Constant rail-to-rail input and differential output high-speed programmable gain amplifier

Abstract

The invention discloses a constant rail-to-rail input and differential output high-speed programmable gain amplifier, which is mainly used for meeting the amplification requirement of a signal chain system on a high-frequency signal, reducing the harmonic distortion of the high-frequency signal and transmitting the high-frequency signal to a rear-end high-speed analog-to-digital converter. A gain amplifier structure is formed by cascading two constant gm single-ended output operational amplifiers serving as a first stage and a constant gm differential output operational amplifier serving as a second stage, and an input signal adjusts the proportion of a feedback resistor according to an external gain selection signal, so that the signal is amplified to a target gain. Therefore, the device has the advantages of good linearity, high speed, constant gm, real-time amplification and the like.

Description

technical field [0001] The invention belongs to the technical field of integrated circuits, and in particular relates to a high-speed programmable gain amplifier with constant cross-rail-to-rail input and differential output. Background technique [0002] The analog front end is the core module for processing analog signals in the signal system. It is widely used in data acquisition systems, sensors, radar communications, etc., and is a bridge connecting analog circuits and digital circuits. The analog front-end signal detects and amplifies the natural analog signal, and then converts it into an easy-to-handle digital signal through the analog-to-digital converter, and sends it to the digital system for processing; and the programmable gain amplifier (Programmable Gain Amplifier, PGA) is the analog front-end module. One of the core components, it can amplify the signal to different multiples according to the size of the input signal to improve the dynamic range of the system...

AI Technical Summary

Problems solved by technology

However, this structure can only be a single-ended output, and it is mostly used to amplify low-frequency signals. If high-frequency signals are amplified, there will be large gain errors and obvious harmonic distortion.

[0005] On the other hand, the traditional programmable gain amplifier has a certain range limitation on the common-mode voltage of the input signal, so when the input common-mode voltage is close to the power supply voltage or ground, the programmable gain amplifier cannot work normally, and when the input signal’s When the common-mode deviation is large, the gain of the amplifier will fluctuate accordingly; for analog signals in nature, because the common-mode voltage is not constant, the performance of the programmable gain amplifier will be unstable, which is not conducive to the application of integrated systems.

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