Two-step channel selection-a novel technique for reconfigurable multistandard transceiver front-ends

This paper starts with a review of the prevailing channel-selection techniques utilized so far in the design of wireless transceiver analog frontends before describing a novel two-step channel-selection technique, which handles the traditionally unwanted image, in radio frequency-tointermediate frequency (RF-to-IF) or IF-to-RF frequency conversion, as a useful adjacent channel of the desired one, and selects deliberately either of them from IF to baseband (or baseband to IF). Thus, one more channelselection possibility is created for both low-IF receivers and two-step-up transmitters. The consequential benefits of introducing channel selection at IF consist of two. First, many design specifications (such as phase noise and settling time) of the RF frequency synthesizer and local oscillator can be substantially relaxed. Second, a low-IF/zero-IF reconfigurable receiver and a direct-up/two-step-up reconfigurable transmitter can be synthesized to match better with narrowband-wideband-mixed multistandard systems. The operating principles of such architectures are presented in easy-tounderstand complex-signal spectral-flow illustrations, and their practicability is demonstrated in the design of a Bluetooth/IEEE 802.11FH/HomeRF multistandard receiver. SPECTRE simulation results validate the reconfigurable functionalities mainly implemented by a triplemode channel-select filter and a multifunctional sampling-mixer scheme.