A novel microstrip mixer using complex coupler and high-performance low-pass filter

A novel microstrip mixer is proposed in this paper by using inherent complex impedance-matching coupler and highperformance low-pass filter. Based on accurate complex terminated impedances and analytical design method, the designed coupler can directly match the complex load impedances to the desired real source impedance 50 Ohm. Due to coupled-line circuit, the used low-pass filter has advantages of small size and wide up stop band. The designed mixer operates at 2 GHz. The measured conversion loss is about 8.5 dB when the 2-GHz 2-dBm Local Oscillator (LO) and 2.3-GHz-20-dBm Radio Frequency (RF) are inputted. This proposed mixer features compact size and high linearity performance.