Design Of 0?50MHz Automatic Gain Control Amplifier Based On 22nm CMOS Process

Since the invention of radio technology at the end of the 19th century,the receiver has been a basic module of long-distance communication systems,and has played a vital role in the third communication revolution characterized by modulated waves and electronic signals.With the rapid development of wireless communication systems,people have higher and higher requirements for receivers and transmitters.In a wireless communication system,due to the influence of various factors such as environment and noise,the strength of the communication signal may be strong and weak,resulting in a wide range of amplitude of the receiver input signal.In order to receive the signal accurately,the receiver usually needs to be equipped with an automatic gain control circuit(Automatic Gain Control,AGC).As an important module of the RF front-end,the performance of AGC directly affects the performance of the receiver.Therefore,the design of AGC with wide gain control dynamic range,high linearity and low noise has important research significance and practical value.In this paper,an AGC circuit with an RF front-end receiver is designed based on the 22nm CMOS process,and the operating frequency is 0-50MHz.The AGC circuit is mainly composed of four modules:variable gain amplifier(Variable Gain Amplifier,VGA),peak detector(Peak Detector,PD),error amplifier and loop filter.The VGA module adopts a source-level feedback resistor structure,and the introduction of the feedback resistor can improve the linearity of the VGA.In order to achieve a gain control dynamic range greater than 30dB,a four-stage cascade method is adopted.The PD module is mainly composed of a comparator and a current mirror,and detects the peak value of the VGA output signal.The error amplifier compares the result of the peak detection with the reference voltage and generates a control voltage to control the gain of the VGA until the result of the peak detection is equal to the reference voltage,and the loop reaches a steady state.The loop filter determines the settling time of the AGC loop.In order to prevent error and inverse modulation,the loop settling time needs to be kept moderate.When the power supply voltage is 1V,the post-simulation results of the AGC system show that the automatic gain control range of the AGC system is greater than 35dB,the output 1dB compression point is greater than 0dBm,and the third-order intermodulation is output under the tt process angle and the temperature is between-40?85?.The point is greater than 10dBm,the noise figure is less than 13dB,the average operating current is less than 13m A,and the core area is about 90*70?m~2.All performances meet the index requirements.The AGC system designed in this article can be applied to wireless receivers.The frequency band of AGC can be adjusted by adjusting the charge and discharge capacitors of the peak detector and loop filter,and it can be flexibly applied to receivers in other frequency bands.