Nano–power‐integrated precision rectifiers for implantable medical devices

Abstract

SummaryTwo ultralow power CMOS full‐wave precision rectifiers aimed at analog signal processing in implantable medical devices are presented. The rectifiers require no diodes and utilize a single or two transconductors (operational transconductance amplifier [OTA]) as the active element, to reduce power consumption to a minimum. First, a voltage‐to‐current rectifier consuming only a 120‐nA supply current is presented and later is used to estimate the average AC amplitude of a piezoelectric accelerometer output (0.5–15‐Hz bandwidth) in an adaptive pacemaker. This rectifier is based on a linearized transconductor and a comparator to toggle the output current sign. Then, a novel voltage rectifier consuming less than 10 nA is presented based on a single nanopower OTA and a pass transistor and later is utilized in a pacemaker's cardiac sensing channel (60–200‐Hz bandwidth) circuit, incorporating the rectifier to detect positive and negative voltage signal spikes. Both rectifiers were designed in a 0.6‐μm CMOS technology, fabricated, and tested, and the measurement results closely fit the expected performance.