Automated design of a 13.56 MHz corner-robust efficient differential drive rectifier for 10 μA load

A portable automated design methodology using a gradient algorithm and foundry models is presented to optimize the cross-coupled and differential-drive rectifier architectures. The impact of threshold voltage, transistor sizing and capacitance are discussed based on the method results and an RC-filter model. Corner robustness is obtained by applying the proposed method in each corner and choosing an intermediate design that maximizes power conversion efficiency over all corners. An 8-stage corner-resistant rectifier is designed at 13.56 MHz for a 1 Vpp sinusoidal input and a 10 μA load current in 250 nm CMOS bulk technology. The simulated output voltage is 2-2.9 V DC with a 50-70% power conversion efficiency providing a 2029 μW output power. This ultra low power and high efficiency AC/DC power converter can be used in inductive RF links as energy harvester to power implantable or wearable biomedical devices in body sensor networks.