second substrate 416 are separate substrates. In some embodiments, first substrate 404 and second substrate 416 form a single substrate structure. In some embodiments, the first substrate 404 is a silicon (Si) substrate or a metal substrate. In some embodiments, the second substrate 416 is a Si substrate or a metal substrate.

In some embodiments, via structures 430 and 432 are square vias. In some embodiments, the via structures 430 and 432 have an octagonal shape, a hexagonal shape, a rectangular shape, or the like. In some embodiments, via structures 430 and 432 are through silicon vias. In some embodiments, via structures 430 and 432 are holes etched in a metal-filled interlayer dielectric. In some embodiments, via structures 430 and 432 are buried vias. In some embodiments, via structure 430 is different from via structure 432. In some embodiments, via structures 430 and/or 432 are replaced with a layered metal pair to form an interconnect with conductive structures 406, 412, 414, and 418.

Fig. 5A is a schematic diagram of a transformer coupled bandpass filter 500 according to some embodiments. The transformer coupled bandpass filter 500 includes a pair of coupled transformers similar to the pair of coupled transformers 400 of fig. 4. In addition, FIG. 5A includes a pair of coupled capacitive devices C_c1And C_c2Is the same as the coupling arrangement of the transformer coupling bandpass filter 106 in fig. 1A. The first terminal 434 is coupled to a voltage source V_DDAnd input a voltage V_GAre connected to the terminals 424. Coupled capacitive means C_c1Connected at one end to terminal 420 and at the other end to terminal 426. Coupled capacitive means C_c2Connected at one end to terminal 422 and at the other end to terminal 428. Transformer coupled bandpass filter 500 is that of transformer coupled bandpass filter 106 of FIG. 1AOne embodiment.

Fig. 5B is a schematic diagram of a transformer coupled bandpass filter 502 according to an embodiment. The transformer coupled bandpass filter 500 includes a pair of coupled transformers similar to the pair of coupled transformers 400 of fig. 4. Furthermore, the coupling arrangement comprised in FIG. 5B couples the pair of coupled capacitive devices C of the bandpass filter 112 of the transformer in FIG. 1B_c1And C_c2The coupling arrangement is similar. The first terminal 434 is coupled to a voltage source V_DDAnd input a voltage V_GAre connected to the terminals 424. Coupled capacitive means C_c1Connected at one end to terminal 420 and at the other end to terminal 422. Coupled capacitive means C_c2Connected at one end to terminal 426 and at the other end to terminal 428. Transformer coupled bandpass filter 502 is one embodiment of transformer coupled bandpass filter 112 of fig. 1B.

Transformer coupled bandpass filters 500 and 502 have characteristics similar to those described herein with respect to transformer coupled bandpass filters 106 and 112 of fig. 1A and 1B. In particular, transformer coupled bandpass filters 500 and 502 have a transmission zero (2 f) that is twice the lower limit of the cutoff frequency₀). In addition, transformer coupled bandpass filters 500 and 502 filter out phase noise contributed by the second and third harmonics, as described herein.

Fig. 6A is a schematic diagram of a transformer coupled bandpass filter 600 according to some embodiments. The transformer coupled bandpass filter 600 is similar to the transformer coupled bandpass filter 502 described in fig. 5B. FIG. 6A includes a terminal 424 coupled to the lowest metal layer 602, and the pair of capacitive devices C_c1And C_c2Arranged similarly to the transformer coupled bandpass filter 502 of fig. 5B. The metal layer 602 is coupled to a voltage source V_G. In addition, the transformer coupled band pass filter 600 is used to provide isolation against noise generated by parasitic resistance and the like. The ratio of the width between the width W1 of the terminal and the width W2 of the metal layer 602 is related to the increased isolation in the transformer coupled bandpass filter 604.

FIG. 6B is a graph of the isolation control width ratio (W1/W2). The curve 604 includes two curves 606 and 608. Curve 606 contains the isolation comparison width ratio for the transformer coupled bandpass filter operating at 28GHz and curve 608 contains the isolation comparison width ratio for the transformer coupled bandpass filter operating at 56 GHz. The higher the width ratio, the better the isolation, as shown by curves 606 and 608. One way to increase isolation is to reduce the width W2 of the metal layer 602. At 28GHz and 56GHz, a width ratio of 8 or higher is used.

Fig. 7 is a schematic diagram of a transformer coupled bandpass filter 700 according to an embodiment. Transformer coupled bandpass filter 700 is similar to transformer coupled bandpass filter 600 described in fig. 6A. In addition, FIG. 7 includes a pair of coupled capacitive devices C_c1And C_c2The pair of coupled capacitor devices C_c1And C_c2At the lower metal layer below regions 714 and 716 of transformer coupled bandpass filter 700. A capacitor C for coupling the pair_c1And C_c2Capacitive means C placed at the lower metal layer below the transformer allowing the coupling of the pair_c1And C_c2Coupling with the transformer is sufficient separation between the other operational elements of the band pass filter 700. The separation reduces the capacitance means C coupled by_c1And C_c2The parasitic capacitance introduced has an effect on the remaining operational elements of the transformer coupled bandpass filter 700. In addition, the spatial area of the transformer-coupled bandpass filter 700 is reduced. In some embodiments, the pair of coupled capacitive devices under the transformer are formed using a layer of insulator material or the like.

Fig. 8A is a graph 800 of output power of a voltage controlled oscillator according to an embodiment. In particular, graph 800 includes output power versus frequency at a fundamental frequency and several harmonics according to a first voltage controlled oscillator without another method of transformer coupled bandpass filters as described herein and a second voltage controlled oscillator according to a method of transformer coupled bandpass filters as described herein. The fundamental frequency is 28 GHz. At the second harmonic (56GHz), the first voltage controlled oscillator produces a 22dB drop in phase noise and the second voltage controlled oscillator produces a greater 28dB drop. At the third harmonic (84GHz) and the fourth harmonic (112GHz), the second voltage controlled oscillator produces a greater phase noise reduction relative to the first voltage controlled oscillator due to the filtering characteristics of the transformer coupled bandpass filter as described herein.

FIG. 8B is a graph of noise suppression of a voltage controlled oscillator according to one embodiment. In this case, FIG. 8B includes a graph 802, the graph 802 having two curves 804 and 806. Curve 804 is the analog phase noise versus offset frequency for a first voltage controlled oscillator according to another method without a transformer coupled bandpass filter as described herein, and curve 806 is the analog phase noise versus offset frequency for a second voltage controlled oscillator with a transformer coupled bandpass filter as described herein. As shown in FIG. 8B, the phase noise of the second VCO is improved by 6.8dB and 4.6dB at 100kHz and 1MHz offset.

Fig. 9A is a graph 902 of measured oscillation frequency. Graph 902 contains two curves 904 and 906. Curve 904 includes the oscillation frequency versus control voltage V for a voltage controlled oscillator having a transformer coupled bandpass filter as described herein_ctrl2And curve 906 represents the oscillation frequency of the same vco versus the control voltage V_ctrl2The actual measurement of (2). The tuning range shown in curve 902 is between 27.2GHz and 27.7 GHz. The larger the control voltage is increased, the smaller the difference between the analog and measured oscillation frequencies, as shown in fig. 9A.

Fig. 9B is a graph 904 of measured phase noise. Graph 904 includes two curves 908 and 910. Curve 908 is the phase noise measured at 27.4GHz for a first vco according to another method without a transformer coupled bandpass filter as described herein, while curve 910 is the phase noise measured at 27.4GHz for a second vco with a transformer coupled bandpass filter as described herein. The measured phase noise of curve 910 is improved by 5dB compared to the measured phase noise of curve 908. This improvement is consistent with the 4.8dB phase noise reduction discussed in fig. 2A-2B.

FIG. 10 is a flow of a method 1000 for generating an oscillating signal in accordance with one or more embodimentsA flow chart. The method 1000 may be used to generate an oscillating signal with low phase noise. In step 1002, an input voltage, such as V, is received at an input terminal of a transformer coupled bandpass filter (such as terminal 424 of the pair of coupled transformers 400)_G(FIG. 2A).

In step 1004, a power supply voltage, such as V, is received at a power input of a transformer coupled bandpass filter, such as the first terminal 434 of the pair of coupled transformers 400_DD。

In step 1006, a transformer coupled bandpass filter is coupled to a reference voltage (such as V) via a cross-coupled transistor pair (such as M1 and M2)_ctrl2Or V_ctrl1) And (4) coupling. In some embodiments, the transformer coupled bandpass filter includes a pair of coupled transformers having a particular turns ratio. The transformer coupled bandpass filter includes a pair of coupled capacitive devices. In some embodiments, a first capacitive device of the pair of coupled capacitive devices is coupled at one end point to a gate of a first transistor of the pair of cross-coupled transistors and another end point is coupled to a drain of a second transistor of the pair of cross-coupled transistors, and a second capacitive device of the pair of coupled capacitive devices is coupled at one end point to a drain of a first transistor of the pair of cross-coupled transistors and another end point is coupled to a gate of a second transistor of the pair of cross-coupled transistors. In some embodiments, the first capacitive means in the pair of coupled elements is coupled at one end point to the gate of a first transistor in the pair of cross-coupled transistors and another end point is coupled to the drain of the first transistor in the pair of cross-coupled transistors, and the second capacitive means in the pair of coupled capacitive means is coupled at one end point to the gate of a second transistor in the pair of cross-coupled transistors and the another end point is coupled to the drain of the second transistor in the pair of cross-coupled transistors.

In step 1008, an oscillating signal is generated having a frequency that is synchronized with the frequency of the reference voltage.

In some embodiments, a voltage controlled oscillator is provided that includes a power supply node, a reference node, a pair of cross-coupled transistors, and a transformer-coupled bandpass filter. The power supply node is used for having a power supply voltage. The reference node is used for having a first reference voltage. A transformer coupled bandpass filter is coupled to the pair of cross-coupled transistors, wherein the pair of cross-coupled transistors and the transformer coupled bandpass filter are located between the power supply node and the reference node.

In some embodiments, the transformer-coupled bandpass filter includes an input node for receiving a second reference voltage different from the first reference voltage.

In some embodiments, the transformer coupled bandpass filter comprises a pair of coupled transformers having a turns ratio of 1: 2.

In some embodiments, the transformer coupled bandpass filter comprises a pair of coupled capacitive devices.

In some embodiments, the voltage controlled oscillator wherein a first one of the pair of coupled capacitive devices is coupled between a gate of a first one of the pair of cross-coupled transistors and a drain of a second one of the pair of cross-coupled transistors, and a second one of the pair of coupled capacitive devices is coupled between the drain of the first one of the pair of cross-coupled transistors and the gate of the second one of the pair of cross-coupled transistors.

In some embodiments, the voltage controlled oscillator wherein a first capacitive device of the pair of coupled capacitive devices is coupled between a gate and a drain of a first transistor of the pair of cross-coupled transistors and a second capacitive device of the pair of coupled capacitive devices is coupled between a gate and a drain of a second transistor of the pair of cross-coupled transistors.

In some embodiments, the transformer coupled bandpass filter is configured to generate a transmission zero at a frequency substantially equal to twice a lower cutoff frequency limit of the transformer coupled bandpass filter.

In some embodiments, a bandpass filter is provided that includes a first conductive structure, a second conductive structure, a third conductive structure, and a fourth conductive structure. The first conductive structure is located in a first metal layer of an integrated circuit, and the first conductive structure includes a first terminal, a second terminal and a third terminal. The first terminal is at a first end of the first conductive structure, and the second and third terminals are at a second end of the first conductive structure, the second end being opposite the first end of the first conductive structure. The second conductive structure is in the first metal layer, and the second conductive structure comprises an input terminal and a plurality of extending parts. The input terminal is located between the second terminal and the third terminal at a first end of the second conductive structure. The extending portions are located at a second end of the second conductive structure, the second end being opposite to the first end of the second conductive structure, wherein the extending portions extend from the input terminal to the first terminal along opposite directions. The third conductive structure is in the first metal layer, wherein a first end of the third conductive structure is connected to one of the extended portions of the second conductive structure, and a second end of the third conductive structure is located opposite the first end of the third conductive structure, the second end of the third conductive structure defining a fourth terminal. The fourth conductive structure is in the first metal layer, the fourth conductive structure is positioned opposite the third conductive structure, wherein a first end of the fourth conductive structure is connected to another of the extended portions of the second conductive structure, and a second end of the fourth conductive structure is positioned opposite the first end of the fourth conductive structure, the second end of the fourth conductive structure defines a fifth terminal, wherein the second terminal is positioned between the fourth terminal and the input terminal, and the third terminal is positioned between the fifth terminal and the input terminal.

In some embodiments, the bandpass filter further comprises a plurality of vias for electrically connecting the second conductive structure to the third conductive structure and electrically connecting the second conductive structure to the fourth conductive structure.

In some embodiments, the band pass filter wherein the first terminal is coupled to a power supply voltage source.

In some embodiments, the bandpass filter wherein the input terminal is coupled to a second metal layer to reduce parasitic resistance.

In some embodiments, the bandpass filter wherein the second terminal and the fifth terminal are each coupled to a first capacitive device.

In some embodiments, the bandpass filter wherein the third terminal and the fourth terminal are each coupled to a second capacitive device.

In some embodiments, the bandpass filter wherein the second terminal and the fourth terminal are each coupled to a first capacitive device.

In some embodiments, the bandpass filter wherein the third terminal and the fourth terminal are each coupled to a second capacitive device.

In some embodiments, a method for generating an oscillating signal is provided, the method comprising: the method includes receiving an input voltage at an input terminal of a transformer coupled bandpass filter, receiving a power supply voltage at a power supply input of the transformer coupled bandpass filter, coupling the transformer coupled bandpass filter with a reference voltage via a cross-coupled transistor pair, and generating an oscillating signal having a frequency synchronized with the frequency of the reference voltage.

In some embodiments, receiving the input voltage at the input terminal includes coupling the input voltage to a pair of coupled transformers of the transformer coupled bandpass filter.

In some embodiments, receiving the input voltage at the input terminal includes coupling the pair of coupled transformers to a pair of coupled capacitive devices.

In some embodiments, coupling the transformer coupled bandpass filter to the reference voltage includes operating the cross-coupled transistors in a saturation region for current stability.

In some embodiments, generating the oscillating signal comprises reducing the signal having a frequency greater than 2f by the transformer coupled bandpass filter₀Of the frequency component of (a), wherein f₀Is a cut-off frequency lower limit of the transformer coupled bandpass filter.

Another aspect of the present description relates to a method for generating an oscillating signal. The method includes receiving an input voltage at an input terminal of a transformer-coupled bandpass filter. In addition, the method includes receiving a power supply voltage at a power input of a transformer coupled bandpass filter. The transformer coupled bandpass filter is coupled to the reference voltage via a cross-coupled transistor pair. In addition, the method includes generating an oscillating signal having a frequency synchronized with a frequency of the reference voltage.

The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.