Resesrch And Applications On Key Technology For Microwave Millimeter Wave Receiver

With the rapid growth of wireless communication and radar system,microwave spectrum resources in low frequency band are becoming more and more crowded,electronic systems are developing towards millimeter-wave band with higher frequency and broader frequency band,and the related receiver front-end theory and key technologies have become the current research hotspot.The objective of this work is to develop high-performance millimeter-wave receiver,and the technical problems existing in the current microwave millimeter-wave receiving system are deeply studied,including the unbalance of amplitude and phase in ultra-wideband I-Q mixing circuit,the suppression of spurious signals with high rejection ratio,the anti-strong interference characteristics of the system and the realization of large adjustable gain range.At the same time,a high-performance local oscillator train in W-band down converter is developed.The performance of the receiver system is tested.The main research progress of this paper includes the following three aspects:1.Research on key technologies in ultra-wideband high performance I-Q mixers.Aiming at solving the problem of I-Q mixing amplitude and phase balance of multi-octave output,a multi-octave amplitude and phase adjusting circuit is designed,which achieves the excellent characteristics of I-Q two-way amplitude imbalance less than 0.3dB and phase orthogonality error less than 2 degrees in the 18-octave range.In order to effectively improve the spur suppression of I-Q mixing circuit,a solution of multi-zero low-pass filter is proposed,which achieves the suppression effect of in-band and out-band spur suppression greater than 50 dBc.In order to overcome the blocking problem of receiver caused by leakage of transmitting strong interference signal,a third-order DC blocking circuit is designed,which makes the rejection of strong interference signal below 100 KHz in baseband signal more than 30 dBc,and effectively improves the ability of receiver to resist strong interference signal.To expend the receiver's dynamic range,a six-digit numerically controlled attenuator is applied to control the gain of the overall receiving circuit.An adjustable gain range of 40 dB is achieved with an LSB of 1dB.2.Development of high performance local oscillator in W-band down converter.The local oscillator link consists of filter amplifier circuit,up-conversion circuit and frequency doubling circuit.The spurious and phase noise of the local oscillator signal of the W-band down converter will directly influence the quality of the output signal of the receiver.In view of the problem of coherent signal suppression in W-band local oscillator link,the interference of phase-locked source coherent signal is fully considered in the LO scheme design.In the filter circuit,a novel high-band-out suppression band-pass filter is proposed,which improves the out-of-band rejection by 10 dBc compared with the traditional card-issuing filter,effectively suppresses the coherent signal interference existing in the local oscillator signal,and improves the local oscillator chain.In the up-conversion circuit and the multiplier circuit,a corresponding band-pass filter is also specially designed to suppress unwanted harmonic components.The C-band local oscillator signal is multiplied to the W-band as the local oscillator input for the W-band down-conversion.The designed high performance local oscillator link guarantees the spurious performance of the W downconverter output signal.3.W-band receiver performance test.A complete W-band receiver system measurement scheme was designed,and the performance indicators such as receiver system gain and saturated output power are tested.The test results show that the noise figure of the W down converter is 9.55 dB,the gain of the whole machine is greater than 50 dB in the working frequency band,the noise figure of the whole machine is 12.22 dB,the dynamic range of the receiver is 40 dB,and the receiver channel saturation output power is 8dBm.The external spurious suppression is greater than 50 dBc.All the indexes of the products are meet the requirements.