A slew rate enhancement amplifier

Abstract

The application discloses a slew rate enhancement amplifier, which comprises a bias stage, an input stage, an amplification stage and a driving stage connected in sequence, and a slew rate enhancement circuit for detecting the voltage variation of the input stage of the amplifier and converting the voltage variation into a current, wherein the converted current is fed back to compensate the bias tail current of the input stage of the amplifier. The slew rate enhancement circuit comprises a current source I1, junction field effect tubes Q3 and Q4, and triodes Q5, Q6, Q7, Q18, Q9, Q10, Q11, Q12, Q13, Q14, Q15 and Q16. The bias tail current source is proportional to the size of the current source I1. The application adds the slew rate enhancement circuit in the amplifier, which converts the detected voltage variation of the input stage of the amplifier into a current, and the current is fed back to compensate the bias tail current of the input stage of the amplifier. Meanwhile, the circuit has a rapid recovery function and can rapidly respond to the voltage of the next pulse, and the application can effectively improve the voltage slew rate of the amplifier without affecting the frequency stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of amplifier, in particular to a swing enhancement amplifier for improving the voltage swing of the amplifier without affecting the frequency stability. BACKGROUND

[0002] The voltage swing of the conventional amplifier is proportional to the bias tail current source of the input stage of the amplifier. The amplifier with CMOS device as the input stage is not suitable for the low noise field because of the high noise voltage. The amplifier with BIPOLAR device as the input stage is not suitable for the high impedance field because of the low input impedance of the BIPOLAR device, and the input linear range is small under the same bias current condition because of the high transconductance of the BIPOLAR device. The amplifier with JFET as the input stage has the characteristics of low noise voltage and high input impedance, and the transconductance is smaller than that of the BIPOLAR device, so the bias tail current source can be set to be large to obtain a high swing. SUMMARY

[0003] The purpose of the present application is to provide a swing enhancement amplifier, which can effectively improve the voltage swing of the amplifier without affecting the frequency stability by adding a swing enhancement circuit in the amplifier.

[0004] The technical scheme of the present application is as follows:

[0005] A swing enhancement amplifier, comprising a bias stage, an input stage, an amplification stage and a driving stage connected in sequence, and further comprising a swing enhancement circuit for detecting the voltage variation of the input stage of the amplifier and converting the voltage variation into a current, and the converted current is fed back to compensate the bias tail current of the input stage of the amplifier.

[0006] Preferably, the swing enhancement circuit comprises a current source I1, JFETs Q3 and Q4, and triodes Q11, Q12, Q13, Q14, Q15 and Q16; wherein:

[0007] The gates of the JFETs Q3 and Q4 are input with voltages INA+ and INA- respectively; one end of each of the JFETs Q3 and Q4 is connected to the power supply VCC through the triodes Q11 and Q12 respectively, and the other end of each of the JFETs Q3 and Q4 is connected to the power supply VEE through the bias tail current source; the bias tail current source is proportional to the size of the current source I1;

[0008] The common junction point P of the JFET Q3 and the triode Q11, and the common junction point Q of the JFET Q4 and the triode Q12 are connected to the bases of the triodes Q13 and Q14 respectively, the emitters of the triodes Q13 and Q14 are connected to the power supply VCC respectively, and the collectors of the triodes Q13 and Q14 are connected together; the triodes Q15 and Q16 are connected between the power supply VCC and the bases of the triodes Q13 and Q14 respectively, and the triodes Q15 and Q16 are short-circuited to their own bases and collectors.

[0009] Preferably, the current source I1 and the triodes Q5, Q7 and Q8 constitute a feedback current source, the positive pole of the current source I1 is connected to the power supply VCC end, and the negative pole is connected to the power supply VEE end through the triode Q7; the base of the triode Q5 is connected to the negative pole of the current source I1, the collector is connected to the power supply VCC end through the triode Q10, and the emitter is connected to the power supply VEE end through the triode Q8; the base of the triode Q8 is connected to the base of the triode Q7, and the base and the collector of the triodes Q8 and Q10 are shorted respectively; the base of the triode Q10 is connected to the bases of the triodes Q11 and Q12 respectively.

[0010] Preferably, the bias tail current source is proportional to the size of the feedback current source I1, including the triodes Q6 and Q9, the collector of the triode Q6 is connected to the common connection point of the field effect tubes Q3 and Q4, the emitter of the triode Q6 is connected to the collector of the triode Q9, the emitter of the triode Q9 is connected to the power supply VEE end, and the bases of the triodes Q6 and Q9 are connected to the negative pole of the current source I1 and the base of the triode Q7 respectively.

[0011] Preferably, the triodes Q5, Q6, Q7, Q8 and Q9 are NPN type triodes, and the triodes Q10, Q11, Q12, Q13, Q14, Q15 and Q16 are PNP type triodes.

[0012] The advantages of the present application are:

[0013] The present application is a swing rate enhancement amplifier, which adds a swing rate enhancement circuit in the amplifier, converts the detected change of the input voltage of the amplifier into a current, and feeds back the current to compensate the bias tail current of the input stage of the amplifier; meanwhile, the circuit has a fast recovery function and can quickly respond to the next pulse voltage, so that the present application can effectively improve the voltage swing rate of the amplifier without affecting the frequency stability. BRIEF DESCRIPTION OF DRAWINGS

[0014] The present application will be further described below in combination with the drawings and embodiments:

[0015] Figure 1 It is a schematic diagram of the swing rate enhancement amplifier of the present application;

[0016] Figure 2 It is a comparison diagram of the voltage swing rate simulation waveform of the swing rate enhancement amplifier of the present application. DETAILED DESCRIPTION

[0017] As Figure 1As shown, the slew rate enhancement amplifier of the present application is a JFET input amplifier, which comprises a bias stage, an input stage, an amplification stage and a driving stage connected in sequence, and further comprises a slew rate enhancement circuit for detecting the voltage variation of the input stage of the amplifier and converting it into a current, and the converted current is fed back to compensate the bias tail current of the input stage of the amplifier. Meanwhile, the circuit has a fast recovery function and can quickly respond to the voltage of the next pulse. The present application can effectively improve the voltage slew rate of the amplifier without affecting the frequency stability.

[0018] Specifically, the JFET amplifier described in the embodiment is composed of an input stage, an amplification stage, a driving stage and a bias stage. The input stage is composed of junction field effect tubes Q1 and Q2, triodes Q6A, Q9A, Q17, Q18, Q19, Q20 and Q21, resistors R1, R2 and R3, and a current source I3. The bias stage is composed of triodes Q5A, Q7A and Q8A, and a current source I2.

[0019] The slew rate enhancement circuit comprises a current source I1, junction field effect tubes Q3 and Q4, and triodes Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15 and Q16. Wherein:

[0020] The gates of the field effect tubes Q3 and Q4 are respectively input with voltages INA+ and INA-. One end of each of the field effect tubes Q3 and Q4 is connected to the power supply VCC through the triodes Q11 and Q12, and the other end of each of the field effect tubes Q3 and Q4 is connected to the power supply VEE through a bias tail current source. The bias tail current source mirrors the size of the current source I1 in proportion.

[0021] The common junction point P of the field effect tube Q3 and the triode Q11, and the common junction point Q of the field effect tube Q4 and the triode Q12 are respectively connected to the bases of the triodes Q13 and Q14. The emitters of the triodes Q13 and Q14 are respectively connected to the power supply VCC, and the collectors are commonly connected to the bias stage of the amplifier. The triodes Q15 and Q16 are respectively connected between the power supply VCC and the bases of the triodes Q13 and Q14, and the triodes Q15 and Q16 are short-circuited to their own bases and collectors.

[0022] The current source I1 and the triodes Q5, Q7 and Q8 constitute a feedback current source. The positive electrode of the current source I1 is connected to the power supply VCC, and the negative electrode is connected to the power supply VEE through the triode Q7. The base of the triode Q5 is connected to the negative electrode of the current source I1, the collector is connected to the power supply VCC through the triode Q10, and the emitter is connected to the power supply VEE through the triode Q8. The base of the triode Q8 is connected to the base of the triode Q7, and the bases and collectors of the triodes Q8 and Q10 are respectively short-circuited. The base of the triode Q10 is respectively connected to the bases of the triodes Q11 and Q12.

[0023] The bias tail current source mirrors the size of I1 by a feedback current source, comprising triodes Q6, Q9, the collector of triode Q6 is connected to the common point of field effect tubes Q3, Q4, the emitter of triode Q6 is connected to the collector of triode Q9, the emitter of triode Q9 is connected to power supply VEE, the base of triode Q6 is connected to the negative pole of current source I1 and the base of triode Q7.

[0024] The triodes Q5, Q6, Q7, Q8, Q9 in the embodiment are NPN type triodes, and the triodes Q10, Q11, Q12, Q13, Q14, Q15, Q16 are PNP type triodes.

[0025] When the gate input voltage INA+ and INA- are equal, the voltages of P point and Q point are close to VCC voltage, and the triodes Q13-Q16 are not conductive; when the input voltages INA+ and INA- change, the change amount of voltage is conducted to P point and Q point, and the triode Q13 is conductive or the triode Q14 is conductive, depending on the relative size of INA+ and INA-.

[0026] When the gate input voltage INA+ is greater than INA-, the triode Q13 is conductive, and the current of triode Q13 is injected to the bias stage node B of the amplifier, so that the bias tail current of the junction field effect tubes Q1, Q2 of the input stage of the amplifier increases, and the voltage swing increases; the area ratio of the emitter stage of triode Q15 and triode Q13 is set, when the amplifier is close to stable through feedback, the triode Q15 is conductive, the base potential of triode Q13 is raised, the triode Q13 is cut off, and no longer injects current to the bias stage node B, so as not to affect the stability of the amplifier. Similarly, the working process when the voltage INA+ is less than INA-.

[0027] As Figure 2 shown, it is a comparison chart of voltage swing simulation waveforms of the swing enhancement amplifier, the time of rising to stability and the time of falling to stability of the swing enhancement amplifier of the present application are both shortened compared with the amplifier without swing enhancement.

[0028] The above embodiment is only for illustrating the technical concept and characteristics of the present application, and its purpose is to enable those skilled in the art to understand the content of the present application and implement it, and it cannot limit the protection scope of the present application. Any modification made according to the spirit and essence of the main technical solution of the present application should be covered in the protection scope of the present application.

Claims

1. A slew rate enhanced amplifier comprising a bias stage, an input stage, an amplification stage and a driver stage connected in sequence, characterized in that, Also include the slew rate enhancement circuit, for detecting the change of amplifier input stage voltage, and into the current, the conversion current feedback compensation amplifier input stage bias current; The slew rate enhancement circuit includes current source I1, junction field effect transistor Q3, Q4 and triode Q5, Q6, Q7, Q18, Q9, Q10, Q11, Q12, Q13, Q14, Q15, Q16; wherein: The gate of field effect transistor Q3, Q4 is input voltage INA+ and INA- respectively; one end of field effect transistor Q3, Q4 is connected to power supply VCC end through triode Q11, Q12 respectively, and the other end is connected to power supply VEE end through bias current source; the bias current source is proportional to the size of current source I1; The common point P of field effect transistor Q3 and triode Q11, and the common point Q of field effect transistor Q4 and triode Q12 are connected to the base of triode Q13, Q14 respectively, the emitter of triode Q13, Q14 is connected to power supply VCC end respectively, and the collector is connected to the bias stage of amplifier; the two ends of triode Q15, Q16 are connected to power supply VCC end and the base of triode Q13, Q14 respectively, and the base and collector of triode Q15, Q16 are shorted; The current source I1 and triode Q5, Q7 and Q8 constitute a feedback current source, the positive electrode of current source I1 is connected to power supply VCC end, and the negative electrode is connected to power supply VEE end through triode Q7; the base of triode Q5 is connected to the negative electrode of current source I1, the collector is connected to power supply VCC end through triode Q10, and the emitter is connected to power supply VEE end through triode Q8; the base of triode Q8 is connected to the base of triode Q7, and the base and collector of triode Q8, Q10 are shorted respectively; the base of triode Q10 is connected to the base of triode Q11, Q12 respectively.

2. A slew rate enhancement amplifier according to claim 1, characterised in that, The bias current source is proportional to the size of I1 through feedback current source, including triode Q6, Q9, the collector of triode Q6 is connected to the common point of field effect transistor Q3, Q4, the emitter of triode Q6 is connected to the collector of triode Q9, the emitter of triode Q9 is connected to power supply VEE end, and the base of triode Q6, Q9 is connected to the negative electrode of current source I1 and the base of triode Q7 respectively.

3. A slew rate enhancement amplifier according to claim 2, characterised in that, The triode Q5, Q6, Q7, Q8, Q9 is NPN type triode, and the triode Q10, Q11, Q12, Q13, Q14, Q15, Q16 is PNP type triode.

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