Research On Silicon-based Millimeter-Wave Attenuator And Limiting Amplifier Integrated Circuits

With the development of modern communication technology and semiconductor technology,the research of integrated circuit becomes more and more important.As amplitude control circuits,attenuators and amplifiers are widely used in communication systems.Digital attenuator is an important part of the transceiver module of active phased array radar system,and it controls the number and direction of radar beam together with digital phase shifter.So it is very important to study digital attenuator and improve its performance for active phased array radar system.The limiting amplifier can be used in terahertz receiver,which is usually used to amplify and limit the signal so as to realize the shaping and protection of the signal,so as to drive the back circuit to work normally.This thesis is divided into two modules:digital attenuation integrated circuit and limiting amplifier integrated circuit.The digital attenuation integrated circuit includes two sub-designs:A Compact Ku-Band 6-bit Attenuator and DC~70GHz ultra-wideband five-bit digital attenuator.A Compact Ku-Band 6-bit Attenuator in 0.35?m SiGe BiCMOS Technology work in the 14~18GHz band which has six different attenuation units,and it achieves an attenuation range of 31.5 dB in a 0.5 dB step size.The emphasis of the 6-bit digital attenuator is reducing the chip area,keeping low additional phase shift and insertion loss while maintaining high precision attenuation.Therefore,the switch embedded structure is chosen to reduce the chip area,the attenuation unit with inductance correction network is used to improve the additional phase shift of the circuit,and the three-well transistor is used to reduce the insertion loss of the whole circuit.The final results show that the insertion loss is 7.4~8.6dB,the additional phase shift is varying from-8°to 8°over 14~18GHz.The chip size of 0.27 mm~2 only excluding testing pads.Compared with the same type of attenuator,it has better performance.The ultra-wideband digital attenuator is designed based on 55nm CMOS process.The bandwidth is DC~70GHz.It has five different attenuation units,and its attenuation range is 0~15.5dB in a 0.5 dB step size,A hybrid structure with a distributed structure and Pi attenuation network with capacitive correction and stacked transistors which makes the attenuator still have good performance in the bandwidth of DC~70GHz.At the end of this thesis,a broadband limiting amplifier based on IBM 0.13?m SiGe BiCMOS process is introduced as an extension.The design adopts three-order interleaved active feedback to enhance bandwidth,output stage uses buffer which can amplify gain and match simultaneously.What's more,The DC feedback loop is added to suppress DC offset.The simulation results show that the gain of the limiting amplifier is 36 dB and the bandwidth is about DC~8GHz.When the signal with voltage swing of 50mV passes through the limiting amplifier,the circuit shapes the signal and amplifies the signal to200mV,and when the signal with voltage swing of 200mV passes through the limiting amplifier,the output signal is still 200mV,thus completing the function of limiting amplitude.