A highly linear short-wave broadband double-balanced mixer

Abstract

A short-wave broadband mixer with high linearity based on double-balanced structure is presented. The mixer is realized by double-balanced passive COMS FET array and balun technology. The channel-width and the bias-voltage of the FET are adjusted to optimize the mixer's performance. The balun is implemented by radio frequency ferrite transmission line transformer that has low insertion loss over wide bandwidth. The radio frequency (RF) frequency is 1.5~30MHz, the local oscillator frequency (LO) is 71.5~100MHz and the intermediate frequency (IF) is 70MHz. The test results show that the conversion loss is about 6.5 dB, the referred 1-dB compression point (P1dB) is above 12dBm, the LO-IF isolation is above 65dB, the LO-RF isolation is above 70dB and the third order input intercept point (IIP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) is above 45dBm.