A wideband mixer designed with low conversion loss through the entire W-band

In this paper, a mixer is designed with low conversion loss through the entire W-band. A novel low pass filter is proposed and used to select the intermediate frequency signal with large rejection of the local oscillator (LO) and radio frequency (RF) signals. A single slot is added on the LO passage to achieve impedance matching in a narrow frequency band, while two slots and one metal strip are added on the RF passage to achieve impedance matching in a wide frequency band. The detailed design process is presented, where a more accurate full-wave simulation model of the adopted diode is suggested. Difference in performances can be obtained by changing the key sizes of the matching structures. One sample is fabricated, and the measured conversion loss is less than 9.5dB through the entire W-band (from 75 to 110GHz) under fixed LO condition. The measured return loss of RF port is between 5 and 13.5dB.