2013射频宽带放大器设计报告分析.doc

射频宽带放大器 摘 要：本系统采用宽带电压反馈运放OPA690、压控增益放大器VCA810以及宽带电流反馈放大器THS3001结合的方式，实现了增益可调的射频宽带放大器。系统主要由四个模块构成：前置放大电路、压控增益放大电路、后级放大电路、单片机显示控制模块。压控增益放大电路以VCA810为核心，实现60dB的可调节范围；使用THS3001等运放进行电压放大使最大有效值达到1V；整个电路波形稳定、无明显失真，噪声电压小,通频带内增益平坦，较好得完成了基本部分和发挥部分的要求。 关键词：射频放大、宽带放大、压控增益、单片机控制 Abstract Adopting a combination of wideband voltage-feedback amplifier OPA690, voltage-controlled gain amplifier-VCA810, wideband current-feedback amplifier THS3001, the system can achieve a RF（RF-Radio frequency）broadband amplifier with adjustable gain. The system is consisted of four blocks: pre-amplifier circuit, voltage-controlled gain amplifier circuit, the latter amplifier circuit, MCU display control module. With a core of VCA810, the VGA circuit can achieve 60dB of gain adjustment range. Applying THS3001 etc. amplifier gains 1V of maximum effective value. The whole system has a feature of stable distortionless waveform, low noise and high gainflatness complete the design tasks, both the basic part and extended part. Keywords: Radio frequency amplification、bandwidth amplification、voltage controlled gain、single chip microcomputer control 目录 一、系统方案…………………………………………………………………………………………………............4 1.1方案比较与选择…………………………………………………………………………………………........4 1.1.1前置放大电路………………………………………………………………………………………….........4 1.1.2 压控增益放大电路…………………………………………………………………………………........4 1.1.3 后级放大电路…………………………………………………………………………………………........4 1.2方案描述…………………………………………………………………………………………………….........5 二、理论分析与计算………………………………………………………………………………………...........6 2.1 宽带放大器设计………………………………………………………………………………………........6 2.2 频带内增益起伏控制………………………………………………………………………………………..6 2.3 射频放大器稳定性………………………………………………………………………………………… …6 2.4增益调整…………………………………………………………………………………………………………….6 三、电路与程序设计…………………………………………………………………………………………………7 3.1电路设计…………………………………………………………………………………………………………….7 3.1.1前置放大电路与电路原理图…………………………………………………………………………..7 3.1.2压控增益放大电路与电路原理图…………………………………………………………………..7 3.1.3 后级放大电路与电路原理图……………………………………………………………………… .