A Single-Stage Bipolar-Output Regulating Rectifier With Negligible Cross-Regulation for Wireless Display

This article presents a 6.78-MHz single-stage bipolar-output regulating (SSBOR) rectifier with symmetrical structure for active-matrix organic light-emitting diode (AMOLED) displays. The proposed full-wave rectifier converts ac power to positive and negative dc voltages through six on-chip switches. To handle high voltage stress, four power switches are stacked MOS as full-bridge rectifying transistors, while two single-NMOS switches are connected between the ac nodes and ground, providing paths for unequal load currents with low conduction loss. This high-integration structure improves power conversion efficiency and reduces chip area. Besides, since the ac current in the series-resonant LC tank varies little with different output loads, there would be negligible cross-regulation during transient response. Two independent pulsewidth modulation (PWM) and type-II compensation circuits work in each output feedback loop. Fabricated in 180-nm BCD process, using only 5-V devices, this proposed rectifier obtains <tex-math notation="LaTeX">$+$</tex-math> 5-and <tex-math notation="LaTeX">$-$</tex-math> 5-V bipolar outputs with a maximum of 500-mA output current each. The measurement results show 86.4% peak power conversion efficiency, less than 15- <tex-math notation="LaTeX">μ</tex-math> s transient recovery time and 103-mV overshoot/undershoot with 50–400-mA load steps, and unnoticeable cross-regulation.