CN-115580237-B - 25Gbps transimpedance amplifier for improving overload performance by adopting current compensation

Abstract

The invention discloses a 25Gbps transimpedance amplifier for improving overload performance by adopting current compensation, wherein a current compensation circuit CMP is a part of the 25Gbps transimpedance amplifier, and a main link of the transimpedance amplifier consists of a core amplifier Tia_core, a single-ended differential amplifier S2D, an output Buffer, an automatic gain adjustment circuit AGC, a current compensation circuit CMP and a mirror transimpedance amplifier dummy_tia module. The input current signal is converted into a single-ended voltage signal through the core amplifier Tia_core, then the single-ended signal voltage is converted into a differential voltage through the single-ended differential amplifier S2D, the differential signal is transmitted to the next chip by the output Buffer, the impedance matching in the transmission process is ensured, and the gain of the core amplifier Tia_core circuit is automatically adjusted by the automatic gain adjusting circuit AGC according to the input current amplitude.

Inventors

• ZHANG HAO
• LIN JIAHUI
• SHI JIAPENG

Assignees

• 南京美辰微电子有限公司

Dates

Publication Date

20260505

Application Date

20221028

Claims (4)

1. 1. The 25Gbps transimpedance amplifier adopting current compensation to improve overload performance is characterized by comprising a core amplifier Tia_core, a single-ended differential amplifier S2D, an output Buffer, an automatic gain adjustment circuit AGC, a current compensation circuit CMP and a mirror transimpedance amplifier Dummy_tia; the core amplifier tia_core is configured to convert an input current signal into a single-ended voltage signal; The single-ended to differential amplifier S2D is used for converting single-ended signal voltage into differential voltage; The automatic gain adjusting circuit AGC is used for adjusting the gain of the core amplifier Tia_core circuit according to the current amplitude from the single-ended differential amplifier S2D; the current compensation circuit CMP is used for compensating current for the Tia_core circuit of the core amplifier when a large current signal is input; The Voutp1 output end of the core amplifier Tia_core is connected with the positive input end of the single-ended rotary differential amplifier S2D, and the Voutn1 output end of the mirror image transimpedance amplifier Dummy_tia is respectively connected with the negative input end of the single-ended rotary differential amplifier S2D and the positive input end of the current compensation circuit CMP; the negative electrode input end of the current compensation circuit CMP is connected with a preset reference voltage Vref, the VG output end of the current compensation circuit CMP is respectively connected with the VG input end of the core amplifier Tia_core and the VG input end of the mirror image transimpedance amplifier Dummy_tia, the negative electrode output end of the single-ended differential amplifier S2D is respectively connected with the negative electrode input end of the output Buffer and the negative electrode input end of the automatic gain adjustment circuit AGC, the positive electrode output end of the single-ended differential amplifier S2D is respectively connected with the positive electrode input end of the output Buffer and the positive electrode input end of the automatic gain adjustment circuit AGC, the vb_sig output end of the automatic gain adjustment circuit AGC is respectively connected with the vb_sig input end of the core amplifier Tia_core and the vb_sig input end of the mirror image transimpedance amplifier Dummy_tia, and the vb_vga output end of the automatic gain adjustment circuit AGC is respectively connected with the vb_vbga input end of the core amplifier Tia_core, and the vb_vga input end of the mirror image transimpedance amplifier Dummy_tia, and the output end of the output Buffer is simultaneously connected with the output end of the VCC1 through the positive electrode resistor Ra as the output end of the VCC amplifier; The current compensation circuit CMP comprises an operational amplifier OP, a resistor R9, and a current source Iref, wherein the negative input end of the operational amplifier OP is respectively connected with one end of the resistor R9 and one end of the current source Iref, the other end of the resistor R9 is connected with the power VCC, the other end of the current source Iref is grounded, and the positive input end of the operational amplifier OP is used as the positive input end of the current compensation circuit CMP.
2. 2. The 25Gbps transimpedance amplifier for improving overload performance by current compensation according to claim 1, wherein the core amplifier Tia_core circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor Rf1, a transistor Q2, a transistor Q3, a transistor Q4, a transistor Q5 and a MOS transistor M1, wherein an input terminal of the core amplifier Tia_core circuit is respectively connected with a base of the transistor Q1 and one end of the resistor Rf1, an emitter of the transistor Q1 and one end of the resistor R1 are commonly grounded, an S electrode of the MOS transistor M1 is commonly connected with an input terminal of the core amplifier Tia_core, a G electrode of the MOS transistor M1 is commonly connected with an emitter of the transistor Q3, a base of the transistor Q3 is respectively connected with the transistor Q2 and one end of the resistor R3, a base of the transistor Q5 is respectively connected with an external voltage Vb1, an emitter of the transistor Q2 is respectively connected with one end of the resistor R4, another end of the resistor R3 and another end of the resistor R4 is commonly connected with an emitter of the resistor R4, and another end of the MOS transistor M1 is commonly connected with an emitter of the resistor R4 as an emitter of the core amplifier, and another end of the MOS transistor M1 is commonly connected with an emitter of the resistor.
3. 3. The 25Gbps transimpedance amplifier for improving overload performance with current compensation according to claim 1, wherein the mirrored transimpedance amplifier dummy_tia circuit comprises a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor Rf2, a transistor Q6, a transistor Q7, a transistor Q8, a transistor Q9, a transistor Q10, a MOS transistor M2; the base of the transistor Q10 is connected with one end of a resistor Rf2, the emitter of the transistor Q10 is commonly grounded with one end of a resistor R6 and the S electrode of the MOS transistor M2, the G electrode of the MOS transistor M2 is used as the VG input end of a mirror transimpedance amplifier Dummy_tia, the other end of the resistor R6, the other end of the resistor Rf2 and the D electrode of the MOS transistor M2 are commonly connected with the emitter of a transistor Q9, the base of the transistor Q9 is respectively connected with the collector of a transistor Q7 and one end of a resistor R8, the base of the transistor Q7 is connected with an external voltage Vb1, the emitter of the transistor Q7 is respectively connected with the collector of the transistor Q10 and one end of a resistor R5, the other end of the resistor R8, one end of the resistor R7 and the collector of the transistor Q6 are commonly connected with a power VCC, the base of the transistor Q6 is used as the vb_vg input end of the mirror transimpedance amplifier Dummy_tia, the emitter of the transistor Q6 is respectively connected with the emitter of the transistor Q9, the base of the transistor Q8 is used as the vb_sig input end of the core amplifier Tia_core, and the other end of the resistor R8 is connected with the collector of the resistor R7 is used as the output end of the mirror transimpedance amplifier Dummy_1.
4. 4. The 25Gbps transimpedance amplifier for improving overload performance by current compensation according to claim 1, wherein the automatic gain control circuit AGC comprises a resistor R10, a resistor R11, a resistor R12, a resistor R13, a capacitor C1, an NMOS tube M3, an NMOS tube M6, an NMOS tube M7, a PMOS tube M4, a PMOS tube M5 and a current source I1, wherein the G pole of the NMOS tube M6 is used as the positive input end of the automatic gain control circuit AGC and is connected with a power supply Vcm through the resistor R10, the G pole of the NMOS tube M7 is used as the negative input end of the automatic gain control circuit AGC and is connected with a power supply Vcm through a resistor R11, the S pole of the NMOS tube M6, one end of the current source I1 and one end of the capacitor C1 are commonly connected to the S pole of the NMOS tube M3, the other end of the current source I1 and the other end of the capacitor C1 are commonly grounded, the G pole of the NMOS tube M3 is connected with one end of the resistor R13, the D pole of the NMOS tube M5 is connected with the D pole of the NMOS tube M6 as the positive input end of the automatic gain control circuit AGC, the connection point is used as the connection point of the positive input end of the automatic gain control circuit AGC, and the connection point of the G pole of the NMOS tube M6 is connected with the other end of the PMOS tube M4 is commonly connected with the output end of the PMOS tube, and the output end of the AGC pole 12 is commonly connected with the output end of the AGC.

Description

25Gbps transimpedance amplifier for improving overload performance by adopting current compensation Technical Field The invention belongs to the technical field of microelectronics, and particularly relates to a 25Gbps transimpedance amplifier for improving overload performance by adopting current compensation. Background With the increase of the requirement of users on the network downloading rate, the 5G communication puts higher requirements on the bearer network, such as large capacity, long distance, high bandwidth, low delay, large connection, etc. As can be seen from the network architecture of the 5G carrier network (forward, mid-transmission, and return), a large number of optical modules are needed between RRU and DU to carry 5G forward traffic, and large-scale deployment of macro base stations and small base stations will bring about a large demand for optical modules, where core electrical chips in the optical modules include a transimpedance amplifier (TIA) chip that converts the high-frequency current output by the photodiode into a differential voltage, and a transceiver chip that continues to process the output signal of the transimpedance amplifier (TIA), and a typical bit rate of the processed signal is 25Gbps. The transimpedance amplifier chip is positioned at the forefront end of the signal link and is particularly sensitive to noise and the dynamic range of input current, when the input current is in uA level small signals, the performance of the transimpedance amplifier mainly depends on equivalent noise and link bandwidth, and when the input current is up to mA level large signals, a large signal regulating circuit is required to be designed for avoiding signal distortion caused by the oversaturation of the transimpedance amplifier link, and the overload performance of the transimpedance amplifier mainly depends on a large signal compensating circuit. Disclosure of Invention The invention aims to provide a 25Gbps transimpedance amplifier with current compensation for improving overload performance, wherein a current compensation circuit CMP (chemical mechanical polishing) contained in the transimpedance amplifier can effectively avoid signal distortion caused by excessive saturation of a transimpedance amplifier link when an input current signal is a large signal with a level up to mA, and greatly improve the overload performance of the transimpedance amplifier. The invention provides a 25Gbps transimpedance amplifier for improving overload performance by adopting current compensation, which comprises a core amplifier Tia_core, a single-ended differential amplifier S2D, an output Buffer, an automatic gain adjusting circuit AGC, a current compensating circuit CMP and a mirror transimpedance amplifier Dummy_tia, wherein the core amplifier Tia_core is used for converting an input current signal into a single-ended voltage signal, the single-ended differential amplifier S2D is used for converting the single-ended signal voltage into a differential voltage, the automatic gain adjusting circuit AGC is used for adjusting the gain of a core amplifier Tia_core circuit according to the current amplitude from the single-ended differential amplifier S2D, and the current compensating circuit CMP is used for compensating the current of the core amplifier Tia_core circuit when a large current signal is input; The Voutp1 output end of the core amplifier Tia_core is connected with the positive input end of the single-ended rotary differential amplifier S2D, and the Voutn1 output end of the mirror image transimpedance amplifier Dummy_tia is respectively connected with the negative input end of the single-ended rotary differential amplifier S2D and the positive input end of the current compensation circuit CMP; the negative electrode input end of the current compensation circuit CMP is connected with a preset reference voltage Vref, the VG output end of the current compensation circuit CMP is respectively connected with the VG input end of the core amplifier Tia_core and the VG input end of the mirror image transimpedance amplifier Dummy_tia, the negative electrode output end of the single-ended differential amplifier S2D is respectively connected with the negative electrode input end of the output Buffer and the negative electrode input end of the automatic gain adjustment circuit AGC, the positive electrode output end of the single-ended differential amplifier S2D is respectively connected with the positive electrode input end of the output Buffer and the positive electrode input end of the automatic gain adjustment circuit AGC, the vb_sig output end of the automatic gain adjustment circuit AGC is respectively connected with the vb_sig input end of the core amplifier Tia_core and the vb_sig input end of the mirror image transimpedance amplifier Dummy_tia, and the vb_vga output end of the automatic gain adjustment circuit AGC is respectively connected with the vb_vbga input end of the core amplifier Ti