Linear High Rate The Consistency Agc Multi-channel If Receiver

As the rapid development of wireless communication technology especially the modern modulation system and microwave integrated circuits, wireless communication receiver applies widely in so many areas such as wireless communication, television broadcasting, radar positioning, remote sensing remote control, satellite communication and mobile communication and so on. In the design and implementation, the wireless receiver is asked tend towards high performance and high integration. And the modern receiver is asked in pursuit of good linearity, big dynamic range, high anti-interference and adaptative ability and so on. That extremely promotes the development of IF receiver has led to its increasing complexity, requesting to achieve more of its functions and more applies in the multi-channel. With the proposal of "Software radio", the modular design and systematic design of IF receiver is very necessary.The use of time-separated principle, pulse Doppler system is able to solution the problem of transmitter-Receiver isolation. It has the distance resolution in the pulse system, and has the velocity resolution in the CW system. And it has a high clutter rejection, so it can detect a moving target echo even in a strong clutter.This paper describes a kind of IF receiver that was developed the author. The receiver was used in pulse Doppler receiving system. Not only asked high sensitivity, big dynamic range,good selectivity,excellent amplitude-phase consistency between I/Q channels and high amplitude-phase consistency between channels and so on, but also realized blocking control, automatic gain control(AGC), quadrature(I/Q) demodulation, peak detection and many other features.By analyzing the noise characteristics and matching network, this text studies the various indicators of the receiver, and proposes the major factors about the impact on the receiver performance:the receive path self-excitation, channel inter-crosstalk, switching overshoot, amplitude-phase inconsistency of multi-channel AGC control, instability of AGC control, amplitude-phase inconsistency between I/Q channels and so on. To ensure the key performance indicators such as linearity, high amplitude-phase consistency, consistency and stability of AGC control, can meet the system requirements, we put forward and effectively apply the following key technologies:(1) High amplitude-phase consistency of multi-channel AGC control technology:including high amplitude-phase consistency between I/Q channels, high amplitude-phase consistency between channels, high amplitude-phase consistency of AGC control;(2) Cascade of AGC control technology:use of complementary characteristics with temperature forward and reverse AGC control components make up the circuit with cascade of AGC control;(3) Quadrature demodulation of matching technology : the quadrature demodulator's output port designed with impedance matching network, although placed between the front and the back circuit unit with different of their impedance characteristics, to ensure that still has a high-precision orthogonal features.The multi-channel receiver combined the large dynamic linear AGC module with the analog quadrature demodulation module. It has a high amplitude-phase consistency between channels and an excellent orthogonal feature in the pass-band and so on.