Design Of Broadband Programmable Gain Amplifier Module

In the field of signal detection,due to the relatively large dynamic range of the original signal and irregular fluctuations in the signal amplitude range,it is necessary to randomly change the gain of the amplifier to automatically adapt to the wide-ranging analog signal,in order to enable the amplifier to accurately control the amplification factor and achieve programcontrolled gain amplification,and the step control of the amplification factor is within a small range.The programmable gain amplifier module designed in this paper works in a dual-mode mode.The first mode is a fixed gain output signal variable mode,and the second is a fixed gain output signal variable mode.The amplifier module uses STM32F407ZGT6 as the microcontroller.The microcontroller and the multi-stage variable gain amplifier,fixed gain amplifier,and peak detection circuit form a closed loop control to form an automatic gain control circuit.Firstly,the signal output by the peak detection circuit is collected by AD,and then the whole module is in a dynamic balance state after DA feedback.This closed-loop control system can accurately control the gain and output signal,test the experimental data and verify the results.The host computer and the programmable gain amplifier module communicate through the USB-RS232 serial port to realize human-computer interaction.Experimental results show that the module can achieve gain control of-20 d B?60d B in the frequency range of 1k Hz?20MHz;when the gain is fixed,the relative error of the gain is within 3.0%;when the output voltage is fixed,the relative error of the voltage is within 3.0%,and the test result is up to the requirements of indicator design.Compared with the traditional program-controlled amplifier module,this module has the following advantages:(1)The upper computer software uses the MFC user interface under the Visual Studio platform to design its own upper computer software control interface.This software control interface can mount multiple hardware modules to lay a solid foundation for the subsequent software control interface.The human-computer interaction between the host computer and the program-controlled gain amplifier module can complete information processing and management for the purpose of people's wishes to the greatest extent,so that the programcontrolled gain amplifier module can be separated from the independent working mode,It is more scientific to mix into the intelligent instrument for human-computer interaction.(2)This module achieves the performance indicators of broadband,high precision and high gain,and takes into account and optimizes the three performance indicators at the same time.Compromise consideration of performance indicators to make it no longer single.It also lays the foundation for the integration of the programmable gain amplifier module and standardizes the module,miniaturization and intelligence.