A Single Balanced Mixer Using Compact Branch Line Balun for Ultra-Wideband Applications

This paper presents a single balanced mixer for ultra-wideband (UWB) applications. The proposed mixer utilized a compact branch line coupler as a balun to enhance the overall performance over a wider bandwidth. The mixer design operated with a Local Oscillator (LO) power level of 10 dBm and Intermediate Frequency (IF) of 100 MHz with the balun characteristic of 90° phase shift over UWB frequency. The well-balanced wideband performance of branch line balun matched to diodes results in the enhancement of the conversion loss and isolation. The simulated and measured results of the proposed mixer exhibit conversion loss of less than 19 dB and a port-to-port isolation of greater than 55 dB over a UWB frequency range of 3.1-10.6 GHz.