A Low Phase-Lag Self-Powered SECE Interface Circuit for Pressure-Type Piezoelectric Energy-Harvesting Compatible With COTS Pressure Sensors

The charge-extraction circuits for cantilever-type piezoelectric (PE) vibrational energy-harvesters (EHs) are well established. However, energy-extraction circuits for a transverse-moving diaphragm-type (pressure-type) PE-EH have not yet been thoroughly investigated. Compared to cantilever-type-EH that operates at the resonance frequency of 50–200 Hz, the pressure-type-EH operates at under 2 Hz. This work proposes a new self-powered CMOS synchronous electric charge extraction (CMOS SECE) circuit for pressure-type PE-EH. The proposed circuit uses peak detectors (PDs), which employ precharging and body (back-gate)-drive enhanced PMOS switches. This novel design enables lower switching phase-lag and higher efficiency wasting significantly less power compared to previously reported low phase-lag PDs. The phase lag is reduced by around 50% for a peak voltage close to the startup voltage. The overall harvesting efficiency is 78.04% at the peak voltage (
$V_{\mathrm {PM}}$
) of 3.5 V, which is much higher than other recently reported self-powered CMOS energy extraction circuits. The circuit is fabricated using the 180-nm TSMC CMOS technology and consumes 0.4-mm two active area. The proposed circuit can extract charge from any commercial-off-the-shelf (COTS) PE pressure-sensor when the sensor is in the idle mode, enabling an extra add-on feature for the piezoelectric pressure sensors.