High-bandwidth transimpedance amplifier suitable for low noise and wide dynamic range

Abstract

The invention relates to the electronic field and discloses a high-bandwidth transimpedance amplifier suitable for a low noise and a wide dynamic range. The amplifier comprises a variable gain amplification circuit and a variable feedback resistor which form multistage cascade. The variable gain amplification circuit can provide a high gain and simultaneously effectively solves a loop stability problem brought by the wide dynamic range through the tenability of the gain. The amplification circuit adopts the input structure of a common source structure so as to effectively restrain the influence of a rear-grade circuit noise. In addition, a transimpedance amplifier structure is suitable for various manufacturing technologies and is also suitable for the design of an optical-communication front-end transimpedance amplifier.

Description

technical field [0001] The present invention relates to the field of electronics, in particular to amplifier technology. Background technique [0002] The traditional resistance feedback type transimpedance amplifier circuit is as follows figure 1 As shown, a jumper resistor is connected between the input terminal and the output terminal of the operational amplifier A(s). Under the requirement of wide dynamic range, that is, when RF changes from tens of thousands of ohms to tens of ohms, the operational amplifier A(s) s) and the closed-loop structure composed of the feedback resistor RF has the defect that the stability of the loop is difficult to be guaranteed in the application. [0003] The traditional high-gain, low-noise transimpedance amplifier adopts a cascode structure, and its circuit diagram is as follows: figure 2 As shown, the transimpedance amplifier can increase the gain, and the common gate structure adopted by the circuit can reduce the Miller effect of th...

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Problems solved by technology

[0004] In practical applications, when the above-mentioned cascode amplifier and feedback resistor constitute a transimpedance amplifier, because the frequency response characteristics of the cascode circuit, including gain and pole position, will not change due to changes in the feedback resistor, when the feedback resistor When the range of change is severe, the closed-loop system loses stability at certain specific feedback resistance values, that is, the phase margin of the closed-loop system changes drastically, and even zero phase margin occurs

[0005] In addition, the impedance of the output node of the cascode amplifier is relatively high, and a low-frequency pole may be generated on this node, so that there are two relatively low-frequency poles after the closed loop (the other low-frequency pole is at the input of the op amp, determined by Feedback resistor, input node capacitive load), so the stability of the circuit is difficult to be guaranteed

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