A self-regulated voltage/current-mode integrated power management with seamless mode transition and extended input-voltage range

摘要

An integrated power management (IPM) structure for inductive power delivery is presented with the capabilities of seamless transition between voltage and current mode operations, extended input-voltage range, self-regulation, and over-voltage protection (OVP) with only one off-chip capacitor. Unlike conventional IPMs, which discretely operate in either voltage mode (VM) or current mode (CM) for a limited range of the input voltage (i.e., with dead zone), the proposed IPM continuously employs both VM and CM and eliminates the input-range dead zone. The receiver (Rx) LC-tank is repeatedly shorted for several power carrier cycles to form a high-Q parallel Rx LC-tank and store energy. If the AC voltage across the Rx coil (V_p) surpasses the DC load voltage (V_l), the load capacitor (C_l) is automatically charged through an efficient half-wave rectifier operating in VM. Otherwise for V_p<; V_l, at the end of each switching cycle the Rx resonance capacitor is opened at the time zero-crossing of V_p, when the maximum energy is stored in the Rx coil, to transfer the stored energy to C_lvia CM operation. For self-regulation and OVP, reverse current from CL to the Rx LC-tank is employed. A proof-of-concept IPM was fabricated in a 0.35 μm 2P4M standard CMOS technology. In measurements, the IPM operated at 1 MHz and achieved a self-regulated V_lof 3 V for a wide range of V_pwith OVP by switching the Rx LC-tank at its optimal frequency of 142 kHz and frequently employing reverse currents.