An ultra-low power multi-rate FSK transmitter for wireless sensors and biomedical applications

An ultra-low power multi-rate FSK transmitter implemented in 0.18 μm CMOS process is presented. A digital frequency interpolator is adopted in the transmitter for achieving multiple data rate transmission. Power consumption of the transmitter is dependent on the required transmitted data rate. Thus, high power efficiency can be achieved. As applying for implantable or wearable biomedical devices, the feature of high power efficiency leads to a great improvement of lift time of the implantable or wearable biomedical devices. Moreover, all transistors of the transmitter are operated under sub-threshold region for realizing ultra-low power consumption. The transmitter consumes 378 μW to 424 μW according to the transmitted data rate varying from 200 kb/s to 2 Mb/s under a supply voltage of 0.7 V. Therefore, minimum energy consumption per transmitted bit of 212 pJ/bit can be achieved under the maximum transmitted data rate of 2 Mb/s.