Design of Low Conversion-loss High Order Sub-harmonic Mixers with CMRC

Abstract

Mixer is widely used in wireless communication system, it can acts as modulator and demodulator. So, a good performance mixer is desired. In this project, a fourth order sub-harmonic mixer is proposed. It not only provides a good isolation between the two inputs and an output port, but also greatly reduces the cost of the local oscillator. By using this 4th order subharmonic mixer in this project, the frequency of the local os-cillator can be reduced by four times in order to demodulate the same received signal’s frequency. However, the conversion loss of the sub-harmonic mixer is usually as high as 10-18dB in the market. Therefore, three CMRCs (compact microstrip resonant cell) are incorporated to minimize the loss and size in this project. At 3GHz, the simulated conversion loss is reduced to 7.1dB. Even though the experimental loss increases to 10.0dB, it is proved that poor fabrication and unbalanced diode connection are the sources of the deviation. Therefore, the designed fourth order sub-harmonic mixer with CMRCs provides a low-cost and high-performance solution to microwave application.