阅读说明：本技术 具有非线性组件的分布式放大器 (Distributed amplifier with non-linear components ) 是由 卢卡·皮亚宗 于 2018-04-06 设计创作，主要内容包括：本发明提供了一种分布式放大器,例如,用于光发射器或用于雷达应用。与传统分布式放大器相比,本发明的分布式放大器具有改进的输出匹配组件。具体而言,所述分布式放大器包括：放大部分,具有与AC电压输入相连的输入线路和与负载相连的输出线路。此外,所述分布式放大器包括终接在所述输出线路的非线性组件,所述非线性组件等效于电阻,其电阻值根据所述组件两端的AC电压的增大而增大。(The present invention provides a distributed amplifier, for example for use in optical transmitters or for radar applications. The distributed amplifier of the present invention has improved output matching components compared to conventional distributed amplifiers. Specifically, the distributed amplifier includes: an amplifying section having an input line connected to the AC voltage input and an output line connected to the load. Furthermore, the distributed amplifier comprises a non-linear component terminated at the output line, the non-linear component being equivalent to a resistor, the resistance value of which increases in accordance with an increase in the AC voltage across the component.)

1. A distributed amplifier (100), comprising:

an amplification section (101) having an input line (102) connected to an AC voltage input and an output line (103) connected to a load (104);

-a non-linear component (105) terminating at the output line (103), the non-linear component (105) being equivalent to a resistor, the resistance value of which increases in accordance with an increase in the AC voltage across the component.

2. The distributed amplifier (100) of claim 1,

the nonlinear component (105) has an equivalent resistance value that increases at an AC voltage across the component that is greater than a first threshold voltage.

3. The distributed amplifier (100) of claim 1 or 2,

the nonlinear component (105) has an equivalent resistance value that remains constant at an AC voltage across the component that is less than a second threshold voltage.

4. The distributed amplifier (100) of any of claims 1 to 3,

the nonlinear component (105) is a nonlinear resistor.

5. The distributed amplifier (100) of any of claims 1 to 4,

the non-linear component (105) has a continuous dependence on the AC voltage across the component.

6. The distributed amplifier (100) of any of claims 1 to 5,

the non-linear component (105) comprises a transistor (300), in particular a Field Effect Transistor (FET).

7. The distributed amplifier (100) of claim 6,

the nonlinear component (105) further comprises a first resistor (301) and a second resistor (302).

8. The distributed amplifier (100) of claim 7,

the input end of the transistor (300) is grounded through a capacitor (201), and the output end of the transistor (300) is connected with the amplifying part (101);

the control terminal of the transistor (300) is connected to the input terminal via the first resistor (301) and to the output terminal via the second resistor (302).

9. The distributed amplifier (100) of claim 7,

the input end of the transistor (300) is connected with a DC voltage source (500), and the output end of the transistor (300) is connected with the amplifying part (101);

the control terminal of the transistor (300) is connected to the input terminal via the first resistor (301) and to the output terminal via the second resistor (302).

10. The distributed amplifier (100) of any of claims 7 to 9,

the resistances of the first resistor (301) and the second resistor (302), respectively, are larger than the equivalent resistance of the non-linear component (105).

11. The distributed amplifier (100) of any of claims 1 to 10, wherein the distributed amplifier (100) is implemented in a Monolithic Microwave Integrated Circuit (MMIC).

12. A transmitting device (700), in particular an optical transmitter, characterized by comprising a distributed amplifier (100) according to any one of claims 1 to 10.

13. The transmitting device (700) according to claim 12, further comprising:

an electro-optical modulator (EAM) (701) as the load (104) connected to the AC voltage output (103) of the distributed amplifier (100).

Technical Field

The present invention relates to a distributed amplifier. The invention relates in particular to a component for enhancing the output line terminating at a distributed amplifier, which component is typically implemented by an output matching resistor. For example, the distributed amplifier of the present invention may be used to drive electro-optical modulators (EAMs) in optical transmitters, or may be applied in radar applications.

Background

A conventional distributed amplifier is shown in the block diagram of fig. 8. Consists of three main blocks: an amplifying section, typically consisting of a transistor; an input matching resistor RG terminated at an input line of the distributed amplifier; an output matching resistor RD is terminated at the output line of the distributed amplifier. An output matching resistor RD is usually connected to the capacitor CD to avoid DC power dissipation across the resistor RD. Therefore, the DC power consumption of the distributed amplifier is determined by the current Idd used to bias the transistors that make up the amplification section.

In implementing a conventional distributed amplifier, it is desirable to find an optimal balance between output voltage swing and output return loss requirements for a given DC power consumption.

A scheme that balances the two cases described above is usually chosen to implement a conventional distributed amplifier, i.e. setting RD > RL. In the case where the output return loss is neither completely lost nor zero, the maximum output voltage that can be reached is Vout _ max ═ Idd · (RD// RL), i.e., greater than Idd (RL/2) but less than Idd · RL.

Disclosure of Invention

In view of the above disadvantages and trade-offs, there is a need for an improved conventional distributed amplifier. The objective is to provide a distributed amplifier with an increased maximum output voltage while having an optimized or at least good output return loss. Furthermore, the distortion of the distributed amplifier should be small without affecting the DC power consumption.

In fact, the resistance value of the output matching resistor RD directly affects the maximum output voltage swing that the defined DC power consumption can reach. For example, in the case of RD — RL, where RL is the resistance of the output load connected to the distributed amplifier, a full output return loss is obtained. However, the maximum output voltage that can be reached in this case is Vout _ max ═ Idd · (RL/2).

In contrast, when RD ∞ (i.e., open circuit) is satisfied, there is no output return loss at all, but the maximum output voltage that can be achieved at this time is doubled to Vout _ max ═ Idd · RL.

The amplifiers described below are particularly suitable for transmitters requiring a large wide frequency response, such as transmitters used for optical communications and radar applications. Most advanced optical communication transmitter schemes require amplifiers with matched output impedances. This is because the matching output impedance of the amplifier absorbs reflections from the interconnect between the amplifier itself and the EAM, which can be achieved by bond wires and pads that degrade the quality of the transmitted signal. Also, most advanced radar technologies based on multi-antenna beamforming require amplifiers with matched output impedances to avoid loading effects between antennas.

The invention therefore also provides a transmitter, in particular an optical transmitter and a transmitter for radar applications, wherein the inventive distributed amplifier is used for signal amplification. In particular, the distributed amplifier should provide a matched output impedance in the transmitter in order to obtain a higher performance transmitter for optical communication and radar applications.

The object of the invention is achieved by the solution presented in the appended independent claims. Advantageous implementations of the invention are further defined in the dependent claims.

In particular, the nonlinear component is used to terminate at the output line, rather than the output matching resistor of a conventional distributed amplifier.

A first aspect provides a distributed amplifier comprising: an amplifying section having an input line connected to an AC voltage input and an output line connected to a load; a nonlinear component terminated at the output line, the nonlinear component being equivalent to a resistance whose resistance value increases in accordance with an increase in the AC voltage across the component.

Linear (resistive) components, such as the linear output matching resistors of a conventional distributed amplifier, typically have a constant ratio of voltage to current that is independent of the amplitude of the voltage and current. In contrast, nonlinear (resistive) components, such as the nonlinear components of the distributed amplifier of the first aspect, typically have a ratio of voltage to current that is related to either voltage amplitude or current amplitude. Mathematically, the equivalent resistance value of the non-linear component is a monotonically increasing function of the AC voltage across the non-linear component.

Without affecting the maximum output voltage (as in the conventional distributed amplifier), the non-linear component gives the distributed amplifier of the first aspect a good or even optimized output return loss. Therefore, the distributed amplifier of the first aspect is improved over the conventional distributed amplifier, and can be used to realize a higher-performance transmitter or the like.

It is noted that the load connected to the output line of the amplifying section is not necessarily part of the distributed amplifier. That is, the load may be connected to the amplifying section or may not be connected to the amplifying section. For example, in a transmitter, the load is an EAM connected to the output line.

In an implementation of the first aspect, the nonlinear component has an equivalent resistance value that increases at an AC voltage across the component that is greater than a first threshold voltage.

For example, in one implementation, the nonlinear component may have an equivalent resistance value that is greater than a characteristic impedance of the output line at an AC voltage across the component that is greater than a first threshold voltage.

Here and hereinafter, the characteristic impedance of the output line may be an impedance of an output side component constituting the amplifying section of the distributed amplifier. In one implementation, the characteristic impedance of the output line may be an impedance of an output inductor and an output parasitic capacitor of the amplified portion of the distributed amplifier.

In another implementation form of the first aspect, the nonlinear component has an equivalent resistance value that remains constant at an AC voltage across the component that is less than a second threshold voltage. In one implementation, a constant value of the resistance may be matched to the characteristic impedance of the output line.

In another implementation, the nonlinear component may have an equivalent resistance value that matches the characteristic impedance of the output line at an AC voltage across the component that is less than a second threshold voltage.

That is, the nonlinear component may match the resistance of the output load at smaller voltages and assume a resistance value greater than the resistance of the output load at higher voltages. For example, the equivalent resistance of the nonlinear component may have an exponential characteristic of a larger voltage.

In another implementation form of the first aspect, the nonlinear component is a nonlinear resistor.

This is the simplest implementation of the non-linear component. In this case, the equivalent resistance of the nonlinear component is the resistance value at a given voltage across the component.

In another implementation form of the first aspect, the nonlinear component has a continuous dependence on an AC voltage across the component.

This allows the non-linear components to be implemented in the simplest way. The dependence on the AC voltage can also be very careful, but in this case the implementation of the non-linear components is somewhat complicated.

In another implementation form of the first aspect, the non-linear component comprises a Transistor, in particular a Field Effect Transistor (FET).

However, the transistor may also be based on a Bipolar Junction Transistor (BJT) which yields similar results.

In another implementation form of the first aspect, the nonlinear component further includes a first resistor and a second resistor.

These resistors are used to adjust the equivalent resistance of the non-linear components and load effects can be avoided.

In another implementation form of the first aspect, an input terminal of the transistor is grounded through a capacitor, and an output terminal of the transistor is connected to the amplifying section; the control terminal of the transistor is connected to the input terminal through the first resistor and to the output terminal through the second resistor.

An implementation of a distributed amplifier is provided that is easily used with Monolithic Microwave Integrated Circuit (MMIC) technology.

In another implementation form of the first aspect, an input terminal of the transistor is connected to a DC voltage source, and an output terminal of the transistor is connected to the amplifying section; the control terminal of the transistor is connected to the input terminal through the first resistor and to the output terminal through the second resistor.

This implementation of the distributed amplifier allows avoiding the use of a capacitor connected between the non-linear component and ground.

In another implementation form of the first aspect, the resistances of the first and second resistors are each greater than the equivalent resistance of the nonlinear component.

Thereby avoiding loading effects.

In another implementation form of the first aspect, the distributed amplifier is implemented in an MMIC.

A second aspect provides a transmitting device, in particular an optical transmitter, comprising a distributed amplifier according to the first aspect or any implementation thereof.

The distributed amplifier based on the first aspect may also be used for transmitters facing other applications (not only for radar transmitters, etc.). With the distributed amplifier of the first aspect, better output impedance matching can be achieved, thereby improving the performance of the transmitter.

In another implementation manner of the second aspect, the sending device further includes: an EAM as a load connected to the AC voltage output of the distributed amplifier.

It should be noted that all devices, elements, units and means described in the present application may be implemented in software or hardware elements or any combination thereof. The steps performed by the various entities described in this application and the functions to be performed by the various entities described are intended to mean that the various entities are used to perform the various steps and functions. Even though in the following description of specific embodiments the specific functions or steps to be performed by an external entity are not reflected in the description of specific detailed elements of the entity performing the specific steps or functions, it should be clear to the skilled person that these methods and functions may be implemented in corresponding software or hardware elements, or in any combination of such elements.

Drawings

The foregoing aspects and many of the attendant aspects of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 illustrates a distributed amplifier provided by an embodiment of the present invention;

FIG. 2 illustrates a distributed amplifier provided by an embodiment of the present invention;

FIG. 3 illustrates a distributed amplifier provided by an embodiment of the present invention;

FIG. 4 illustrates an example behavior of the nonlinear components of a distributed amplifier provided by an embodiment of the present invention;

FIG. 5 illustrates a distributed amplifier provided by an embodiment of the present invention;

FIG. 6 illustrates a distributed amplifier provided by an embodiment of the present invention;

fig. 7 shows a transmitter including a distributed amplifier provided by an embodiment of the invention;

fig. 8 shows a conventional distributed amplifier.

Detailed Description

Fig. 1 illustrates a distributed amplifier 100 provided by one embodiment. For example, the distributed amplifier 100 may be used in a transmitter, particularly an optical transmitter for driving an EAM.

The distributed amplifier 100 includes: an amplifying section 101 having an input line 102 connected to an AC voltage input and an output line 103 connected to a load 104. For example, the load 104 may be an EAM in an optical transmitter. Thus, the load 104 is typically not part of the distributed amplifier 100. In particular, the amplification section 101 may be composed of a plurality of transistors, and the amplification section 100 may be implemented as a conventional distributed amplifier.

The distributed amplifier 100 further comprises: a nonlinear component 105 terminating at the output line 103. The non-linear component 105 replaces the output matching resistors in a conventional distributed amplifier (as shown in fig. 8). The non-linear component 105 is equivalent to a resistor whose resistance value increases in accordance with an increase in the AC voltage across the component. For example, the nonlinear component 105 may be a nonlinear resistor whose resistance value varies with the applied AC voltage, or a component including one or more transistors and/or resistors so as to have an equivalent resistance to the nonlinear behavior of the applied AC voltage.

The distributed amplifier 100 of fig. 1 is designed according to a new scheme with non-linear components 105 such that the output voltage swing is larger than in a conventional distributed amplifier without increasing the output return loss.

Fig. 2 shows a distributed amplifier 100 provided by an embodiment, based on the distributed amplifier 100 shown in fig. 1. Identical elements are provided with the same reference numerals and have the same function. In particular, the distributed amplifier 100 shown in fig. 2 further comprises an amplifying section 101, an input line 102, an output line 103 connected to a load 104 and a non-linear component 105, without the conventional output matching resistors.

In fig. 2, the nonlinear component 105 is grounded, in particular, by a capacitor 201 (capacitor CD). I.e. the capacitor CD is connected at the termination of the output line 103 between the non-linear component 105 of the distributed amplifier 100 and ground. The capacitor CD may be part of the distributed amplifier 100. In addition, the distributed amplifier 100 shown in fig. 2 has an input matching resistor RG 202 terminated at the input line 102.

The block diagram of the distributed amplifier 100 shown in fig. 2 includes a non-linear component 105 for replacing the conventionally used output matching resistors. The voltage v1 is the AC voltage across the nonlinear component 105, and the current i1 is the AC current flowing through the nonlinear component 105. Due to the capacitor CD, the DC current flowing through the non-linear component 105 is zero.

In particular, the non-linear component 105 may have an equivalent resistance value that increases at an AC voltage v1 across the component that is greater than the first threshold voltage. For example, the equivalent resistance value may be greater than the characteristic impedance of the output line. For example, the equivalent resistance value may be greater than the resistance RL of the load 104. Furthermore, the non-linear component 105 may have an equivalent resistance value that remains constant at an AC voltage across the component that is less than the second threshold voltage. For example, the equivalent resistance value may be matched to the characteristic impedance of the output line. In one example, the equivalent resistance value may match the resistance RL of the load 104.

In particular, for smaller v1 amplitudes, the constitutive equation of the nonlinear component 105 may be NLRD ═ v1/i1 ═ RL. In this case, NLRD ═ RD (since it is typically chosen for the conventional distributed amplifier of fig. 8). Furthermore, for increased v1 amplitudes, the constitutive equation for the nonlinear component 105 may be NLRD ═ v1/i1 > RL. In this case, NLRD > RD (since it is typically chosen for the conventional distributed amplifier of FIG. 8).

The non-linear behavior of the non-linear component 105 allows to obtain at the same time the same output return loss as the conventional distributed amplifier shown in fig. 8 and a maximum output voltage larger than the conventional distributed amplifier with the same DC power consumption at a smaller signal level. The output return loss at smaller signal levels is usually large enough because the reflected signal of the load resistance RL is usually only a small fraction of the transmitted signal. Furthermore, especially in optical transmitters, the output load (e.g. an Electro-absorption modulated Laser (EML)) also has a non-linear behavior, preventing good output return loss at higher output AC voltage levels of conventional distributed amplifiers.

The most convenient solution for implementing the distributed amplifier 100 proposed by the present invention is shown in fig. 3. In particular, fig. 3 shows a distributed amplifier 100 according to an embodiment of the invention, based on the distributed amplifier 100 shown in fig. 1 and 2. Like elements in fig. 3 and fig. 1 and 2, respectively, bear like reference numerals and are functionally identical.

The nonlinear component 105 in the distributed amplifier 100 shown in fig. 3 is implemented by a transistor 300 (a transistor Q1, here exemplified by a FET) and two resistors 301 and 301 (resistors R1 and R2). The output terminal (here the drain (D) terminal) of transistor Q1 is fully interchangeable with the input terminal (here the source (S) terminal), one of which is connected to capacitor CD and the other of which is connected to the amplification section 101 of the distributed amplifier 100. The control terminal, here exemplified by the gate (G) terminal, is connected to resistors R1 and R2, which may have values much greater than RL. There is no DC current in Q1, R1, R2.

An example of a non-linear i1-v1 curve for a non-linear component 105 that may be employed in the distributed amplifier 100 shown in fig. 3 is shown in fig. 4. The non-linear i1-v1 curve may have hyperbolic tangent behavior and/or may exhibit asymptotic behavior to certain constant i-v curves. In particular, fig. 4 shows that the equivalent resistance of the non-linear component 105 is equivalent to a 50 ohm resistor at a smaller amplitude level v 1. Increasing the v1 amplitude level, the slope of the i1-v1 curve of the nonlinear component 105 changes, at some point equivalent to a 140 ohm resistor. Thus, for example, assuming RL ═ 50 ohms, the distributed amplifier 100 with such nonlinear components 105 can achieve full output return loss, while the maximum output voltage Vout _ max ═ Idd · (50 ohms// 140 ohms) ═ Idd · 37 ohms. In contrast, in the case of a conventional distributed amplifier with complete output return loss, the maximum output voltage is only Vout _ max ═ Idd · (50 ohm// 50 ohm) ═ Idd · 25 ohm. This means that the distributed amplifier 100 provided by the present invention allows the maximum output voltage to be increased by more than 50% compared to a conventional distributed amplifier without reducing the output return loss and with the same DC power consumption.

In general, the distributed amplifier 100 of the present invention allows for a greater maximum output voltage than a conventional distributed amplifier as shown in fig. 8 without reducing the other key performance parameters: DC power consumption, output return loss, gain, bandwidth, input return loss, circuit complexity, integrability, required bias voltage.

Fig. 5 shows a distributed amplifier 100 provided by the embodiment of the present invention, which is based on the distributed amplifier 100 shown in fig. 1, fig. 2 and fig. 3. Identical components are provided with the same reference numerals and have the same function. The distributed amplifier 100 of fig. 5 further comprises an amplifying section 101 and an input matching resistor RG 202 and a non-linear (output matching) component 105, wherein said amplifying section 101 and input matching resistor RG 202 can be implemented in the same way as in a conventional distributed amplifier, for example said non-linear (output matching) component 105 further comprises a transistor 300 (transistor QN +1) and two resistors 301 and 302 (resistors R1 and R2).

The size of the transistor QN +1 that makes up the non-linear element 105 may be selected to achieve a desired output return loss. The values of resistors R1 and R2 may be chosen to be much larger than the output load resistance RL to avoid loading effects. The values of R1 and R2 may be the same or different. Fig. 5 is in particular a simple way of constructing the distributed amplifier 100 such that said distributed amplifier 100 can be fully and simply integrated in MMIC technology.

Fig. 6 shows a distributed amplifier 100 provided by an embodiment of the present invention, which is based on the distributed amplifier 100 shown in fig. 1, 2 and 3, and is used to replace the distributed amplifier 100 shown in fig. 5. In this implementation of the distributed amplifier 100, the two terminals of the non-linear component 105 are connected to the VDD voltage source from a DC perspective. This connection avoids the use of capacitor CD (as shown in fig. 5).

In fig. 5 and 6, distributed amplifier 100 includes a plurality of inductors labeled LG1, LG2 … … LGN +1 and corresponding LD1, LD2 … … LDN +1, respectively. Specifically, inductors LD1, LD2 … … LDN +1 are connected in series on output line 103 between load 104 and nonlinear component 500. Specifically, inductors LG1, LG2 … … LGN +1 are connected in series on input line 102 between input matching resistor 202 and voltage input (Vin). Further, distributed amplifier 100 includes a plurality of parallel transistors 302. The transistors are labeled Q1, Q2 … … QN, and are denoted herein as FETs. However, the transistor may also be a BJT. It is noted that N is a natural number. The output D of the transistor (the "drain" of the FET, the "controller" of the BJT) is connected to an output line 103. Specifically, the output terminal D of each transistor is connected to the output line 102 between two of the inductors LD1, LD2 … … LDN + 1. The control terminal G of the transistor (the "gate" of the FET, the "base" of the BJT) is connected to the input line 102. Specifically, the control terminal G of each transistor is connected to the input line 103 between two of the inductors LG1, LG2 … … LGN + 1. The input terminals S of the transistors (the "sources" of the FETs, the "emitters" of the BJTs) are all connected to ground.

Fig. 7 illustrates a transmitting apparatus 700 according to an embodiment of the present invention. The transmitting device 700 may specifically be a light emitter for optical communication or a transmitter for radar applications. In any case, the transmitting apparatus 700 includes the distributed amplifier 100 provided by the embodiment of the present invention. The distributed amplifier 100 may be specifically as shown in fig. 1, fig. 2, fig. 3, fig. 5, or fig. 6.

If the transmitting device 700 is an optical transmitter, an electronic EAM701 may also be included as a load 104, i.e. the EAM701 is connected to the AC voltage output line 103 of the distributed amplifier 100. In fig. 7, the EAM701 is shown in dashed lines, as it is not necessary for the sending device 700 and may be a different type of load 104.

The present invention has been described in connection with various embodiments and implementations as examples. Other variations will become apparent to those skilled in the art upon a study of the drawings, the disclosure, and the appended claims. In the claims as well as in the description, the word "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality of elements or steps. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.