Bipolar transistor amplifier

Abstract

The invention discloses a bipolar transistor amplifier which comprises a bipolar transistor amplifying circuit, an amplifier input geminate transistor virtual mirror image geminate transistor, an input geminate transistor and mirror image transistor bias current circuit thereof, a virtual mirror image geminate transistor base current generation and mirror image circuit and an amplifier input geminate transistor working point tracking circuit. The base, collector and emitter voltages of the amplifier input geminate transistor virtual mirror image geminate transistor are consistent with the corresponding node voltage of the input-stage geminate transistor, so that the beta values of the two geminate transistors can be accurately matched without being influenced by factors such as the working voltage, process angle, temperature and input common mode, finally, it can be ensured that the base current of the input geminate transistor virtual mirror image geminate transistor is accurately equal to the base current of the input geminate transistor.

Description

technical field [0001] The invention belongs to the field of electronic technology, and in particular relates to a design method for a bipolar input-pair tube amplifier that realizes ultra-low external input bias current through an internal input current bias technology. Background technique [0002] General-purpose amplifiers play a pivotal role in today's electronic circuit design. Common amplifiers mainly include CMOS input-to-tube amplifiers, bipolar input-to-tube amplifiers, and JFET input-to-tube amplifiers. [0003] The amplifier with CMOS device as the input pair tube has the advantages of high input impedance and small input bias current; however, due to the characteristics of poor matching and high noise of CMOS devices, CMOS amplifiers usually face large DC offset, poor flicker noise, and gain bandwidth. Low challenge; bipolar transistors have the advantages of good matching, low noise, and high speed, but bipolar devices require base bias current, so bipolar amp...

AI Technical Summary

Problems solved by technology

[0006] 1. The current mirror image ratio error composed of MOS transistors M6 and M7: Due to the poor matching characteristics of MOS devices, the matching accuracy of the current mirror is poor, and the ideal internal current bias requires the current ratio of transistors P1, P2, and P3 to be accurately set Current ratio, MOS current mirror matching error will directly limit the internal bias effect

[0007] 2. The current mirror image ratio error composed of MOS transistors M1, M2, and M3: the internal current bias requires M1, M2 to accurately match the current of M3. The same principle as above, the poor matching characteristics of MOS devices will directly limit the internal bias Effect

For transistors with ultra-low base width modulation effects, this operating point tracking is not important, but for ordinary standard BCD processes, due to the base width modulation effects of bipolar transistors, β is significantly affected by Vce voltage, so Limits the mirror image accuracy of the P3 base current to the P1 and P2 base currents, and ultimately affects the effect of the internal current bias

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