阅读说明：本技术 锁存器电路 (Latch circuit ) 是由 林见儒 雷良焕 于 2018-11-08 设计创作，主要内容包括：一种锁存器电路,包含输入电路、输出电路和开关电路。输入电路用于接收时钟信号和数据信号。输出电路耦接于输入电路,并耦接于第一电源端和第二电源端之间,用于依据时钟信号和数据信号产生输出信号。开关电路耦接于输出电路,其中当数据信号的电压电平切换时,开关电路断开第一电源端和第二电源端之间的导电路径。(A latch circuit includes an input circuit, an output circuit, and a switching circuit. The input circuit is used for receiving a clock signal and a data signal. The output circuit is coupled to the input circuit, coupled between the first power source terminal and the second power source terminal, and configured to generate an output signal according to the clock signal and the data signal. The switching circuit is coupled to the output circuit, wherein the switching circuit breaks a conductive path between the first power source terminal and the second power source terminal when a voltage level of the data signal is switched.)

1. A latch circuit, comprising:

a switch circuit, coupled between a first power source terminal and a second power source terminal, including a positive phase output terminal and a negative phase output terminal;

an input circuit, coupled to the forward output terminal and the reverse output terminal, for receiving a clock signal and a data signal, and for turning on the forward output terminal and the second power terminal according to the clock signal and the data signal; and

the output circuit is coupled to the positive phase output end and the negative phase output end, coupled to the first power end and the second power end, and used for conducting the positive phase output end and the first power end according to the clock signal and the data signal so as to generate an output signal at the positive phase output end;

wherein the switching circuit breaks an electrically conductive path between the first power supply terminal and the second power supply terminal when the voltage level of the data signal switches.

2. The latch circuit of claim 1, wherein the output circuit is further configured to generate an inverted output signal that is inverted with respect to the output signal,

wherein the output circuit controls a cross point of the output signal and the inverted output signal when the voltage level of the clock signal is switched.

3. The latch circuit of claim 1, wherein the output circuit comprises:

a first transistor coupled between the first power terminal and a first node, and having a control terminal coupled to the positive phase output terminal;

a second transistor, coupled between the first power terminal and a second node, and having a control terminal coupled to the inverted output terminal;

a third transistor, coupled between the second power terminal and a third node, and having a control terminal coupled to the positive phase output terminal; and

a fourth transistor, coupled between the second power terminal and a fourth node, and having a control terminal coupled to the inverted output terminal.

4. The latch circuit of claim 3, wherein the switch circuit comprises:

a fifth transistor, coupled between the first node and the inverted output terminal, and having a control terminal for receiving the data signal;

a sixth transistor, coupled between the second node and the positive phase output terminal, having a control terminal for receiving an inverted data signal inverted from the data signal;

a seventh transistor, coupled between the third node and the inverted output terminal, having a control terminal for receiving an inverted clock signal inverted from the clock signal; and

an eighth transistor, coupled between the fourth node and the positive phase output terminal, having a control terminal for receiving the inverted clock signal.

5. The latch circuit of claim 1, wherein the output circuit comprises:

a first transistor coupled between a first node and the inverted output terminal, and having a control terminal coupled to the normal output terminal;

a second transistor coupled between a second node and the positive phase output terminal, and having a control terminal coupled to the negative phase output terminal;

a third transistor coupled between a third node and the inverted output terminal, and having a control terminal coupled to the non-inverted output terminal; and

a fourth transistor coupled between a fourth node and the positive phase output terminal, and having a control terminal coupled to the negative phase output terminal.

6. The latch circuit of claim 5, wherein the switch circuit comprises:

a fifth transistor, coupled between the first node and the first power terminal, and having a control terminal for receiving the data signal;

a sixth transistor, coupled between the second node and the first power terminal, having a control terminal for receiving an inverted data signal inverted from the data signal;

a seventh transistor, coupled between the third node and the second power terminal, having a control terminal for receiving the clock signal; and

an eighth transistor, coupled between the fourth node and the second power terminal, having a control terminal for receiving the clock signal.

7. A latch circuit as claimed in claim 3 or 5, wherein the output circuit is further arranged to generate an inverted output signal which is inverted with respect to the output signal,

wherein the output signal rises to a cross point of the output signal and the inverted output signal over a time period negatively related to an aspect ratio of the second transistor when the voltage level of the clock signal switches.

8. A latch circuit as claimed in claim 4 or 6, wherein the input circuit comprises:

a ninth transistor, a control terminal of which is used for receiving the clock signal;

a tenth transistor having a control terminal for receiving the data signal, wherein the ninth transistor and the tenth transistor are serially connected between the inverted output terminal and the second power terminal;

an eleventh transistor, a control terminal of which is used for receiving the clock signal; and

a twelfth transistor having a control terminal for receiving the inverted data signal, wherein the eleventh transistor and the twelfth transistor are serially connected between the non-inverting output terminal and the second power terminal.

9. A latch circuit as claimed in claim 8, wherein the fifth transistor switches to an off state to break the conductive path before the ninth transistor switches to an on state.

10. The latch circuit of claim 8 wherein the data signal is switched from a first low voltage level to a first high voltage level before the clock signal is switched from a second low voltage level to a second high voltage level.

Technical Field

The present disclosure relates to a latch circuit, and more particularly, to a latch circuit having a switch circuit capable of preventing a short-circuit current.

Background

When the output signal of the conventional latch circuit is transited (e.g., from a value of 1 to a value of 0), the coupled high voltage source and low voltage source are conducted to each other, thereby generating a short-circuit current. The short circuit current may cause ripple (ripple) in the output signal, which may damage components of the back-end circuit (e.g., digital-to-analog converter). In addition, the ripple causes a signal to noise ratio (signal to noise ratio) to decrease, and a total harmonic distortion (total harmonic distortion) to increase.

Disclosure of Invention

The present disclosure provides a latch circuit including an input circuit, an output circuit, and a switch circuit. The input circuit is used for receiving a clock signal and a data signal. The output circuit is coupled to the input circuit, coupled between the first power source terminal and the second power source terminal, and configured to generate an output signal according to the clock signal and the data signal. The switching circuit is coupled to the output circuit, wherein the switching circuit breaks a conductive path between the first power source terminal and the second power source terminal when a voltage level of the data signal is switched.

The latch circuit can improve the signal-to-noise ratio and reduce the total harmonic distortion.

Drawings

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

fig. 1 is a simplified functional block diagram of a digital-to-analog conversion unit according to an embodiment of the disclosure.

Fig. 2 is a circuit schematic of a latch circuit according to an embodiment of the present disclosure.

FIG. 3 is a simplified timing diagram of an embodiment of an operation of the latch circuit of FIG. 2.

Fig. 4 is a partially enlarged timing variation diagram of the first transition stage.

Fig. 5 is a circuit schematic of a latch circuit according to another embodiment of the present disclosure.

Detailed Description

The embodiments of the present disclosure will be described with reference to the accompanying drawings. In the drawings, the same reference numbers indicate the same or similar elements or process flows.

Fig. 1 is a simplified functional block diagram of a digital-to-analog conversion unit 100 according to an embodiment of the disclosure. The digital-analog conversion unit 100 includes latch circuits 110 and 120 and a digital-analog converter 130. The digital-to-analog converter 130 includes current sources Iref1 and Iref2, P-type transistors P1 and P2, and N-type transistors N1 and N2. Transistors P1 and N1 are disposed in series between current sources Iref1 and Iref2, and transistors P2 and N2 are also disposed in series between current sources Iref1 and Iref 2. For simplicity and ease of illustration, other elements and connections in the digital-to-analog converter unit 100 are not shown in fig. 1.

The latch circuit 110 is used for controlling the switching operation of the transistors P1 and P2 according to the data signal Din. The latch circuit 120 is used for controlling the switching operations of the transistors N1 and N2 according to the data signal Din. Through the cooperative operation of the latch circuit 110 and the latch circuit 120, the digital-analog converter 130 may output the feedback signal Fb from between the transistors P1 and N1 and output the inverted feedback signal Fp from between the transistors P2 and N2.

In practice, the digital-to-analog conversion unit 100 can be applied to an analog-to-digital converter. The data signal Din may be generated by an analog-to-digital converter using various dynamic element matching (dynamic element matching) algorithms. The analog-to-digital converter can adjust the output thereof according to the feedback signal Fb and the inverted feedback signal Fp so as to reduce the output error caused by element mismatch.

Fig. 2 is a circuit diagram of a latch circuit 200 according to an embodiment of the disclosure. Latch circuit 200 may be latch circuit 110 or latch circuit 120 of fig. 1. The latch circuit 200 includes an input circuit 210, an output circuit 220, and a switch circuit 230. The switch circuit 230 is coupled between the first power terminal Vn1 and the second power terminal Vn2, and includes a positive phase output terminal Q and a negative phase output terminal QB. The input circuit 210 is coupled to the positive output terminal Q and the negative output terminal QB, for receiving the clock signal Clk and the data signal Din, and for turning on the positive output terminal Q and the second power terminal Vn2 according to the clock signal Clk and the data signal Din. The output circuit 220 is coupled to the positive phase output terminal Q and the negative phase output terminal QB, and coupled to the first power terminal Vn1 and the second power terminal Vn2, for turning on the positive phase output terminal Q and the first power terminal Vn1 according to the clock signal Clk and the data signal Din, So as to generate the output signal So at the positive phase output terminal Q.

In addition, the latch circuit 200 receives a first reference voltage VDD from the first power terminal Vn1 and a second reference voltage VSS from the second power terminal Vn2, wherein the first reference voltage VDD is greater than the second reference voltage VSS.

The output circuit 220 includes first to fourth transistors M1-M4. The first transistor M1 is coupled between the first power terminal Vn1 and the first node N1, and has a control terminal coupled to the non-inverting output terminal Q. The second transistor M2 is coupled between the first power terminal Vn1 and the second node N2, and has a control terminal coupled to the inverted output terminal QB. The third transistor M3 is coupled between the second power terminal Vn2 and the third node N3, and has a control terminal coupled to the non-inverting output terminal Q. The fourth transistor M4 is coupled between the second power terminal Vn2 and the fourth node N4, and has a control terminal coupled to the inverted output terminal QB.

The output circuit 220 outputs an output signal So through the non-inverting output terminal Q and outputs an inverting output signal Sb through the inverting output terminal QB, wherein the phases of the output signal So and the inverting output signal Sb are opposite to each other.

The switch circuit 230 includes fifth to eighth transistors M5 to M8. The fifth transistor M5 is coupled between the first node N1 and the inverted output terminal QB, and has a control terminal for receiving the data signal Din. The sixth transistor M6 is coupled between the second node N2 and the non-inverted output terminal Q, and has a control terminal for receiving the inverted data signal Dip, wherein the phases of the data signal Din and the inverted data signal Dip are opposite to each other. The seventh transistor M7 is coupled between the third node N3 and the inverted output terminal QB, and has a control terminal for receiving the inverted clock signal Clkb, wherein the phases of the clock signal Clk and the inverted clock signal Clkb are opposite to each other. The eighth transistor M8 is coupled between the fourth node N4 and the non-inverting output terminal Q, and has a control terminal for receiving the inverted clock signal Clkb.

The input circuit 210 includes ninth to twelfth transistors M9 to M12. The ninth transistor M9 is coupled between the inverted output terminal QB and the fifth node N5, and has a control terminal for receiving the clock signal Clk. The tenth transistor M10 is coupled between the fifth node N5 and the second power terminal Vn2, and has a control terminal for receiving the data signal Din. The eleventh transistor M11 is coupled between the non-inverting output terminal Q and the sixth node N6, and has a control terminal for receiving the clock signal Clk. The twelfth transistor M12 is coupled between the sixth node N6 and the second power terminal Vn2, and has a control terminal for receiving the inverted data signal Dip.

In other words, the ninth transistor M9 and the tenth transistor M10 are disposed in series between the inverting output terminal QB and the second power terminal Vn2, and the eleventh transistor M11 and the twelfth transistor M12 are disposed in series between the non-inverting output terminal Q and the second power terminal Vn 2.

In some embodiments, the positions of the ninth transistor M9 and the tenth transistor M10 may be interchanged with each other, and the positions of the eleventh transistor M11 and the twelfth transistor M12 may also be interchanged with each other.

In practice, the first transistor M1, the second transistor M2, the fifth transistor M5, and the sixth transistor M6 may be implemented with various suitable P-type transistors. The third transistor M3, the fourth transistor M4, and the seventh through twelfth transistors M7 through M12 may be implemented by various suitable N-type transistors.

FIG. 3 is a timing diagram of an embodiment of the operation of the latch circuit 200 of FIG. 2. In the first transition phase TR1, it is assumed that the latch circuit 200 generates the output signal So equal to the second reference voltage VSS and the inverted output signal Sb equal to the first reference voltage VDD in advance (i.e., the latch circuit 200 stores a value 0 at the non-inverting output terminal Q and a value 1 at the inverting output terminal QB in advance).

When the data signal Din is switched from the first low level L1 to the first high level H1, the clock signal Clk is maintained at the second low level L2. At this time, the first transistor M1, the fourth transistor M4, the sixth transistor M6, the seventh transistor M7, the eighth transistor M8, the tenth transistor M10, and the eleventh transistor M11 are turned on, and the second transistor M2, the third transistor M3, the fifth transistor M5, the ninth transistor M9, and the twelfth transistor M12 are turned off.

Then, the clock signal Clk is switched from the second low voltage level L2 to the second high voltage level H2. Therefore, the ninth transistor M9 and the eleventh transistor M11 are switched to the on state, and the seventh transistor M7 and the eighth transistor M8 are switched to the off state. Therefore, the inverted output signal Sb of the inverted output terminal QB is equal to the second reference voltage VSS, So that the output signal So of the non-inverting output terminal Q is equal to the first reference voltage VDD (i.e., the non-inverting output terminal Q outputs a value 1, and the inverted output terminal QB outputs a value 0).

In other words, the data signal Din is switched from the first low voltage level L1 to the first high voltage level H1 before the clock signal Clk is switched from the second low voltage level L2 to the second high voltage level H2.

Therefore, the fifth transistor M5 is switched to the off state first, and the ninth transistor M9 is switched to the on state, so that the conducting path from the first power terminal Vn1 to the second power terminal Vn2 is kept open during the first transition period TR 1. Thus, a short-circuit current flowing from the first power terminal Vn1 to the second power terminal Vn2 is prevented.

In the first sustain phase TH1, the data signal Din is maintained at the first high voltage level H1. At this time, even though the clock signal Clk switches its voltage level, the output signal So is maintained at the first reference voltage VDD, and the inverted output signal Sb is maintained at the second reference voltage VSS (i.e., the positive phase output terminal Q stores a value 1 and the inverted output terminal QB stores a value 0).

In the second transition period TR2, when the data signal Din is switched from the first high voltage level H1 to the first low voltage level L1, the clock signal Clk is maintained at the second low voltage level L2. At this time, the second transistor M2, the third transistor M3, the fifth transistor M5, the seventh transistor M7, the eighth transistor M8, and the twelfth transistor M12 are in an on state, and the first transistor M1, the fourth transistor M4, the sixth transistor M6, the ninth transistor M9, the tenth transistor M10, and the eleventh transistor M11 are in an off state.

Then, the clock signal Clk is switched from the second low voltage level L2 to the second high voltage level H2. Therefore, the ninth transistor M9 and the eleventh transistor M11 are switched to the on state, and the seventh transistor M7 and the eighth transistor M8 are switched to the off state. Therefore, the output signal So of the positive phase output terminal Q is equal to the second reference voltage VSS, such that the inverted output signal Sb of the inverted output terminal QB is equal to the first reference voltage VDD (i.e., the positive phase output terminal Q outputs a value 0 and the inverted output terminal QB outputs a value 1).

In other words, the data signal Din is switched from the first high voltage level H1 to the first low voltage level L1 before the clock signal Clk is switched from the second low voltage level L2 to the second high voltage level H2.

Therefore, the sixth transistor M6 is switched to the off state first, and the eleventh transistor M11 is switched to the on state, so that the conducting path from the first power terminal Vn1 to the second power terminal Vn2 is kept open during the second transition period TR 2. Thus, a short-circuit current flowing from the first power terminal Vn1 to the second power terminal Vn2 is prevented.

In addition, in the second transition period TR2, after the voltage of the data signal Din changes and before the voltage of the clock signal Clk changes, the non-inverting output terminal Q is in a floating state for a short time because the sixth transistor M6 is switched to an off state. However, since the latch circuit 200 operates at a high frequency, the parasitic capacitance of the positive phase output terminal Q is sufficient to maintain the voltage level of the positive phase output terminal Q when it is floating. Therefore, the output signal So can still be stably maintained at the first reference voltage VDD (i.e., the non-inverting output terminal Q can still stably store the value 1).

In the second sustain period TH2, the data signal Din is maintained at the first low voltage level L1. At this time, even though the clock signal Clk switches its voltage level, the output signal So is maintained at the second reference voltage VSS, and the inverted output signal Sb is maintained at the first reference voltage VDD (i.e., the positive phase output terminal Q stores a value 0 and the inverted output terminal QB stores a value 1).

In the present embodiment, the position of the cross point (cross point) of the output signal So and the inverted output signal Sb can be controlled by adjusting the width-to-length ratio of the first transistor M1 and/or the second transistor M2, and the following description will be made with reference to fig. 2 and fig. 4. Fig. 4 is a partially enlarged timing diagram of the first transition phase TR 1. As described above, in the first transition stage TR1, when the voltage level of the clock signal Clk is switched such that the voltage variation of the inverted output signal Sb is transmitted to the control terminal of the second transistor M2, the second transistor M2 is switched to the conducting state to charge the positive output terminal Q.

By adjusting the width-to-length ratio (width-to-length ratio) of the second transistor M2, the reaction time required for the second transistor M2 to switch from the off state to the on state and the charging speed of the second transistor M2 to the positive phase output terminal Q can be controlled. In detail, the reaction time and the charging speed of the second transistor M2 are both inversely related to the width-to-length ratio of the second transistor M2.

Therefore, in the first transition stage TR1, when the voltage level of the clock signal Clk is switched, the time length T1 required for the output signal So to rise to the crossing point is inversely related to the width-to-length ratio of the second transistor T2.

Similarly, in the second transition period TR2, when the voltage level of the clock signal Clk switches, the length of time required for the inverted output signal Sb to rise to the crossing point is inversely related to the width-to-length ratio of the first transistor T1.

If the latch circuit 200 is the latch circuit 110 for controlling the transistors P1 and P2, the intersection of the output signal So and the inverted output signal Sb may be set lower than the intermediate voltage (e.g., 0.5V) shown in fig. 4. Thus, it is ensured that the transistors P1 and P2 are not turned off at the same time, so as to maintain the stability of the digital-to-analog converter 130.

Similarly, if latch circuit 200 is latch circuit 120 for controlling transistors N1 and N2, the intersection of output signal So and inverted output signal Sb may be set higher than the intermediate voltage value shown in FIG. 4. Thus, it is ensured that the transistors N1 and N2 are not turned off at the same time.

Fig. 5 is a circuit schematic of a latch circuit 500 according to another embodiment of the present disclosure. Latch circuit 500 may be latch circuit 110 or latch circuit 120 of fig. 1. The latch circuit 500 includes an input circuit 210, an output circuit 520, and a switch circuit 530.

The output circuit 520 includes first to fourth transistors M1 to M4. The first transistor M1 is coupled between the first node N1 and the inverted output terminal QB, and has a control terminal coupled to the non-inverted output terminal Q. The second transistor M2 is coupled between the second node N2 and the non-inverting output terminal Q, and has a control terminal coupled to the inverting output terminal QB. The third transistor M3 is coupled between the third node N3 and the inverted output terminal QB, and has a control terminal coupled to the non-inverted output terminal Q. The fourth transistor M4 is coupled between the fourth node N4 and the non-inverting output terminal Q, and has a control terminal coupled to the inverting output terminal QB.

The switch circuit 530 includes fifth to eighth transistors M5 to M8. The fifth transistor M5 is coupled between the first node N1 and the first power terminal Vn1, and has a control terminal for receiving the data signal Din. The sixth transistor M6 is coupled between the second node N2 and the first power terminal Vn1, and has a control terminal for receiving the inverted data signal Dip. The seventh transistor M7 is coupled between the third node N3 and the second power terminal Vn2, and has a control terminal for receiving the inverted clock signal Clkb. The eighth transistor M8 is coupled between the fourth node N4 and the second power terminal Vn2, and has a control terminal for receiving the inverted clock signal Clkb.

The operation and advantages of the latch circuit 500 and the connection of other elements are similar to those of the latch circuit 200, and for brevity, are not repeated herein.

In summary, the latch circuits 200 and 500 switch the conductive path from the first power supply terminal Vn1 to the second power supply terminal Vn2 to an off state when the voltage level of the data signal Din switches. Therefore, the latch circuits 200 and 500 can prevent the generation of a short-circuit current flowing from the first power source terminal Vn1 to the second power source terminal Vn2 when the non-inverting output terminal Q or the inverting output terminal QB is transited.

In other words, the latch circuit 200, 500 can improve the signal-to-noise ratio and reduce the total harmonic distortion.

Certain terms are used throughout the description and following claims to refer to particular components. However, as one of ordinary skill in the art will appreciate, identical components may be referred to by different names. The description and the claims do not intend to distinguish between components that differ in name but not function. In the description and claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. Also, the term "coupled" as used herein includes any direct or indirect connection. Therefore, if a first element is coupled to a second element, the first element may be directly connected to the second element through an electrical connection or a signal connection such as wireless transmission or optical transmission, or may be indirectly connected to the second element through another element or a connection means.

As used herein, the description of "and/or" includes any combination of one or more of the items listed. In addition, any reference to singular is intended to include the plural unless the specification specifically states otherwise.

The above are only preferred embodiments of the present disclosure, and all equivalent changes and modifications made by the claims of the present disclosure should be covered by the scope of the present disclosure.

Description of the symbols

100: digital-to-analog conversion unit

110. 120, 200: latch circuit

130: digital-to-analog converter

210: input circuit

220. 520, the method comprises the following steps: output circuit

230. 530: switching circuit

Iref1 to Iref 2: current source

M1-M12: first to twelfth transistors

N1-N6: first to sixth nodes

N1, N2, P1, P2: transistor with a metal gate electrode

Clk: clock signal

Clkb: inverted clock signal

Din: data signal

Dip: inverted data signal

Fb: feedback signal

Fp: inverted feedback signal

Q: normal phase output end

QB: inverting output terminal

Vn 1-Vn 2: first power supply terminal to second power supply terminal

VDD: a first reference voltage

VSS: second reference voltage

So: output signal

Sb: inverted output signal

TR 1-TR 2: first to second transition stages

TH 1-TH 2: first maintenance stage to second maintenance stage

T1: length of time

L1-L2: first to second low voltage levels

H1-H2: first to second high voltage levels.