Research On Millimeter-Wave Broadband Frequency Multiplier And Harmonic Mixer

With the frequency range of 110 GHz?170 GHz, D-band is one of the atmospheric windows in millimeter wave band. It has a wide application prospect in broadband communication, security inspection and environment monitoring due to the advantage of short wave and high information capacity, which has very important value in both military and civil area. With the rapid development of ultra-high speed and capacity data transmission technology and high resolution imaging technology, it requires a broader working bandwidth in millimeter wave systems. For the D-band down converting module, it is difficult to develop the local oscillators in the corresponding frequency band, harmonic mixers can be an effective solution to this problem. Based on domestic existing technical conditions and the research work of our study group, a E-band full band frequency doubler (can be used as the LO driver of the mixer) and a D-band broad band sub-harmonic mixer are designed and fabricated. A D-band full band bandpass filter with high suppression is developed simultaneously. The main achievements of this dissertation are as follows:1. A E-band full band frequency doubler is designed based on the Schottky barrier diode DBES105a delivered by UMS company. The frequency doubler utilizes the structure of series diodes with more simple and reliable way of welding. Two parallel diodes are connected to the circuit so that the power capacity can be increased. The input and output transition probes, input lowpass filter, DC biased lowpass filter, grounded filter, input and output match circuit are designed and simulated by using HFSS software. Then the integrated EM model which include all the passive parasitic structures and embedding networks of the frequency doubler is built and simulated to obtain the linear frequency response. The nonlinear characteristics can be obtained by combined with the nonlinear parameters of diode junction with the help of ADS software. The frequency doubler is fabricated according to the simulation result. The test result shows that the measured typical conversion loss is 10.5 dB (typical conversion efficiency is 8.9%) and the output power is typically 11 dBm while the peak output power is 13.34 dBm with the input driving power ranges from 20 dBm to 22.7 dBm.2. Based on the research work of our study group, a D-band broadband sub-harmonic mixer is designed. The sub-harmonic mixer utilizes the classic structure of anti-parallel diodes. One of the Schottky junctions is shorted in each diode to reduce the demand for LO signal power. The input transition probes and match circuit for RF and LO signal are designed and simulated by using HFSS software. At the RF port, two stage RF quarter-wavelength matching line is designed as the LO signal recycling network and IF signal ground loop. At the LO port, three stage RF quarter-wavelength matching line is designed as RF signal recycling network. The IF lowpass filter utilizes the improved two stage CMRC structure which has a smaller size and broader stopband compared with the conventional step impedance lowpass filter, effectively improves the isolation between the LO port and IF port. Then by combining with the circuit analyze method and field simulation, the integrated sub-harmonic mixer is simulated and optimized. The sub-harmonic mixer is fabricated according to the simulation result. The test result shows that the measured conversion loss is typically 13 dB within the RF frequency range of 137 GHz?160 GHz. When the E-band frequency doubler is used as the LO driver for the D-band sub-harmonic mixer and the IF frequency is set at 1 GHz, the measured RF bandwidth is about 137 GHz?156 GHz and the typical conversion loss is 12.5 dB.3. By combining with the conventional H-plane inductance diaphragm waveguide filter and symmetrical notch cavity, the suppression of the filter is greatly improved, especially at the frequency close to the passband edge. A D-band full band bandpass filter with sharp rejection is designed by using the high frequency electromagnetic simulation software HFSS. The test result shows that the measured insertion loss is typically 1.2 dB within the filter passband of 110 GHz?170 GHz and the measured suppression is greater than 42 dB at 100GHz and 29 dB at 180 GHz, which verifies the effectiveness of the symmetrical notch cavity.