±3% voltage variation and 95% efficiency 28nm constant on-time controlled step-down switching regulator directly supplying to Wi-Fi systems

For high efficiency, the proposed constant on-time controlled switching regulator (SWR) directly supplies to Wi-Fi systems without cascading any low dropout regulators. On-time value adjusted by the proposed transient-enhanced technique greatly reduces transient voltage variations. Besides, an asynchronous auto-zero technique is used to minimize offset voltage effect to ±0.5% in steady state. Experimental results show voltage variation is smaller than ±3% and peak efficiency is 95% with a small silicon area of 0.0019 mm², which is only one-twentieth of conventional design. The proposed well-regulated SWR can improve error vector magnitude (EVM) from -27.2 dB to -33.6 dB.