A 24GHz sub-harmonically image rejection mixer with various asymmetrical diode pair

In this work, we compare three different mixing anti-parallel diode pair (APDP) which is EE/ED/DD mode for single side-band sub-harmonically image rejection up converter mixer (SHIRM), we analysis the APDP effect about Image Rejection Ratio (IRR) and Conversion Loss(CL). This structure is a 24G SHIRM using reentrant couplers for radio frequency (RF) and the quarter-wavelength line for local frequency (LO). The SHIRM is realized size employing four anti-parallel diode pairs for mixing frequency, fabricated in a 0.5-μm GaAs process. And the proposed circuit with a symmetric layout provides good matches on amplitude and phase performances. The measured results exhibit a minimum conversion loss of 16.25 dB for DD mode, a maximum image rejection ratio of 20.4 dB for EE mode finally all port's isolation better than 10 dB. The chip area is very compact, only 1 × 1 mm 2 .