External Capacitor-Less Low Drop-Out Regulator with 25 dB Superior Power Supply Rejection in the 0.44 MHz Range
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This paper presents design techniques for a high power supply rejection (PSR) low drop-out (LDO) regulator. A bulky external capacitor is avoided to make the LDO suitable for system-on-chip (SoC) applications while maintaining the capability to reduce high-frequency supply noise. The paths of the power supply noise to the LDO output are analyzed, and a power supply noise cancellation circuit is developed. The PSR performance is improved by using a replica circuit that tracks the main supply noise under process-voltage- temperature variations and all operating conditions. The effectiveness of the PSR enhancement technique is experimentally verified with an LDO that was fabricated in a 0.18 m CMOS technology with a power supply of 1.8 V. The active core chip area is 0.14 mm, and the entire proposed LDO consumes 80 A of quiescent current during operation mode and 55 A of quiescent current in standby mode. It has a drop-out voltage of 200 mV when delivering 50 mA to the load. The measured PSR is better than-56 dB up to 4 MHz when delivering a current of 50 mA. Compared to a conventional uncompensated LDO, the proposed architecture presents a PSR improvement of 34 dB and 25 dB at 1 MHz and 4 MHz, respectively. 2014 IEEE.