Research And Design Of Key Circuits In 130nm CMOS X-Band Radar Receiver

Radar receiver is responsible for signal reception and processing in communication systems.The low noise amplifier and mixer are located at the first and second stages of the receiver,respectively,and have great influence on the overall gain,noise,and even linearity of the receiver.Based on 130nm CMOS process,this article has studied on the matching,noise,linearity,and gain of two key circuits.The main work content and innovations are as follows:1.This article analyzes the wideband matching network and noise of low noise amplifiers.A load realization and load dual resonance method based on noise cancellation structure is designed.The two branches at the output end reversely cancel the noise.A drain inductance and a parasitic capacitance forms the high impedance.So,it can reduce the noise contribution of the load,while eliminating the common gate circuit noise.The second LC dual-resonant load broadens the gain bandwidth.The LNA simulation results,based on this structure,show that the noise figure is reduced from 4.6dB to 3.36dB,and the highest gain reaches 15.1dB within the 7.8-11.3GHz gain bandwidth.The common-gate input achieves an input matching bandwidth of 7.7-11.4GHz,and S11 is less than-10dB.2.Aiming at the poor linearity and narrow matching bandwidth of the common-source low-noise amplifier,a sub-threshold distortion structure with low power consumption and wideband linearity improvement technology is proposed.With this technology,an X-band low-power enhanced low-noise amplifier is designed.In the X-band,only the additional power of 0.075mW of the sub-threshold auxiliary circuit is introduced,but the input third-order intermodulation point is increased from-13?-4 dBm to-5.2-4 dBm through the current superposition effect,with an increase range of 5 to 16 dBm.Morever,aiming at the narrow bandwidth of common source matching,a load-optimized common source broadband matching method was designed.Simulation results show that,while simplifying the input network,the circuit has a wideband match with S11 less than-8dB in the X-band.With the load resonance network,a gain bandwidth of 8-12GHz is achieved with a maximum gain of 14dB.And according to the cascaded noise characteristics,the low noise amplifier achieves a noise figure of 1.86dB.3.After analyzing the noise contribution and linearity of the mixer,this paper performs noise suppression and linearity optimization on the traditional Gilbert structure.A double-balanced mixer with linear boost noise reduction in the X-band was designed.A sub-threshold low-distortion linear power-lifting structure is used to eliminate the non-linearity of the transconductance stage through nonlinear superposition.Moreover,using the inductor with virtual ground,while reducing the area,the resonance eliminates the third-order intermodulation term introduced by the parasitic capacitances of the switch pairs.The structure,combined with a self-biasing current injection structure and a common source inductor,is used to decrease the current and parasitic effects of the switch,so it also reduces the mixer noise figure.Simulation results show that the mixer of this structure achieves better isolation of each port,and its input third-order intermodulation point is increased from 0.5dBm to 5.5dBm.At 10MHz IF,the noise figure of the mixer is reduced from 17.2dB to 10.9dB.When the local oscillator signal amplitude is 4dBm,a conversion gain of 19dB is achieved.