A 2.4-GHz MEMS-Based PLL-Free Multi-Channel Receiver With Channel Filtering at RF

A Bulk Acoustic Wave (BAW) resonator based 2.4-GHz low power receiver is presented in this work. The intrinsic high quality factor (
Q
) of the BAW resonator (around 400 at 2.4-GHz) is exploited to provide channel selection at RF and in the frequency synthesis. A novel way of addressing multiple channels (arbitrary frequency) using integer dividers and a BAW digitally controlled oscillator (DCO) and thus avoiding the need for a PLL is proposed in this work. 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 BAW pseudo-lattice with frequency and bandwidth tuning is proposed which significantly improves the rejection of unwanted signals in the channel filter. A quadrature sub-sampling mixer is used to down-convert the selected channel to baseband. The receiver is designed and integrated in a 0.18- μm CMOS process. With
Q
-boosting, the channel filter provides bandwidth down-to 1-MHz. For a BFSK modulated signal, the receiver exhibits a sensitivity of -78 \mathchar "702
D
dBm at a rate of 268-kbps for a BER of 10
^-3
. The total power consumption of the receiver is 5.94-mA from a 1.8-V power supply.