Low noise μWatt interface circuits for wireless implantable real-time digital blood pressure monitoring

A wireless implantable blood pressure monitoring microsystem employs an MEMS capacitive pressure sensor, which converts pressure signal to a capacitance change with a sensitivity of approximately 0.7 fF/mmHg. Low-noise muWatt correlated-double-sampling capacitance-to-voltage interface converter followed by an 11-bit cyclic ADC further converts the capacitive signal to a digital output for data processing and telemetry. The prototype microsystem achieves a resolution of 0.1 mmHg over a 1 kHz bandwidth with a dynamic range of 59 dB and consumes 18 muA from a 2 V supply.