A dual-band subharmonic mixer with high RF-IF isolation

In this paper, a dual-band subharmonic mixer (SHM) is proposed. Two radio frequencies (RF) are down converted to the desired intermediate frequency (IF) by using the second and fourth harmonics of the local oscillator (LO) frequency. A dual-band RF blocking section has been designed and is integrated with the IF branch to minimize the leakage of RF power to the IF port. Thus, a high value of RF isolation to the IF port and hence lower conversion loss is achieved. A prototype has been designed for RFs 2.4 GHz and 5GHz with the IF of 200 MHz. Measurements show that for a LO power of 4dBm, the conversion loss is 11.14 dB and 12.72dB at 2.4 GHz and 5GHz, respectively. In addition, both of the RFs are suppressed at least by 30 dB at the IF port.