Enhanced active feedback technique with dynamic compensation for low-dropout voltage regulator
Analog Integrated Circuits and Signal Processing
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A capacitor-free LDO regulator with the minimized-Q (MQ) and adaptive zero compensation (AZC) techniques is proposed in this paper. With the MQ technique, light load efficiency is greatly improved since only 50µA minimized load current is required. Furthermore, due to noise cancellation from power supply, the LDO regulator with the MQ technique has higher PSR bandwidth with compatible compensation capacitors compared to the Q-reduction technique [1]. Besides, fast transient response time is also achieved because phase margin equals to 60 degree is always maintained by the MQ and AZC techniques. The capacitor-free LDO regulator with the MQ and AZC techniques was fabricated in TSMC 0.35µm 2P4M CMOS process with small compensation capacitors 5pF and 1.5pF. Experimental results demonstrate that the minimum load can be reduced to about 50µA and transient response time can be reduced by the MQ and AZC techniques to be smaller than 4µs. The measured load and line regulation are 20µV/mA and 3.3mV/V respectively.