RF mixers are at the core of any communications circuit. Mixers allow the translation of baseband voice and data signals to high frequencies. These frequencies cover the entire electromagnetics spectrum from the hundreds of kHz range (AM radio in the USA) to tens of GHz (radar, military communications, and cellular backhaul). Just like any other analog component, mixers have noise, distortion, and frequency range issues. Note that for the purpose of these slides, Analog Devices will be using down-converting mixers as an example. Down-converting mixers take signals from the RF spectrum and convert them either to a lower frequency range (called an intermediate, or IF band), or convert them all the way down to baseband (DC centered). The math for an up-converting mixer is nearly identical, and all the lessons learned in these slides can be applied to up-converting mixers. One particular effect of the down-converting mixer that users will study in these slides is that a single mixer will actually frequency translate two bands to the lower IF or DC band. The signal which is desired to mix down is in one band, while the other band will contain noise and may contain other spurious components which may degrade the signal. The purpose of these slides is to show how two mixers can be used, in what Analog Devices calls an image reject topology, to greatly suppress the undesired mixing product.