Remote calibration of wireless power harvest

A calibration technique to maximize the power harvest of passive wireless microsystems is proposed. We show that both the impedance and resonant frequency of the transformer matching network are sensitive to process spread and load variation, and can be calibrated by tuning a shunt varactor at the secondary winding of the transformer to maximize power transfer from the antenna to the transformer and power efficiency of the voltage multiplier. An ultra-low power current tuning technique and a maximum peak amplitude detection technique to automatically allocate the optimal tuning capacitance at which maximum power harvest exists. The proposed transformer matching network is designed in IBM CMRF8SF 130 nm 1.2 V CMOS technology and its effectiveness is validated using post-layout simulation.