Study On Sub-harmonic Mixing Techniques For Millimeter Wave SSB Receiver

For a high frequency especially a millimeter-wave communication system, single side-band(SSB) receiver can not only save transmitting power, but save the spectrum resources. Furthermore, developing an oscillator that has both high frequency and stable performance remains a great challenge. One of ways to develop a high performance system is to use sub-harmonic mixer. Therefore, it is significant to study the SSB receiving scheme based on sub harmonic mixing.This thesis introduces the domestic and international developments of the SSB receiver in recent years. It focuses on sub-harmonic mixing with simple circuit topology to achieve the SSB reception at millimeter-wave band. Specifically, it is based on the second sub-harmonic mixing in SSB receiver, and further studied on the fourth sub-harmonic mixing to achieve SSB reception at millimeter-wave band. The ultimate goal is to realize the SSB receiver with low conversion-loss and high image-rejection by using simple circuit topologies.In this thesis, a second sub-harmonic image rejection mixer and a fourth sub-harmonic image rejection mixer are designed. Each of the proposed mixers respectively consists of two harmonic mixer units, a dual-band coupler, and an IF(intermediate frequency) coupler. Diodes with anti-parallel pair are used in the studied mixers. Functions of two dual-band couplers are to achieve the same power and quadrature phase at RF(radio frequency) and LO(local oscillation). In order to make the whole mixer circuit compact, combining the lumped capacitors and the geometric fractal is adopted for the IF coupler.Simulations show that the lowest conversion-loss of the second sub-harmonic image rejection mixer is about 7.5 dB after optimization, while the image rejection is better than 20 dB. The measured results show that the best conversion-loss is 8.1 dB, and the image rejection ratio is better than 20 dB under a LO power of 7.5dBm, and the isolation is better than 15 dB. The simulation result of the lowest conversion-loss of the fourth sub-harmonic image rejection mixer is 9.5 dB, and the image rejection ratio is better than 20 dB under a LO power of 13.5dBm, and the isolation is better than 14 dB.