Ultra-Wideband Double Balanced Mixer Utilizing A Compact Planar Balun

摘要

A new double balanced mixer (DBM) operating from 3.1 to 10.6 GHz utilizes a compact planar balun. To meet the requirements for ultra-wideband operation and improve return loss, a T-junction formed by side coupled slotlines (SCSL) and microstrip with a wideband microstrip to SCSL transition is employed. The balun's balanced ports are in the form of adjacent microstrip lines located on the same side as the double balanced mixer. This is a practical advantage because it eliminates the crossing of the transmission lines making it more suitable for MIC design. The mixer exhibits a conversion loss of less than 13 dB from DC to 100 MHz IF. Port-to-port isolation is better than 25 dB over the RF and LO bandwidths of 3.1 to 10.6 GHz.