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Fixed gain amplifier for automatic gain control and variable gain amplifier

A technology of automatic gain control and gain amplifier, which is applied in the field of communication systems and can solve the problems of unguaranteed constant output signal, poor adaptability, and changes in the performance of peak detector 114.

Inactive Publication Date: 2008-01-09
O2 MICRO INC
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, due to process, voltage and temperature (PVT) differences, the performance of the peak detector 114 will also vary
Therefore, the above two configurations of the AGC loop cannot ensure the precise control of the output signal IF_OUT
In addition, traditional fixed-gain amplifiers have poor adaptability to PVT differences, so the constant output signal IF_OUT is not guaranteed

Method used

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  • Fixed gain amplifier for automatic gain control and variable gain amplifier
  • Fixed gain amplifier for automatic gain control and variable gain amplifier
  • Fixed gain amplifier for automatic gain control and variable gain amplifier

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Embodiment Construction

[0030] FIG. 3 is a block diagram of a VGA circuit 200 provided by the present invention. The VGA circuit 200 includes an amplifying unit 202 made up of a variable gain amplifier 201 and a fixed gain amplifier 203, including an AGC loop 204 made up of a first peak detector 205-1 and a second peak detector 205-2, including a comparator 207 and loop filter 209 . The intermediate frequency signal IF_IN enters the amplifying unit 202 and passes through the variable gain amplifier 201 and the fixed gain amplifier 203 to obtain an output signal IF_OUT with a preset gain. Then the first peak detector 205-1 detects the output signal IF_OUT and generates a first peak signal Vpeak_1, which indicates the peak value of the output signal IF_OUT. Simultaneously, the second peak detector 205-2 (the peak detector is exactly the same as the peak detector 205-1) detects the reference signal Vref generated by the bandgap voltage reference circuit (not shown in the figure) and generates an indica...

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PUM

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Abstract

A variable gain amplifier (VGA) circuit and an automatic gain control (AGC) method thereof are disclosed. The VGA circuit includes an amplifier circuit and an AGC circuit. The amplifier circuit amplifies an input signal to an output signal according to a predetermined gain and the AGC circuit is connected to the amplifier circuit for regulating the predetermined gain. The AGC circuit further includes a peak detector detecting a peak of the output signal, a replica of the peak detector for detecting a peak of a reference signal, and a comparator for comparing the peak of the output signal with the peak of the reference signal to provide a control signal and then providing the control signal to the amplifier circuit to regulate the predetermined gain.

Description

technical field [0001] The invention relates to a communication system, in particular to a signal amplifying circuit and a gain control method in a radio frequency (RF) receiver. Background technique [0002] In communication technology, data is usually modulated into a signal and transmitted via a transmission channel. The receiving end restores the received signal into data. Depending on the length of the transmission path, the transmitted signal amplitude is attenuated. Since the length of the transmission path and the amplitude attenuation of the signal are generally unknown, the amplitude of the received signal is also uncertain. In order to demodulate the received signal into the original data, the receiver is usually equipped with a variable gain amplifier (VGA) circuit for amplifying the received signal. Traditional VGA circuits operate in an automatic gain control (AGC) loop to generate a constant-amplitude signal that is not determined by the received signal. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03G3/20H04B7/005
CPCH03F2203/45288H03G1/0029H03F2203/45418H03F3/45672H03F2203/45434H03F2200/453H03F2200/78H03F3/45659H03F2200/435H03F2203/30031H03F3/45188H03F2203/45424H03F3/45479H03F2203/45366H03F3/3022H03G3/3036H03F2203/45681H03F3/45197H03F3/45183
Inventor 陈斯德罗小勇
Owner O2 MICRO INC
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