A 2.4-GHz MEMS-based PLL-free multi-channel receiver with channel filtering at RF

A low power 2.4-GHz receiver exploiting the intrinsic high quality factor (Q) of Bulk Acoustic Wave (BAW) resonators is presented. A novel way of performing simple integer division of the BAW digitally controlled oscillator (DCO) signal to address multi-channels and thus making the receiver become PLL-free is proposed in this paper. To the best of our knowledge, this work is the first one to report a multi-channel (arbitrary frequency) receiver whose frequency synthesis depends solely on the low phase noise BAW DCO and does not include a PLL. A pseudo-lattice made of BAW resonators and capacitors is used in the channel selection filter at RF. The filter provides both bandwidth and frequency tuning by Q-enhancement of the pseudo-lattice and capacitor switching respectively. The RF front-end involves both conventional and sub-sampling based down-conversion. The receiver is integrated in 0.18-μm CMOS process. The channel filter is tuned to provide 1-MHz bandwidth and the front-end provides 46.2-dB of conversion gain with 48.5-dB rejection at 15-MHz offset from the center frequency. The receiver consumes 5.94-mA from a 1.8-V power supply.