Research On Key Technology Of W-band Broadband Transceiver Front End

Compared with traditional narrow-band radar,broadband radar has superior anti-interference and anti-multipath capability,high range resolution and target recognition capability,and has been widely used in the fields of detection and imaging.The millimeter wave broadband transceiver front-end is the key component of the broadband radar signal generation and transmit-receive,and its performance directly affects the performance of the entire radar system.This paper introduces the design process of a W-band broadband transceiver front-end whose signal form is stepped frequency.Firstly,the architecture of millimeter wave transceiver and the theory of stepped frequency radar are expounded.Then the subject indicators is given and the system overall design blue print of the transceiver front-end is proposed according to the indicators.The whole transceiver front-end is divided into five modules: stepped frequency source module,microwave source module,millimeter wave transmitting module,millimeter wave receiving module and intermediate frequency demodulation module,then the design and implementation of five modules are separately introduced in detail from the perspectives of index consideration,chip selection,circuit design and module implementation.The transmission link of the W-band broadband transceiver front-end adopts the main-vibration amplification architecture,and the transmission signal frequency ranges from 87 GHz to 97 GHz,and the frequency step value is 100 MHz.The receiving link adopts a secondary down-conversion super-heterodyne receiver architecture,the first local oscillator signal has a frequency range of 84.6 GHz to 94.6 GHz,the frequency step value is 100 MHz,and the antenna received signal is mixed to an intermediate frequency of 2.4 GHz with the first local oscillator signal.The intermediate frequency signal is filtered and amplified,and sent to the intermediate frequency demodulation module,then the signal is directly mixed with the second local oscillator signal of 2.1 GHz to obtain a baseband demodulation signal of 300 MHz or IQ mixed with the second local oscillator signal of 2.4 GHz to obtain a zero frequency baseband demodulation signal,the demodulation signal is ultimately used for baseband signal processing.All the indicators meet the requirements in theory,and finally the system key indicators and demodulation functions are tested.The test result show that phase noise of the X-band transmit excitation signal before eight times of frequency multiplication is better than-95dBc/Hz@1kHz,-90dBc/Hz@10kHz,-103dBc/Hz@100kHz and-124dBc/Hz@1MHz,the spurious suppression is above 60 dBc,and the W-band transmit signal power is greater than 26mW(+14dBm),and the power flatness is within 2dB.Meanwhile the 300 MHz baseband demodulation function and zero frequency baseband demodulation function can work normally in imaging applications.Domestic research on W-band stepped frequency broadband radar is very lacking,the transceiver front-end developed in this paper provides an idea for this type of radar RF front-end design.