A Subharmonic Image Rejection Mixer Using a Single Anti-parallel Diode Pair

This paper presents a simple method to design a subharmonic image rejection mixer in microstrip line technology. The impedance matching unit for the diode is used to reject the image frequency thereby reducing cost and implementation area of the mixer. As an example, a subharmonic mixer (×2) is designed using a single anti-parallel Schottky barrier diode. The mixer down-converts the RF frequency of 10 GHz to 1 GHz and provides measured isolation of 24 dB at the image frequency of 8 GHz. The measured conversion loss is 8 dB at 10 GHz for an optimum LO power of 7.6 dBm with measured IP
_1dB
of 0 dBm. The proposed method can be easily followed at millimeter-wave frequencies.