A Low-Voltage and LDO-Less Wireless Pressure Sensor Readout System with Current Mode Pseudo PLL and Charge Pump Powered UWB Data Transmission for Implantable Health Monitoring

This paper presents an implantable pressure sensor readout system (IPRO) which can work at low voltage and does not need internal low dropout regulator (LDO). This paper has made a series of optimizations for power consumption. The power supply part of the IPRO uses 434 MHz energy harvesting (EH), and the corresponding ultra-low power undervoltage lockout (UVLO) circuit is used. The analog front-end (AFE) and signal processing parts use current mode and differential pseudo phase locked loop (DPPLL), which can work stably under low voltage and maintain a certain degree of accuracy and power rejection ability. The wireless data transmission part adopts the impulse ultra-wide band (IR-UWB) scheme. Its ultra-low power consumption allows it to be powered by a charge pump. In order to further optimize power consumption, a simplest encoding circuit suitable for the front-end output form was proposed, and a power oscillator (PO) with accelerated starup was used to optimize area and power consumption. The system is implemented in 180 nm Complementary Metal Oxide Semiconductor (CMOS) process, with a chip area of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.1 ^*1.0$</tex> mm”, The measurement results indicate that the typical working voltage of the IPRO is 0.8 V, the typical power consumption is 11.8 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{W}$</tex>, and the accuracy is 1.11 mmHg. Compared with existing designs, there is a significant optimization in supply voltage and power consumption.