This paper presents a new radio architecture targeting RF transceivers for WSN, WBAN, and biomedical applications. The high miniaturization required by such applications is achieved thanks to the combination of high-Q MEMS devices, such as RF BAW resonators and filters and low frequency silicon resonators, together with a low-power RF IC. This requires a dedicated radio architecture accounting for the advantages and limitations of the MEMS devices. The paper presents such an architecture together with the design of some ultra-low-power and MEMS-specific circuits. The new radio is validated by the demonstration of RX and TX functionalities. The synthesizer, based on a low phase noise BAW DCO and a variable IF LO obtained by fractional division from the RF carrier, achieves a phase noise of - 113 dBc/Hz at 3 MHz. It can intermittently be locked to a low frequency reference (e.g. 32 kHz XTAL or thermally compensated silicon resonator) to correct for the BAW aging and thermal drift thanks to an ADPLL where the lock state can be memorized for nearly immediate settling after returning from an idle period. A sensitivity of - 87 dBm is obtained in receive at 100 kbps for a global power consumption of 6 mA. The transmitter demonstrates a high data rate quasi-direct 1-point modulation capability with the generation of a -4 dBm, 1 Mbps, GFSK signal with an overall current of 20 mA.