A Low-Voltage and Power-Efficient Capless LDO Based on the Biaxially Driven Power Transistor Technique for Respiration Monitoring System.

ABSTRACT

In this study, a 0.8-V- Vin 200-mA- Io capless low-dropout voltage regulator (LDO) is developed for a wireless respiration monitoring system. The biaxially driven power transistor (BDP) technique is proposed in the LDO, with a current driven stimulation on the bulk and a voltage on the gate terminal. With the BDP technique, an adaptively biased current-driven loop (ABCL) is designed which can reduce the high threshold voltage of power transistor, thus presenting lower input voltage and reduced power consumption. Moreover, this loop can provide an improved dynamic response due to its increased discharging current. Based on an error amplifier with enhanced DC gain and gain bandwidth, the capless LDO achieves superior power supply rejection (PSR) and stability without a complex frequency compensation mechanism. The proposed LDO is fabricated in the SMIC 180 nm process with a chip area of 0.046 mm 2. Measurement results indicate that this LDO can obtain a 200-mA load current range and greater than -66 dB PSR up to 1 kHz at a supply voltage as low as 0.8 V.