Ka-band High-speed Pulse Detector

In this thesis, firstly, based on the theories of pulse transmission and millimeter wave detector, we carefully analyzed the recent work with regard to millimeter wave detectors. Secondly, the structure of the detector is redesigned and the cavity detector topology is chosen for the final design. The figure of merit of this structure is that there is no more need a lowpass filter at the output of the detector, the demodulated video signal can conveniently be fetched out by coaxial cable. Thirdly, although the waveguide structure without transition circuits causes some mismatch problems, it can significantly simplify the circuit complexity. The silicon detector diode manufactured by Ya Guang Semiconductor Corporation is selected as the core device. The experiment results demonstrate that the response time of the Ka-band detector is less than 300ps, the pulse width is 400ps and the bandwidth of the detector is 3GHz(35~38GHz).The response time of the commonly used millimeter wave pulsed modulation signal generator cannot achieves sub-nano second, as a result of that, it does not meet the requirements of experiment, therefore high speed modulators are needed to be designed, this kind of modulator is used to pulse modulate a continuous millimeter wave signal and then obtain a high speed pulsed millimeter wave signal. In order to verify and compare the experiment results, two kinds of different millimeter wave high speed pulse modulator have been designed, the one is the fin-line structure, and the other is cavity structure.According to the principle of semiconductor devices and the requirements of this project, this thesis has chosen fast response time and very short reverse recovery time Schottky diodes as switch devices. The design procedure of the millimeter wave modulator is as follows: for the first step, the finline to waveguide transition is design in HFSS, and then a HFSS and ADS co-simulation method is adopted to optimize the bias circuits of modulator .The design method of cavity modulator is similar to the cavity detector. The test results indicate that the bandwidth of the finline modulators are narrower than the cavity ones, however, the cavity modulator fulfill every requirement of the project. This research work is focused on the millimeter wave high speed pulse detector as well as the millimeter wave high speed pulse signal detection technology, and this work will find significantly applications in high speed millimeter wave detection technology.