CN116526980A - Cascade operational amplifier of common source based on flip voltage follower current source - Google Patents

Abstract

The invention discloses a cascode operational amplifier based on a flip voltage follower current source, which comprises a flip voltage follower current source structure, a sleeve type cascode structure, a current multiplexing structure, a common mode feedback structure, a circuit bias voltage and a bias current; the current source structure of the flip voltage follower is M ₁ 、M ₂ 、M ₃ And M ₄ The method comprises the steps of carrying out a first treatment on the surface of the The sleeve type common-source common-gate structure is M ₅ 、M ₆ 、M ₇ 、M ₈ 、M ₉ 、M ₁₀ 、M ₁₁ 、M ₁₂ 、M ₁₃ 、V _OUTN And V _OUTP The method comprises the steps of carrying out a first treatment on the surface of the The current multiplexing structure is M ₅ 、M ₆ 、M ₁₁ And M ₁₂ The method comprises the steps of carrying out a first treatment on the surface of the The common mode feedback structure is M ₁₄ 、M ₁₅ 、M ₁₆ 、M ₁₇ 、M ₁₈ 、M ₁₉ 、M ₂₀ 、M ₂₁ And V _CMFB The method comprises the steps of carrying out a first treatment on the surface of the The invention can solve the problems that the dynamic current of the existing sleeve type common-source transport amplifier needs to be determined by means of static current, so that the amplification effect of the operational amplifier is not obvious, the offset risk exists and the dynamic current is small.

Description

Cascade operational amplifier of common source based on flip voltage follower current source

Technical Field

The invention belongs to the technical field of electronics, and particularly relates to a cascode operational amplifier based on a flip voltage follower current source.

Background

The common-source common-gate operational amplifier is also called a cascade amplifier and is cascade of a common-source stage and a common-gate stage, and because the common-source amplifying stage converts a voltage signal into a current signal and the input signal of the common-gate amplifying stage is the current signal, the cascade of the common-source and common-gate amplifying circuits forms a common-source common-gate transport amplifier.

The dynamic current of the existing sleeve type common-source transport amplifier needs to be determined by means of static current, so that the operational amplifier has the problems of unobvious amplification effect, offset risk and small dynamic current.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, the present invention provides a high-gain telescopic cascode operational amplifier, which comprises:

a flip voltage follower current source structure, a sleeve type common source and common gate structure, a current multiplexing structure and a common mode feedback structure;

the flipped voltage follower current source structure includes M ₁ 、M ₂ 、M ₃ And M ₄ The method comprises the steps of carrying out a first treatment on the surface of the The sleeve type common-source common-gate structure comprises M ₅ 、M ₆ 、M ₇ 、M ₈ 、M ₉ 、M ₁₀ 、M ₁₁ 、M ₁₂ 、M ₁₃ 、V _OUTN And V _OUTP The method comprises the steps of carrying out a first treatment on the surface of the The current multiplexing structure comprises M ₅ 、M ₆ 、M ₁₁ And M ₁₂ The method comprises the steps of carrying out a first treatment on the surface of the The common mode feedback structure is M ₁₄ 、M ₁₅ 、M ₁₆ 、M ₁₇ 、M ₁₈ 、M ₁₉ 、M ₂₀ 、M ₂₁ And V _CMFB The method comprises the steps of carrying out a first treatment on the surface of the The M is ₁ And M is as follows ₃ 、M ₅ 、M ₇ 、M ₉ 、M ₁₁ 、M ₁₃ Connecting; the M is ₂ And M is as follows ₄ 、M ₆ 、M ₈ 、M ₁₀ 、M ₁₂ 、M ₁₃ Connecting; the M is ₁₃ Grounding; the M is ₁ And M is as follows ₂ Are all connected to a power supply V _DD The method comprises the steps of carrying out a first treatment on the surface of the The M is ₇ And M is as follows ₈ Connected with bias voltage V _BP1 The method comprises the steps of carrying out a first treatment on the surface of the The M is ₉ And M is as follows ₁₀ Connected with bias voltage V _BN The method comprises the steps of carrying out a first treatment on the surface of the The M is ₁₃ Connected with bias voltage V _CMFB 。

Preferably, said M ₁ -M ₄ Is an NMOS tube; wherein the M ₃ -M ₄ For inputting a voltage; m of the flip-flop structure ₁ Or M ₂ The current being fixed by respective bias currents, the bias currents first passing through M ₁ Or M ₂ Then output M ₁ Or M ₂ Voltage, M generated compared with conventional operational amplifier ₁ Or M ₂ The current is not affected by the bias current, and a larger current can be output.

Preferably, said M ₅ -M ₈ Is a PMOS tube; wherein the M ₅ And M ₆ For inputting voltage, M ₇ -M ₈ For a load; the M is ₉ -M ₁₂ Is an NMOS tube; wherein the M ₁₁ And M ₁₂ For inputting voltage, M ₉ -M ₁₀ For a load; the M is ₁₃ Providing feedback for the voltage-controlled current source, and keeping the output common mode level constant; the V is _OUTN And V _OUTP For outputting a voltage.

Preferably, said M ₅ And M ₆ Is a PMOS tube; wherein the M ₅ And M ₆ For inputting a voltage; the M is ₁₁ And M ₁₂ Is an NMOS tube; wherein the M ₁₁ And M ₁₂ For inputting a voltage. M of input signal to the operational amplifier ₅ 、M ₆ 、M ₁₁ 、M ₁₂ When the M is ₅ And M ₁₁ Or M ₆ And M ₁₂ Mutually acting as input pipes.

Preferably, said M ₁₄ And M ₁₅ Is a voltage-controlled current source, M ₁₆ -M ₁₉ Is a PMOS transistor, the M ₂₀ -M ₂₁ Is a current mirror structure; wherein the M ₁₆ -M ₁₉ For inputting a voltage; the V is _CMFB For outputting a voltage; the V is _OUTN And V _OUTP By M ₁₃ And M ₁₇ Post-conversion to current at M ₂₀ Superposition, V _CM By M ₁₇ 、M ₁₈ Post-conversion to current; the M is ₁₃ 、M ₁₉ Is passed through M ₂₀ 、M ₂₁ Current mirror copy to M ₂₁ In (3), with V _CM The current of (2) is subtracted from the output current, and the current passes through M ₂₁ Self impedance conversion to V _CMFB And input to M ₁₃ The method comprises the steps of carrying out a first treatment on the surface of the The principle of voltage and current interconversion is as follows:

wherein K is a constant, I _D Is leakage current, V _GS Is gate-source voltage, V _TH Is the transistor threshold voltage.

The beneficial effects are that:

1. the invention replaces the single PMOS transistor current source with a flipped voltage follower current source, so that the input tube (M ₅ 、M ₆ ) The dynamic current of the voltage regulator is controlled by the static current, and the dynamic current is increased;

2. the inverting voltage follower current source of the invention couples a PMOS transistor (M ₅ 、M ₆ ) The equivalent transconductance of the circuit is doubled, and the circuit gain is improved;

3. the invention uses a current multiplexing structure to divide NMOS tube and PMOS tube (M ₅ 、M ₆ 、M ₁₁ 、M ₁₂ ) And meanwhile, the circuit is used as an input tube, so that the equivalent transconductance of the whole circuit is doubled.

Drawings

FIG. 1 is a schematic diagram of an overall circuit of a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram of a conventional follower in accordance with a preferred embodiment of the present invention;

FIG. 3 is a schematic diagram of a flip-flop voltage follower in accordance with a preferred embodiment of the present invention.

Detailed Description

The following examples of the present invention are described in detail, and are given by way of illustration of the present invention, but the scope of the present invention is not limited to the following examples.

The invention designs a cascode operational amplifier based on a turnover voltage following current source, which comprises the following steps, as shown in fig. 1, and specifically comprises the following steps: a flip voltage follower current source structure, a sleeve type common source and common gate structure, a current multiplexing structure and a common mode feedback structure; the flipped voltage follower current source structure includes M ₁ 、M ₂ 、M ₃ And M ₄ The method comprises the steps of carrying out a first treatment on the surface of the The telescopic type common-source common-gate structure comprises M ₅ 、M ₆ 、M ₇ 、M ₈ 、M ₉ 、M ₁₀ 、M ₁₁ 、M ₁₂ 、M ₁₃ 、V _OUTN And V _OUTP The method comprises the steps of carrying out a first treatment on the surface of the The current multiplexing structure comprises M ₅ 、M ₆ 、M ₁₁ And M ₁₂ The method comprises the steps of carrying out a first treatment on the surface of the The common mode feedback structure is M ₁₄ 、M ₁₅ 、M ₁₆ 、M ₁₇ 、M ₁₈ 、M ₁₉ 、M ₂₀ 、M ₂₁ And V _CMFB ；M ₁ And M is as follows ₃ 、M ₅ 、M ₇ 、M ₉ 、M ₁₁ 、M ₁₃ Connecting; m is M ₂ And M is as follows ₄ 、M ₆ 、M ₈ 、M ₁₀ 、M ₁₂ 、M ₁₃ Connecting; m is M ₁₃ Grounding; the M is ₁ And M is as follows ₂ Are all connected to a power supply V _DD ；M ₇ And M is as follows ₈ Connected with bias voltage V _BP1 ；M ₉ And M is as follows ₁₀ Connected with bias voltage V _BN ；M ₁₃ Connected with bias voltage V _CMFB . The bias voltage of the circuit is V _BP1 、V _BP2 、V _BN 、V _CM And V _CMFB (i.e., the transistor supply voltage, four except for the bias voltage, which are different, the rest are the same); bias current I _BIAS 。

Specifically, an input signal is input to the M of the operational amplifier ₅ 、M ₆ 、M ₁₁ 、M ₁₂ (i.e. V _IN 、V _IP ) At the time due to M ₃ And M ₄ Gate-source voltage and M ₅ And M ₆ The gate-source voltages are the same, so M ₃ -M ₆ The resulting transconductance and bias current (I _BIAS ) The same applies; m is M ₃ -M ₆ Current at M ₅ And M ₆ The transconductance of the operational amplifier is twice that of the traditional sleeve-type cascode transconductance by superposition.

Preferably, as shown in fig. 2 and 3, the flipped voltage follower current source structure comprises: m is M ₁ -M ₄ Is an NMOS tube; wherein M is ₃ -M ₄ For inputting a voltage; m of flip-flop voltage follower structure ₁ Or M ₂ The current being fixed by respective bias currents, the bias currents first passing through M ₁ Or M ₂ Then output M ₁ Or M ₂ Voltage, M generated compared with conventional operational amplifier ₁ Or M ₂ The current is not affected by the bias current, and a larger current can be output.

Specifically, due to the flip-flop structure, the dynamic current of the operational amplifier is not limited by the static (bias) current (the generated current is greatly influenced by the bias (static) current in the conventional P/NMOS input structure, and the static tube M ₁ Its voltage V _GS Will change with the change of the output current, M is changed due to the change of the bias current position by using the reverse voltage follower structure ₁ The current of the tube is fixed by the bias current, so its V _GS The current at the output end is not limited by the influence of bias current, and can output larger current), thereby improving dynamic current.

Preferably, the telescopic cascode structure comprises: m is M ₅ -M ₈ Is a PMOS tube; wherein M is ₅ And M ₆ For inputting voltage, M ₇ -M ₈ For a load; m is M ₉ -M ₁₂ Is an NMOS tube; wherein M is ₁₁ And M ₁₂ For inputting voltage, M ₉ -M ₁₀ For a load; m is M ₁₃ Providing feedback function for voltage-controlled current source, and outputting common mode level protectionHolding constant; v (V) _OUTN And V _OUTP For outputting a voltage.

Preferably, the current multiplexing structure comprises: m is M ₅ And M ₆ Is a PMOS tube; wherein M is ₅ And M ₆ For inputting a voltage; m is M ₁₁ And M ₁₂ Is an NMOS tube; wherein M is ₁₁ And M ₁₂ For inputting a voltage. M of input signal to the operational amplifier ₅ 、M ₆ 、M ₁₁ 、M ₁₂ When the M is ₅ And M ₁₁ Or M ₆ And M ₁₂ Mutually acting as input pipes.

Specifically, when an input signal is input to V of the operational amplifier _IN 、V _IP (i.e. circuit M ₅ 、M ₆ 、M ₁₁ 、M ₁₂ ) At the time of (M) ₅ And M ₁₁ Or M ₆ And M ₁₂ And the equivalent transconductance of the sleeve type cascode operational amplifier structure is doubled compared with that of the traditional sleeve type cascode operational amplifier structure by mutually serving as an input tube. Therefore, the transconductance of the operational amplifier is four times that of the traditional sleeve type cascoded operational amplifier. From formula A _v ＝g _m, ×R _out It is known that the gain is also four times that of the conventional telescopic cascode operational amplifier, since the output impedance is similar to that of the conventional telescopic operational amplifier.

Preferably, since the present operational amplifier is a dual-input, dual-output operational amplifier, the operational amplifier also needs to have a common-mode feedback structure in order to keep the output common-mode voltage stable. The common mode feedback structure includes: m is M ₁₄ And M ₁₅ Is a voltage-controlled current source M ₁₆ -M ₁₉ Is a PMOS transistor, M ₂₀ -M ₂₁ Is a current mirror structure; wherein M is ₁₆ -M ₁₉ For inputting a voltage; v (V) _CMFB For outputting a voltage; v (V) _OUTN And V _OUTP By M ₁₃ And M ₁₇ Post-conversion to current at M ₂₀ Superposition, V _CM By M ₁₇ 、M ₁₈ Post-conversion to current; m is M ₁₃ 、M ₁₉ Is passed through M ₂₀ 、M ₂₁ Current mirror copy to M ₂₁ In (3), with V _CM The current of (2) is subtracted from the output current, and the current passes through M ₂₁ Self impedance conversion to V _CMFB And input to M ₁₃ The method comprises the steps of carrying out a first treatment on the surface of the The principle of voltage and current interconversion is as follows:

wherein K is a constant, I _D Is leakage current, V _GS Is gate-source voltage, V _TH Is the transistor threshold voltage.

Specifically, when V _OUTN And V _OUTP When the value of (2) is large, V _CMFB Reduce and thus M ₁₃ Is reduced so that V _OUTN And V _OUTP Constant. When V is _OUTN And V _OUTP And vice versa when the value of (c) is smaller.

The foregoing describes in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be made in accordance with the concepts of the invention without requiring creative effort by one of ordinary skill in the art. Therefore, all technical solutions which can be obtained by logic analysis, reasoning or limited experiments based on the prior art by a person skilled in the art according to the inventive concept shall be within the scope of protection defined by the claims.

Claims (5)

1. A cascode operational amplifier based on a flipped voltage follower current source, comprising:

a flip voltage follower current source structure, a sleeve type common source and common gate structure, a current multiplexing structure and a common mode feedback structure;

the flipped voltage follower current source structure includes M ₁ 、M ₂ 、M ₃ And M ₄ The method comprises the steps of carrying out a first treatment on the surface of the The sleeve type common-source common-gate structure comprises M ₅ 、M ₆ 、M ₇ 、M ₈ 、M ₉ 、M ₁₀ 、M ₁₁ 、M ₁₂ 、M ₁₃ 、V _OUTN And V _OUTP The method comprises the steps of carrying out a first treatment on the surface of the The current multiplexing structure comprises M ₅ 、M ₆ 、M ₁₁ And M ₁₂ The method comprises the steps of carrying out a first treatment on the surface of the The common modeThe feedback structure is M ₁₄ 、M ₁₅ 、M ₁₆ 、M ₁₇ 、M ₁₈ 、M ₁₉ 、M ₂₀ 、M ₂₁ And V _CMFB ；

The M is ₁ And M is as follows ₃ 、M ₅ 、M ₇ 、M ₉ 、M ₁₁ 、M ₁₃ Connecting; the M is ₂ And M is as follows ₄ 、M ₆ 、M ₈ 、M ₁₀ 、M ₁₂ 、M ₁₃ Connecting; the M is ₁₃ Grounding; the M is ₁ And M is as follows ₂ Are all connected to a power supply V _DD The method comprises the steps of carrying out a first treatment on the surface of the The M is ₇ And M is as follows ₈ Connected with bias voltage V _BP1 The method comprises the steps of carrying out a first treatment on the surface of the The M is ₉ And M is as follows ₁₀ Connected with bias voltage V _BN The method comprises the steps of carrying out a first treatment on the surface of the The M is ₁₃ Connected with bias voltage V _CMFB 。

2. A cascode operational amplifier based on a flipped voltage follower current source as recited in claim 1 wherein:

the M is ₁ -M ₄ Is an NMOS tube; wherein the M ₃ -M ₄ For inputting a voltage;

m of the flip-flop structure ₁ Or M ₂ The current being fixed by respective bias currents, the bias currents first passing through M ₁ Or M ₂ Then output M ₁ Or M ₂ A voltage.

3. A cascode operational amplifier based on a flipped voltage follower current source as recited in claim 1 wherein:

the M is ₅ -M ₈ Is a PMOS tube; wherein the M ₅ And M ₆ For inputting voltage, M ₇ -M ₈ For a load;

the M is ₉ -M ₁₂ Is an NMOS tube; wherein the M ₁₁ And M ₁₂ For inputting voltage, M ₉ -M ₁₀ For a load;

the M is ₁₃ Providing feedback function for voltage-controlled current source, and outputting common mode electricityThe level is kept constant;

the V is _OUTN And V _OUTP For outputting a voltage.

4. A cascode operational amplifier based on a flipped voltage follower current source as recited in claim 1 wherein:

the M is ₅ And M ₆ Is a PMOS tube; wherein the M ₅ And M ₆ For inputting a voltage;

the M is ₁₁ And M ₁₂ Is an NMOS tube; wherein the M ₁₁ And M ₁₂ For inputting a voltage;

m of input signal to the operational amplifier ₅ 、M ₆ 、M ₁₁ 、M ₁₂ When the M is ₅ And M ₁₁ Or M ₆ And M ₁₂ Mutually acting as input pipes.

5. A cascode operational amplifier based on a flipped voltage follower current source as recited in claim 1 wherein:

the M is ₁₄ And M ₁₅ Is a voltage-controlled current source, M ₁₆ -M ₁₉ Is a PMOS transistor, the M ₂₀ -M ₂₁ Is a current mirror structure; wherein the M ₁₆ -M ₁₉ For inputting a voltage; the V is _CMFB For outputting a voltage;

the V is _OUTN And V _OUTP By M ₁₃ And M ₁₇ Post-conversion to current at M ₂₀ Superposition, V _CM By M ₁₇ 、M ₁₈ Post-conversion to current;

the M is ₁₃ 、M ₁₉ Is passed through M ₂₀ 、M ₂₁ Current mirror copy to M ₂₁ In (3), with V _CM The current of (2) is subtracted from the output current, and the current passes through M ₂₁ Self impedance conversion to V _CMFB And input to M ₁₃ ；

The principle of voltage and current interconversion is as follows:

wherein K is a constant, I _D Is leakage current, V _GS Is gate-source voltage, V _TH Is the transistor threshold voltage.