| In the daily life radios, a number of precision measuring instruments and automaticcontrol system always have a variety of amplifier circuit. In these electronic equipmentamplifier circuits amplify can amplify weak biological signals, and the weak signal ofelectronic equipment, communications equipment and sensor to meet the follow-up devices.Operational Amplifier with negative feedback is often used to amplify low-frequency signaland high frequency signals. When amplifiers amplifie the low frequency signal, the frequencyresponse is very well. However, when they amplifie the high frequency signal, with theincreased gain of the amplifier, the signals band become narrower and narrower. Therefore, inmulti-level amplifier; how to amplify high frequency signal and at the same time effectivelybroadening signal broadband has become a prominent problem.Based on the analysis of Operational Amplifier for the application demand, whenmaking production of amplifiers how to amplify high frequency signals broadeningbroadband and making use of ultrafast and in-circuit programmable characteristics of FieldProgrammable Gate Array—FPGA then the paper design a broadband DC amplifier based onFPGA. The basic design principle is that it makes use of microcontroller AT89S52as microcontroller and makes use of FPGA-EP2C8Q208C8N to complete peak data collection andprocess. Amplifier circuit is composed of the three parts of the preamplifier, automatic gaincontrol and power amplification. The output voltage of the system passes through the RMSdetection circuit to the A/D converter circuit; A/D converter converted the analog voltageRMS into digital signals and sent them to FPGA to compare them with the initial sample peak.If the output signal is weak or strong, then it makes the difference between the two peaks as abasis for the gain adjustment of controlled gain amplifier, the data enter the D/A converter,and the control voltage of D/A output is sent to controlled gain amplifier, so it can achieveadjustable gain control, make sure the output value reaches the preset value, broaden thehigh-frequency bandwidth of the broadband DC amplifier, and amplify high frequency signalwith the DC amplifier forming a closed loop control system. The broadband DC amplifier is alow cost, wide bandwidth, big gain and dynamic range applies to a variety of occasions, andhas a good prospect. This paper describes the development of broadband DC amplifier and its main technicalindicators, advances a few design project to achieve the system goals, analyses the feasibleproject, combined with EDA software give computer function simulation for the amplifiercircuit, realizes data acquisition and control, storage control, trigger control and othercomplex logic contro by VHDL. Then it debugs for real amplifier, simulates and debugsagain and again. Finally the amplifier can meet the specifications in the results of computersimulation. The paper also refers to several problems that need attention when designingbroadband DC amplifier. At last, the paper gives the design of broadband DC amplifier andthe summary and prospects of broadband DC amplifier in the future. |
