A dual-band subharmonic mixer that employs both the second and fourth harmonics of a local oscillator signal in the mixing process is demonstrated for WIFI application. The design results in a simple and cost-effective mixer as it requires only one local oscillator (LO). A quarter-wave stepped impedance stub has been used to suppress both bands of radio frequency (RF) signal. The proposed dual-band subharmonic mixer is designed for two RF bands with the center frequencies at 2.45 GHz and 5 GHz using a single LO frequency at 1.3 GHz. For mixing purpose, the second and fourth harmonics of LO are utilized. Experimental measurements show high port-to-port isolation and achieve minimum conversion losses of 6.87 dB and 10.0 dB at 2.59 GHz and 5 GHz, respectively. The 3-dB RF bandwidth is 2.3 to 2.95 GHz for the second harmonic and 4.8 to 5.5 GHz for the fourth harmonic of LO signal. The input P1-dB compression points for two modes of the mixer are -9 dBm and -5 dBm, respectively. The RF-to-IF isolations are more than 18 dB (maximum 36 dB) and 20 dB (maximum 33 dB), over both the RF bands.
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