A 400-MHz CMOS radio front-end for ultra low-power medical implantable applications

A 400-MHz ultra low-power radio front-end for medical implantable applications has been implemented in a 0.13-µm CMOS technology. The circuit consists of an up-converter, a down-converter, and a LO frequency synthesizer. The up-converter employs a push-pull PA, which achieves a saturated output power of 0 dBm with a maximum power added efficiency of 32%. Moreover, the up-converter exhibits a −30-dBc ACPR at an output power of −0.5 dBm with a 200 kbit/s GFSK input signal. The down-converter provides excellent linearity performance exhibiting an output compression point of 1.13 Vpp, an IIP3 of −23 dBm, and an IIP2 of 8.7 dBm despite a current consumption as low as 1.5 mA. It has a 45-dB conversion gain and a 7.4-dB noise figure. The LO frequency synthesizer features a fully-integrated LC VCO and programmable channel steps. It provides a phase noise better than −96 dBc/Hz at 100-kHz offset and a spur rejection of −52 dBc. Operating from a 1.2-V supply, the overall front-end draws 3 mA in receive mode and 4.5 mA in transmit mode.