Preamplifier capable of processing bipolar signals

Abstract

The invention discloses a preamplifier capable of processing bipolar signals. The preamplifier is characterized by comprising a core amplification circuit and a feedback circuit, wherein the core amplification circuit comprises a cascode amplifier (1) serving as an input stage, a source follower (3) serving as a second stage, a biasing circuit (4), a first biasing current source (2), a second biasing current source (5) and a third biasing current source (6); the input stage is connected in parallel with the first bias current source (2) and is used for increasing the working current of the input stage; a feedback capacitor is connected between the input stage and the second stage and is used for adjusting the closed-loop gain of the pre-amplifier; the bias circuit (4) is connected with the input stage and provides bias voltage for a common-gate tube of the cascode amplifier (1); and the feedback circuit comprises an equivalent feedback resistance branch (7) used for discharging charges of the integral voltage of the feedback capacitor and an input leakage current equivalent feedback inductance branch (8) used for absorbing the backflow pre-amplifier.

Description

technical field [0001] The invention belongs to the technical field of electronics and relates to a preamplifier capable of processing bipolar signals. Background technique [0002] In our daily production and scientific research, it often happens that we need to receive a weak voltage signal from the signal source. At this time, we need to use the preamplifier to perform one-stage pre-amplification processing to improve the signal-to-noise ratio of the circuit. Under the premise of low noise, it is sent to the subsequent stage circuit for the next step of signal processing. For example, in common audio amplifiers, the sound signal picked up by the microphone is usually relatively weak, and it needs to be amplified to a certain level before being passed to the subsequent circuit; in addition, in terms of scientific research, the readout system of high-energy physics experiments and other nuclear radiation In the measurement, the signal output by the detector is often relati...

AI Technical Summary

Problems solved by technology

[0003] With the continuous update and iteration of the integrated circuit manufacturing process, the operating voltage of its circuit is also continuously reduced. It is a great challenge. Therefore, limited by the power supply voltage, the preamplifier circuit will only be optimized for a specific polarity signal, such as adjusting the operating point of the circuit for negative polarity input signals to adapt to a larger input dynamic range. As well as the optimization of noise performance and the design of compensation structure for leakage current, etc., this also makes it difficult for the preamplifier circuit to take into account the preamplification of the two polarity input signals, because the excessive swing of the input signal will lead to the DC operating point of the amplifier circuit changes, and then loses the characteristics of saturation amplification, which leads to the limitations of the application range of the existing preamplifier circuit, that is, it can only be applied to positive polarity input signals or negative polarity input signals, and there are relatively large application limitations. sex

In addition, if the requirements for the performance indicators of the preamplifier circuit remain the same, but the input signal is changed from a positive swing to a negative swing, then to a large extent the core circuit structure is similar or even remains the same, but the circuit The feedback structure is adjusted and optimized accordingly. Based on this prerequisite, in order to adapt to the input signals of two polarities, designing two preamplifier circuits with similar core circuit structures and slightly different feedback structures will cause design resources and manpower. great waste of cost

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