In this dissertation, a study on high-efficient dual-mode active rectifier for wireless power receiver and dc-dc converter is proposed. The main object of the research is to improve the power conversion efficiency of the system. The Dual mode is proposed based on Alliance for Wireless Power (A4WP), Wireless power consortium (WPC). An adaptive alignment gate controller technique is proposed in this dual-mode active rectifier to block the reverse leakage current and improve the power conversion efficiency (PCE). To improve the efficiency of the rectifier, the proposed charge recycling approach is used after the high side gate driver so that the current produced by the gate driver switching can be recycled and applied to the rectifier output voltage (VRECT) to improve the rectifier's PCE and a step-down dc-dc converter with a proposed bootstrap circuit and dynamic pull-up resistor gate driver circuit is designed.

In this thesis, an electromagnetic (EM) rectifier circuit is proposed. The proposed circuit is composed of two stages. In the first stage electromagnetic (EM) rectifier uses an improved rectifier structure with active diodes powered internally by a passive ac-dc positive and negative voltage quadrupler. The second stage is step up dc-dc converter with proposed soft start circuit and min-max duty generator circuit. The system uses an active diode rectifier circuit and is powered by a passive ac-dc quadrupler circuit. The active diode architecture minimizes voltage drop and is more suitable for generating high load currents than passive diode-connected structure. An unbalance comparator circuit and CMOS switch used in EM rectifier make up the active diode structure.

A dual-mode rectifier along with step-up dc-dc converter is fabricated with a 0.18 μm bipolar-CMOS double-diffused metal-oxide-semiconductor process (DMOS). The total die area including the pad is 2.64 mm x 2.6 mm. The measurement results show that the active rectifier achieves peak power conversion efficiency (PCE) of 94.7% and generates an output voltage of 7.68 V in WPC mode and 9.1 V with 93.4% efficiency in A4WPC mode. The input voltage varies from 10 VP-P ~ 12 VP-P. Similarly, the step-down dc-dc converter obtains a peak PCE of 93.2% at a load current of 500 mA while producing an output voltage of 5 V. The overall system efficiency at A4WP and WPC mode are 86.7% and 88.2%, respectively. The EM rectifier along with step-up dc-dc converter is fabricated in a 130nm CMOS technology. The input voltage of dc-dc is the output voltage of EM rectifier, which is 1V and output voltage is 1.3V at 0.5mA load current. The efficiency of EM rectifier is 95.6% at 0.6 mA load current and step-up dc-dc converter is 94.2%, system efficiency is 90% at 10 Hz frequency.