Toward an Energy-Efficient Bridge-to-Digital Intracranial Pressure Sensing Interface

This work presents an integrated solution for lowering the power consumption in interface circuits for bridge sensors, which consume power because of their low resistances particularly in implantable microsystems, such as intracranial pressure (ICP) monitoring application. The proposed direct bridge-to-digital interface uses a pseudo-pseudo differential (PPD) structure, in which the converter not only provides key benefits of traditional fully-differential interface circuits but also can reduce their complexity with single-ended architecture. It occupies 0.0667 mm2in 0.35-μm standard CMOS technology, where the interface provides 9.13 effective number of bits (ENOB), while cutting the power consumption of a 3 kΩWheatstone bridge down to 363 µW at 1.8 V supply, and sampling rate of 3.72 kHz in post-layout simulations.