Implementing I/Q Single Sideband and Image Reject Mixers

摘要

In "An Introduction to Passive I/Q, Single Sideband and Image Reject Mixers," published in the December 2015 issue of Microwave Journal, we highlighted the difficulty in maintaining high performance over a broad bandwidth in these special mixers. High performance requires precise amplitude and phase balance over the bandwidth of operation. Any imperfection in the phase balance of the LO or the amplitude or phase balance of the I/Q channels will lead to imperfect sideband cancellation in a single sideband (SSB) or image reject (IR) mixer or imperfect rejection of the unwanted channel in an I/Q mixer. Maintaining this balance is the subject of ongoing research and development. In this article, we review the state-of-the-art in quadrature phase shift generation. We will also discuss techniques to compensate for inevitable imperfections in quadrature signal generation and combination.