CN115940855A - High common mode rejection trans-impedance amplifier and optical coupler chip - Google Patents
High common mode rejection trans-impedance amplifier and optical coupler chip Download PDFInfo
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Abstract
The invention relates to the technical field of transimpedance amplifiers, and discloses a high common-mode rejection transimpedance amplifier and an optical coupler chip, wherein the high common-mode rejection transimpedance amplifier comprises a first common emitter amplification unit, a feedback unit and a second common emitter amplification unit; the first common emitter amplifying units are symmetrically arranged, amplify input current signals and output two paths of first voltage signals; the feedback unit comprises two symmetrically arranged feedback branches and feeds the two first voltage signals back to the two first differential input ends; the second common emitter amplifying units are symmetrically arranged and amplify the two paths of first voltage signals, so that the overall gain of the transimpedance amplifier is increased; in addition, the first common emitter amplifying unit and the second common emitter amplifying unit are both of a fully differential structure and are symmetrically arranged, so that the common mode rejection ratio of the invention can be improved.
Description
Technical Field
The invention relates to the technical field of transimpedance amplifiers, in particular to a high common-mode rejection transimpedance amplifier and an optical coupler chip.
Background
A Transimpedance Amplifier (TIA) is an extremely important component in an optocoupler chip, and is usually used as a preamplifier to amplify a weak current and convert the weak current into a voltage signal for processing by a subsequent circuit.
A transimpedance amplifier used in an existing optocoupler chip is a Common Source (CS) transimpedance amplifier, and a circuit thereof is shown in fig. 1. In fig. 1, a MOS (Metal-Oxide-semiconductor field-Effect Transistor, MOSFET) Transistor M1 serves as an input stage, a MOS Transistor M2 serves as a primary source follower for driving a MOS Transistor M3, and the MOS Transistor M3 serves as a secondary source follower; in addition, MOS tube M1, MOS tube M2 and resistor Rf form input end parallel negative feedback loop, equivalent input impedance R i ≈R f /(1+g m1 *R 1 ) Wherein g is m1 Is the transconductance of the MOS transistor M1. In practical use, after a current signal is input to the input stage, the current signal flows into the constant current source through the feedback resistor Rf, and an input voltage drop is formed on the feedback resistor Rf; the input voltage is amplified by the MOS tube M1, and the drain-source current of the input voltage is adjusted by the transconductance action of the MOS tube M2, so that the current value of the constant current source is kept constant.
In the optical coupler chip, current is generally generated by a photosensitive diode, the current value is very small, usually in microampere level, so that a trans-impedance amplifier is required to have larger gain, and a small current signal is converted into a larger voltage signal. However, the transimpedance amplifier shown in fig. 1 is a first-stage amplification circuit, and has a low gain, and cannot meet the use requirements of the optocoupler chip. In addition, the common-source amplifier with the gate input is used as an input stage, because of the miller capacitance effect, an equivalent parasitic capacitance between the gate and the drain which is multiplied exists at the input terminal, the parasitic capacitance limits the bandwidth of the trans-impedance amplifier, and the common-mode rejection is low.
Disclosure of Invention
In view of the defects of the background art, the invention provides a high common-mode rejection trans-impedance amplifier, and aims to solve the technical problem that a common-source trans-impedance amplifier used in the existing optical coupling chip has low common-mode rejection and cannot meet the use requirements of certain optical coupling chips.
In order to solve the above technical problems, in a first aspect, the present invention provides the following technical solutions: a high common mode rejection trans-impedance amplifier comprises a first common emitter amplification unit, a feedback unit and a second common emitter amplification unit; the first common emitter amplifying units are symmetrically arranged, comprise two first differential input ends, are configured to amplify input current signals and output two paths of first voltage signals; the feedback unit comprises two symmetrically arranged feedback branches, and the two feedback branches are electrically connected with the first common emitter amplifying unit and used for feeding back two first voltage signals to two first differential input ends; the second common emitter amplifying units are symmetrically arranged and comprise two second differential input ends, two paths of first voltage signals are input into the two second differential input ends, and the second common emitter amplifying units are used for amplifying the two paths of first voltage signals and outputting two paths of second voltage signals.
In one embodiment of the first aspect, the first common emitter amplifying unit includes a first resistor R1, a second resistor R2, a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a first current source I1, a second current source I2, and a third current source I3; one end of the first resistor R1 and one end of the second resistor R2 are configured to input a working power supply; the other end of the first resistor R1 is respectively and electrically connected with a collector electrode of a first triode Q1 and a base electrode of a third triode Q3, and the other end of the second resistor R2 is respectively and electrically connected with a collector electrode of a second triode Q2 and a base electrode of a fourth triode Q4; the emitting electrode of the first triode Q1 and the emitting electrode of the second triode Q2 are grounded through the first current source I1 respectively; the collector electrode of the third triode Q3 and the collector electrode of the fourth triode Q4 are configured to input a working power supply; the emitter of the third triode Q3 is grounded through a second current source I2, and the emitter of the fourth triode Q4 is grounded through a third current source I3; and the emitting electrode of the third triode Q3 and the emitting electrode of the fourth triode Q3 output two paths of first voltage signals.
In one embodiment of the first aspect, the present invention further comprises a first photodiode D1 and a second photodiode D2; the base electrode of the first triode Q1 is electrically connected with the anode of the first photosensitive diode D1, and the base electrode of the second triode Q2 is electrically connected with the anode of the second photosensitive diode D2; the cathode of the first photodiode D1 and the cathode of the second photodiode D2 are configured to input a working power.
In one embodiment of the first aspect, the resistance of the first resistor R1 is the same as the resistance of the second resistor R2, the width-to-length ratio of the first transistor Q1 is the same as the width-to-length ratio of the second transistor Q2, and the width-to-length ratio of the third transistor Q3 is the same as the width-to-length ratio of the fourth transistor Q4.
In a certain embodiment of the first aspect, the feedback branch comprises a feedback capacitance and a feedback resistance;
one end of a feedback capacitor in one feedback branch circuit is electrically connected with one end of a feedback resistor and is configured to input one path of first voltage signals; the other end of the feedback capacitor and the other end of the feedback resistor in the feedback branch are respectively and electrically connected with a first differential input end;
one end of a feedback capacitor in the other feedback branch circuit is electrically connected with one end of a feedback resistor and is configured to input the other first voltage signal; and the other end of the feedback capacitor in the other feedback branch circuit and the other end of the feedback resistor are respectively and electrically connected with the other first differential input end.
In a certain implementation manner of the first aspect, the capacitance values of the feedback capacitors in the two feedback branches are the same, and the resistance values of the feedback resistors in the two feedback branches are the same.
In one embodiment of the first aspect, the second common emitter amplifying unit includes a fifth resistor R5, a sixth resistor R6, a fifth transistor Q5, a sixth transistor Q6, and a fourth current source I4; one end of the fifth resistor R5 and one end of the sixth resistor R6 are configured to input a working power supply; the other end of the fifth resistor R5 is electrically connected with the collector of a fifth triode Q5, and the other end of the sixth resistor R6 is electrically connected with the collector of a sixth triode Q6; the emitter of the fifth triode Q5 and the emitter of the sixth triode Q6 are grounded through the fourth current source I4; the base electrode of the fifth triode Q5 is electrically connected with the emitting electrode of the third triode Q3, and the base electrode of the sixth triode Q6 is electrically connected with the emitting electrode of the fourth triode Q4.
In one embodiment of the first aspect, the resistance of the fifth resistor is the same as the resistance of the sixth resistor, and the width-to-length ratio of the fifth transistor Q5 is the same as the width-to-length ratio of the sixth transistor Q6.
In a second aspect, the invention further provides an optical coupler chip, which includes the high common mode rejection trans-impedance amplifier.
Compared with the prior art, the invention has the beneficial effects that: firstly, an input current signal is converted into a voltage signal by arranging a first common emitter amplification unit, and then the voltage signal is amplified by a second common emitter amplification unit, so that the overall gain of the trans-impedance amplifier is increased; secondly, the first common emitter amplification unit and the second common emitter amplification unit are symmetrically arranged respectively and adopt differential input structures, so that high common mode rejection and low noise of the trans-impedance amplifier are realized; finally, a differential amplifier is needed to further amplify the two paths of second voltage signals in practical application, and the second common emitter amplifying unit with the differential input structure is arranged to be conveniently cascaded with the differential amplifier, so that a single-end-double-end conversion circuit does not need to be additionally arranged in the circuit, and monolithic integration is easy to realize.
Drawings
Fig. 1 is a circuit diagram of a conventional common source transimpedance amplifier circuit;
FIG. 2 is a schematic structural view of the present invention;
FIG. 3 is a schematic diagram of the structure of FIG. 2 coupled to two photodiodes;
FIG. 4 is a circuit diagram of an embodiment of the present invention;
fig. 5 is a circuit diagram showing the connection between the circuit shown in fig. 4 and two photodiodes.
In the figure: 1. a first common emitter amplifying unit, 2, a feedback unit, 3, a second common emitter amplifying unit, 20, a first feedback branch, 21, a second feedback branch.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams each illustrating the basic structure of the present invention only in a schematic manner, and thus show only the constitution related to the present invention.
As shown in fig. 2, a high common mode rejection transimpedance amplifier includes a first common emitter amplifying unit 1, a feedback unit 2 and a second common emitter amplifying unit 3;
the first common emitter amplifying units 1 are symmetrically arranged and comprise two first differential input ends and two first differential output ends, wherein the two first differential input ends are respectively a first differential input end IN10 and a first differential input end IN11, and the two first differential output ends are respectively a first differential output end OUT10 and a first differential output end OUT11; the first common emitter amplification unit 1 is configured to amplify an input current signal and output two first voltage signals; wherein the differential current is input to two first differential input terminals, the current i1 input to the first differential input terminal IN10 is sink current, and the current i2 input to the second differential input terminal IN11 is source current; two paths of first voltage signals are output by two first differential output ends;
the feedback unit 2 comprises two symmetrically arranged feedback branches 20, and the two feedback branches 20 are electrically connected with the first common emitter amplification unit 1 and used for feeding back two first voltage signals to two first differential input ends;
the second common emitter amplifying units 3 are symmetrically arranged and comprise two second differential input ends and two second output ends, wherein the two second differential input ends are respectively a second differential input end IN20 and a second differential input end IN21, and the two second output ends are respectively a second output end OUT20 and a second output end OUT21; the two second differential input ends respectively input one path of first voltage signals, and the second common emitter amplifying unit 3 is used for amplifying the two paths of first voltage signals and outputting two paths of second voltage signals; wherein the two paths of second voltage signals are output by the two second output ends.
For the invention, the first common emitter amplifying unit 1 is arranged to convert the current signal into the first voltage signal, and the second common emitter amplifying unit 3 is used to amplify the first voltage signal, so that the overall gain of the trans-impedance amplifier is increased; the first common emitter amplifying unit 1 and the second common emitter amplifying unit 3 both adopt a differential input structure, so that low noise of the transimpedance amplifier is realized; finally, a differential amplifier is needed to further amplify the two paths of second voltage signals in practical application, and the second common emitter amplifying unit 3 with the differential input structure is arranged to be conveniently cascaded with the differential amplifier, so that a single-end-double-end conversion circuit does not need to be additionally arranged in the circuit, and monolithic integration is easy to realize.
For the circuit shown IN fig. 3, the first differential input IN10 is electrically connected to the anode of the first photodiode D1, and the second differential input IN11 is electrically connected to the anode of the second photodiode D2. IN practical use, only one of the first photodiode D1 and the second photodiode D2 is illuminated, IN this embodiment, the first photodiode D1 is illuminated, and the first photodiode D1 generates a photocurrent signal inputted to the first differential input terminal IN 10.
Specifically, referring to fig. 4, in the circuit shown in fig. 4, the first common emitter amplifying unit 1 includes a first resistor R1, a second resistor R2, a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a first current source I1, a second current source I2, and a third current source I3;
one end of the first resistor R1 and one end of the second resistor R2 are configured to input the working power supply; the other end of the first resistor R1 is respectively and electrically connected with the collector of the first triode Q1 and the base of the third triode Q3, and the other end of the second resistor R2 is respectively and electrically connected with the collector of the second triode Q2 and the base of the fourth triode Q4; an emitting electrode of the first triode Q1 and an emitting electrode of the second triode Q2 are grounded through a first current source I1 respectively; the collector of the third triode Q3 and the collector of the fourth triode Q4 are configured to the input working power supply; the emitter of the third triode Q3 is grounded through a second current source I2, and the emitter of the fourth triode Q4 is grounded through a third current source I3; the emitting electrode of the third triode Q3 and the emitting electrode of the fourth triode Q3 output two paths of first voltage signals.
For the first common emitter amplifying unit 1 in fig. 4, the base of the first triode Q1 and the base of the second triode Q2 are two first differential input terminals, and the current i1 and the current i2 are respectively input to the base of the first triode Q1 and the base of the second triode Q2 as differential currents. The emitter of the third transistor Q3 is a first differential output terminal OUT10, and the emitter of the fourth transistor Q4 is a first differential output terminal OUT11.
In addition, compared with the common-source-stage amplification circuit shown in fig. 1, the input resistance of the transimpedance amplifier can be reduced by replacing the MOS transistor of the input stage with a triode, because the triode is a current driving device and has very low input impedance. In addition, under the same current condition, the transconductance of the triode is larger than that of the MOS tube, so that the thermal noise of the device of the triode is low, and the current carrier of the triode moves in the body and is a non-surface device, so that the flicker noise of the triode is very small.
For the first common emitter amplifying unit 1 in fig. 4, in order to reduce the common mode noise of the present invention, the first common emitter amplifying unit 1 of the present invention is a fully differential symmetrical structure, that is, the resistance value of the first resistor R1 is the same as the resistance value of the second resistor R2, the width-to-length ratio of the first triode Q1 is the same as the width-to-length ratio of the second triode Q2, and the width-to-length ratio of the third triode Q3 is the same as the width-to-length ratio of the fourth triode Q4.
For the first common emitter amplifying unit 1 in fig. 4, the third transistor Q3 and the fourth transistor Q4 are respectively used as emitter followers, and function as voltage buffers; in addition, the load of the third triode Q3 is a fifth triode Q5, the load of the fourth triode Q4 is a sixth triode Q6, the fifth triode Q5 and the sixth triode Q6 are output buffer stages with large parasitic capacitance, and the emitter follower has large current driving capability, so that the time delay of high-speed signals on a transmission line with large parasitic capacitance can be reduced by arranging the third triode Q3 and the fourth triode Q4; in addition, from the aspect of frequency domain, when the second common emitter amplifying unit 3 is driven by the emitter follower, a conjugate pole is generated, and the bandwidth can be properly expanded.
In fig. 4, the two feedback branches are a first feedback branch 20 and a second feedback branch 21, respectively, the circuits of the two feedback branches are the same, and taking the first feedback branch 20 as an example, the first feedback branch 20 includes a feedback capacitor C2 and a feedback resistor R4; an emitting electrode of the third triode Q3 is respectively and electrically connected with one end of the feedback capacitor C2, one end of the feedback resistor R4 and the positive electrode of the second current source I2; the other end of the feedback capacitor C2 and the other end of the feedback resistor R4 are respectively electrically connected with a first differential input end.
In order to reduce the common mode noise of the present invention, the feedback unit 2 of the present invention is a fully differential symmetrical structure, that is, the capacitance values of the feedback capacitors in the two feedback branches are the same, and the resistance values of the feedback resistors in the two feedback branches are the same.
In fig. 4, the second common emitter amplifying unit 3 includes a fifth resistor R5, a sixth resistor R6, a fifth transistor Q5, a sixth transistor Q6, and a fourth current source I4; one end of a fifth resistor R5 and one end of a sixth resistor R6 are configured to input the working power supply; the other end of the fifth resistor R5 is electrically connected with the collector of the fifth triode Q5, and the other end of the sixth resistor R6 is electrically connected with the collector of the sixth triode Q6; an emitting electrode of the fifth triode Q5 and an emitting electrode of the sixth triode Q6 are grounded through a fourth current source I4; the base electrode of the fifth triode Q5 is electrically connected with the emitting electrode of the third triode Q3, and the base electrode of the sixth triode Q6 is electrically connected with the emitting electrode of the fourth triode Q4.
The base of the fifth triode Q5 and the base of the sixth triode Q6 are two second input terminals, and taking fig. 4 as an example, the base of the fifth triode Q5 is electrically connected with the emitter of the third triode Q3, and the base of the sixth triode Q6 is electrically connected with the emitter of the fourth triode Q4. In one embodiment, the base of the fifth transistor Q5 may be electrically connected to the emitter of the fourth transistor Q4, and the base of the sixth transistor Q6 may be electrically connected to the emitter of the fourth transistor Q4. In addition, the collector of the fifth triode Q5 and the collector of the sixth triode Q6 are two second output terminals.
For the second common emitter amplifying unit 3 shown in fig. 4, in order to reduce the common mode noise of the present invention, the second common emitter amplifying unit 3 of the present invention is a fully differential symmetrical structure, that is, the resistance of the fifth resistor R5 is the same as the resistance of the sixth resistor R6, and the width-to-length ratio of the fifth triode Q5 is the same as the width-to-length ratio of the sixth triode Q6.
In a high-speed transimpedance amplifier, the influence of common mode noise on a circuit is large. For the circuit of the present invention shown in fig. 4, the first common emitter amplifying unit 1, the amplifying unit of the feedback unit 2 and the second common emitter amplifying unit 3 are all in a differential structure, and the whole circuit is in a fully differential structure, so that the common mode noise can be effectively reduced. In addition, the resistance values of the first resistor R1 and the second resistor R2 are the same, the width-to-length ratio of the first triode Q1 and the second triode Q2 is the same, the resistance value of the feedback resistor R3 is the same as the resistance value of the feedback resistor R4, the resistance value of the feedback capacitor C1 is the same as the capacitance value of the feedback capacitor C2, the width-to-length ratio of the third triode Q3 and the fourth triode Q4 is the same, the resistance value of the fifth resistor R5 is the same as the resistance value of the sixth resistor R6, and the width-to-length ratio of the fifth triode Q5 is the same as the width-to-length ratio of the sixth triode Q6, so that the whole circuit is symmetrically arranged, the even harmonic distortion can be ignored, and the signal-to-noise ratio is better.
The bandwidth of the present invention will now be explained: the input resistance of the first cascode stage amplifying unit 1 is extremely small, so that the bandwidth is greatly expanded, and the first cascode stage amplifying unit 1 can provide a virtual ground input impedance, so that the isolation effect on the parasitic capacitance is better. Therefore, the transimpedance amplifier using the adjustable first common emitter amplifying unit as the input stage can reduce the influence of the parasitic capacitance of the photosensitive diode on the bandwidth of the preamplifier more than the transimpedance amplifiers with other structures. In addition, the capacitor C1 and the capacitor C2 are used for isolating noise and improving common mode rejection.
The operation of the circuit shown in fig. 4 is as follows:
when the base current flowing into the first triode Q1 is the same as the base current of the second triode, namely the magnitude and direction of the current i1 and the current i2 are the same, the base voltages of the first triode Q1 and the second triode Q2 are designed to be the same direct current voltage, and the collectors of the fifth triode Q5 and the sixth triode Q6 also output the same voltage;
when the current i1 and the current i2 respectively flow into the base electrode of the first triode Q1 and the base electrode of the second triode Q2 as differential currents, the pouring current flowing into the base electrode of the first triode Q1 is the current i1, and the source current flowing into the base electrode of the second triode Q2 is the current i2; the current is poured to form a voltage drop on the feedback resistor R3, so that the base voltage of the first triode Q1 is higher than that of the second triode Q2, the current flowing through the branch of the first triode Q1 is more than that of the branch of the second triode Q2, and the voltage drop on the first resistor R1 is greater than that of the second resistor R2, so that the collector voltage of the first triode Q1 is lower than that of the collector voltage of the second triode Q2, the voltage difference between the base and the emitter of the third triode Q3 and the fourth triode Q4 is reduced, the base voltage of the fifth triode Q5 is greater than that of the sixth triode Q6, the current flowing through the branch of the fifth triode Q5 is increased, the current flowing through the branch of the sixth triode Q6 is reduced, the voltage drop on the fifth resistor R5 is greater than that of the sixth resistor R6, and finally the collector voltage of the fifth triode Q5 is reduced and the collector voltage of the sixth triode Q6 is increased; similarly, the current i2 finally decreases the collector voltage of the fifth triode Q5 and increases the collector voltage of the sixth triode Q6, and a differential structure is used to achieve higher gain.
In addition, a negative feedback path is formed by the feedback resistor R3 and the feedback resistor R4, and provides bias voltage for the base electrode of the first triode Q1 and the base electrode of the second triode Q2; if the base voltage of first triode Q1 increases, can make first triode Q1's collector current increase, then first resistance R1's pressure drop increases, make fourth triode Q4's base voltage reduce, and then make fourth triode Q4's emitter voltage reduce, make the voltage on the feedback resistance R3 increase slightly but be less than the range that fourth triode Q4's emitter voltage drops, make first triode Q1's base voltage decline, thereby make first triode Q1's collector current reduce, the effect of negative feedback has been realized, the stability of circuit has been increased.
In addition, the loads of the third triode Q3 and the fourth triode Q4 which are used as emitter followers are output buffer stages with large parasitic capacitance, and the emitter followers have large current driving capability, so that the time delay of high-speed signals on a transmission line with large parasitic capacitance can be reduced; in addition, from the aspect of frequency domain, when the second common emitter amplifying unit 3 is driven by the emitter follower, a conjugate pole is generated, and the bandwidth can be properly expanded.
For the circuit shown in fig. 5, the base of the first triode Q1 is electrically connected to the anode of the first photodiode D1, the base of the second triode Q2 is electrically connected to the anode of the second photodiode D2, the cathode of the first photodiode D1 and the cathode of the second photodiode D2 are input to the working power supply VDD, and the first photodiode D1 and the second photodiode D2 are the same photodiodes, and the photodiodes can convert an optical signal into a current signal, and then the current signal is converted into a voltage signal by the first common emitter amplifying unit 1, the feedback unit 2 and the second common emitter amplifying unit 3, wherein the principle of converting the current signal into the voltage signal refers to the content of the working flow of the circuit shown in fig. 4. In practical use, light is allowed to irradiate only the first photodiode D1, so that a sink current input to the base of the first triode Q1 can be generated, and specifically, an aluminum layer can be used to shield the second photodiode D2 so that the second photodiode D2 does not receive light.
In the circuit shown in fig. 5, since the first photodiode D1 and the second photodiode D2 are the same, when the first photodiode D1 is not illuminated by light, the first photodiode D1 and the second photodiode D2 generate the same dark current (the current generated by the photodiodes when the first photodiode D1 is not illuminated), and when the same dark current is input to the base of the first triode Q1 and the base of the second triode Q2, the final voltage output of the present invention is not affected, and the effects of two paths of dark current on the circuit are mutually offset, so that the present invention does not output an erroneous result.
In conclusion, the invention has the following beneficial effects:
a: the circuit adopts a fully differential structure, the input differential current signal is converted into a voltage signal and amplified through the first common emitter amplification unit 1, and the voltage signal is further amplified through the second common emitter amplification unit 3, so that high gain is realized;
b: the optical signal is converted into a current signal through the first photosensitive diode D1, the current signal is converted into a voltage signal through the first common emitter amplification unit 1 and amplified, and finally the voltage signal is further amplified through the second common emitter amplification unit 3, so that the conversion from the optical signal to the voltage signal is realized; by using the differential structure, the dark current generated by the second photodiode D2 can counteract the dark current generated by the first photodiode D1, thereby eliminating the influence of the intrinsic dark current of the photodiodes on the output result;
c: the circuit adopts a fully differential structure, the inherent high common mode rejection ratio can reduce the power supply fluctuation and the interference of a parasitic feedback path, and can inhibit the substrate coupling noise and temperature drift when the circuit is integrated on a substrate, thereby realizing low noise; in addition, a differential amplifier is needed to further amplify the two paths of second voltage signals in practical application, and the second common emitter amplifying unit 3 with the differential input structure is arranged to be conveniently cascaded with the differential amplifier, so that a single-end-double-end conversion circuit is not needed to be additionally added in the circuit, and monolithic integration is easy to realize;
d: a large bandwidth;
e: the whole circuit has simple structure and few devices, and reduces the power consumption and the chip area.
In a second aspect, the invention further provides an optical coupler chip, which includes the high common mode rejection transimpedance amplifier.
In light of the foregoing, it is to be understood that various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.
Claims (9)
1. A high common mode rejection trans-impedance amplifier is characterized by comprising a first common emitter amplification unit, a feedback unit and a second common emitter amplification unit; the first common emitter amplifying units are symmetrically arranged, comprise two first differential input ends, are configured to amplify input current signals and output two paths of first voltage signals; the feedback unit comprises two symmetrically arranged feedback branches, and the two feedback branches are electrically connected with the first common emitter amplification unit and used for feeding back two first voltage signals to two first differential input ends; the second common emitter amplifying units are symmetrically arranged and comprise two second differential input ends, two paths of first voltage signals are input into the two second differential input ends, and the second common emitter amplifying units are used for amplifying the two paths of first voltage signals and outputting two paths of second voltage signals.
2. The transimpedance amplifier according to claim 1, wherein the first common emitter amplifying unit comprises a first resistor R1, a second resistor R2, a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a first current source I1, a second current source I2, and a third current source I3;
one end of the first resistor R1 and one end of the second resistor R2 are configured to input a working power supply; the other end of the first resistor R1 is respectively and electrically connected with a collector electrode of a first triode Q1 and a base electrode of a third triode Q3, and the other end of the second resistor R2 is respectively and electrically connected with a collector electrode of a second triode Q2 and a base electrode of a fourth triode Q4; the emitting electrode of the first triode Q1 and the emitting electrode of the second triode Q2 are grounded through the first current source I1 respectively;
the collector of the third triode Q3 and the collector of the fourth triode Q4 are configured to an input working power supply; an emitting electrode of the third triode Q3 is grounded through a second current source I2, and an emitting electrode of the fourth triode Q4 is grounded through a third current source I3; and the emitting electrode of the third triode Q3 and the emitting electrode of the fourth triode Q3 output two paths of first voltage signals.
3. A high common mode rejection transimpedance amplifier according to claim 2, further comprising a first photodiode D1 and a second photodiode D2; the base electrode of the first triode Q1 is electrically connected with the anode of the first photosensitive diode D1, and the base electrode of the second triode Q2 is electrically connected with the anode of the second photosensitive diode D2; the cathode of the first photodiode D1 and the cathode of the second photodiode D2 are configured to input a working power.
4. A high common mode rejection transimpedance amplifier according to claim 2, wherein the resistance of the first resistor R1 is the same as the resistance of the second resistor R2, the width-to-length ratio of the first transistor Q1 is the same as the width-to-length ratio of the second transistor Q2, and the width-to-length ratio of the third transistor Q3 is the same as the width-to-length ratio of the fourth transistor Q4.
5. The transimpedance amplifier according to claim 1, wherein the feedback branch comprises a feedback capacitor and a feedback resistor;
one end of a feedback capacitor in one feedback branch circuit is electrically connected with one end of a feedback resistor and is configured to input one path of first voltage signals; the other end of the feedback capacitor and the other end of the feedback resistor in the feedback branch are respectively and electrically connected with a first differential input end;
one end of a feedback capacitor in the other feedback branch circuit is electrically connected with one end of a feedback resistor and is configured to input the other first voltage signal; and the other end of the feedback capacitor in the other feedback branch circuit and the other end of the feedback resistor are respectively and electrically connected with the other first differential input end.
6. The transimpedance amplifier according to claim 5, wherein capacitance values of the feedback capacitors in the two feedback branches are the same, and resistance values of the feedback resistors in the two feedback branches are the same.
7. The transimpedance amplifier according to claim 2, wherein the second common-mode rejection amplifying unit comprises a fifth resistor R5, a sixth resistor R6, a fifth transistor Q5, a sixth transistor Q6, and a fourth current source I4; one end of the fifth resistor R5 and one end of the sixth resistor R6 are configured to input a working power supply; the other end of the fifth resistor R5 is electrically connected with the collector of a fifth triode Q5, and the other end of the sixth resistor R6 is electrically connected with the collector of a sixth triode Q6; the emitter of the fifth triode Q5 and the emitter of the sixth triode Q6 are grounded through the fourth current source I4; the base electrode of the fifth triode Q5 is electrically connected with the emitting electrode of the third triode Q3, and the base electrode of the sixth triode Q6 is electrically connected with the emitting electrode of the fourth triode Q4.
8. The transimpedance amplifier according to claim 7, wherein the resistance of the fifth resistor R5 is the same as the resistance of the sixth resistor R6, and the width-to-length ratio of the fifth transistor Q5 is the same as the width-to-length ratio of the sixth transistor Q6.
9. An optocoupler chip, characterized in that it comprises a high common mode rejection transimpedance amplifier according to any of claims 1 to 8.
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| CN202321693165.2U CN220383034U (en) | 2023-03-14 | 2023-06-30 | High common mode rejection transimpedance amplifier and optocoupler chip |
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| US20100284703A1 (en) * | 2007-11-30 | 2010-11-11 | Yasuyuki Suzuki | Light receiving circuit and signal processing method |
| US20130028596A1 (en) * | 2010-04-21 | 2013-01-31 | Nec Corporation | Optical receiver, optical reception device, and correction method for optical received intensity |
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| US20150200635A1 (en) * | 2014-01-16 | 2015-07-16 | National Taiwan University Of Science And Technology | Operational transconductance amplifier, reconfigurable fully differential voltage sensing amplifier and reconfigurable fully differential capacitive sensing amplifier |
| CN208015693U (en) * | 2018-03-06 | 2018-10-26 | 厦门优迅高速芯片有限公司 | A kind of programmable equalizing circuit of low-voltage high speed |
| CN114124123A (en) * | 2021-11-17 | 2022-03-01 | 成都信息工程大学 | Broadband integrated CMOS global feedback receiver front-end circuit |
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2023
- 2023-03-14 CN CN202310237748.2A patent/CN115940855A/en active Pending
- 2023-06-30 CN CN202321693165.2U patent/CN220383034U/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100284703A1 (en) * | 2007-11-30 | 2010-11-11 | Yasuyuki Suzuki | Light receiving circuit and signal processing method |
| US20130028596A1 (en) * | 2010-04-21 | 2013-01-31 | Nec Corporation | Optical receiver, optical reception device, and correction method for optical received intensity |
| US20150200635A1 (en) * | 2014-01-16 | 2015-07-16 | National Taiwan University Of Science And Technology | Operational transconductance amplifier, reconfigurable fully differential voltage sensing amplifier and reconfigurable fully differential capacitive sensing amplifier |
| CN103840775A (en) * | 2014-02-27 | 2014-06-04 | 嘉兴禾润电子科技有限公司 | Limiting amplifier allowing direct-current offset eliminating function to be achieved on sheet |
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