A 280-MHz CMOS intra-symbol intermittent RF front end for adaptive power reduction of wireless receivers

For adaptive reduction of power consumed by wireless receivers, we developed the first intra-symbol intermittent (ISI) RF front-end with 0.35-μm CMOS technology. In the demodulation mechanism, the RF output of the LNA is down-converted to an IF by the mixer, and the LNA and mixer operate synchronously and intermittently within a single symbol-length. Because the ISI frequency is low and the impedance-matching condition is maintained, the demodulation can be performed with low power. We experimentally demonstrate that demodulation (BPSK: 9.6 kbps) can be achieved with no intermodulation, where the intermittent operations ratio (IOR) is 12%. This ISI operation of the RF front end is enabled by a newly devised fast-transition LNA and mixer. A theoretical analysis of thermal-noise aliasing in the RF ISI circuit reveals that RF ISI operation is more useful for the adaptive power reduction than current control (CC) in an RF front-end with continuous operation and that when the IOR is about 10%, RF ISI operation is most effective and the NF is 1.2 dB lower than with RF CC.