High Speed ​​Programmable Gain Amplifier with Constant Across Rail-to-Rail Input Differential Output

Abstract

The invention discloses a high-speed programmable gain amplifier with constant cross-rail-to-rail input differential output, which is mainly used to meet the amplification requirements of high-frequency signals in a signal chain system, reduces the harmonic distortion of high-frequency signals, and reduces the harmonic distortion of high-frequency signals. It is transmitted to the back-end high-speed analog-to-digital converter. The structure of the gain amplifier of the present invention is formed by cascading two operational amplifiers with constant gm single-ended output as the first stage and one operational amplifier with constant gm differential output as the second stage, and the input signal adjusts the ratio of the feedback resistance according to the external gain selection signal, Thereby amplifying the signal to the target gain. Therefore, the present invention has the advantages of good linearity, high speed, constant gm, and real-time amplification.

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 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. It is a bridge connecting analog circuits and digital circuits. The analog front-end signal detects and amplifies the analog signal in nature, and then passes through the analog-to-digital converter, converts it into a digital signal that is easy to process, and sends it to the digital system for processing; while the Programmable Gain Amplifier (PGA) is an analog front-end module. One of the core components, it can amplify the signal to different times according to the size of the input signal to improve the dynamic range of the system. [0003] Today, a...

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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 voltage deviation is large, the gain of the amplifier will also 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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