LDO of High Power Supply Rejection with Two-Stage Error Amplifiers and Buffer Compensation

Abstract

This study develops a low dropout regulator linear regulator, characterized by a high power supply rejection ratio using ultra-low output resistance buffer and two-stage error amplifiers. The high power supply rejection is based on a closed-loop LDO regulator. The ultra-low output resistance buffer achieves ultra-low output impedance with dual shunt feedback loops, subsequently improving load and line regulations, as well as the transient response for low voltage applications. The proposed LDO regulator linear regulator functions under an input voltage of 1.8~3V, and the output voltage can be maintained at around 1.27V. Moreover, its output voltage is independent of input voltage. The proposed regulator is applicable to light-emitting diode driver integrated circuits. The layout chip area of the LDO linear regulator is 21.5μm × 42.6μm.

A novel high accuracy bandgap reference voltage source

“…Therefore, it is necessary in many circuit structures. The realization of zero temperature coefficient is the superposition of the transistor base-emitter voltage V BE , which has a negative temperature coefficient; a difference voltage ΔV BE , which is characterized by a positive temperature coefficient; and the difference of the base-emitter voltages of two bipolar transistors with different current density (Allen and Holberg, 2016; Razavi, 2017; Chang et al , 2014; Hu et al , 2013). Specific implementation is shown in Figure 1: …”

“…So, it is convenient for the following feedback control circuit to regulate the output voltage better, with the sensitivity and accuracy, achieving a great improvement. The two branches of the two transistors form a simple fully differential amplifier structure, of which the output signal enters the LDO control circuit (Razavi, 2017; Chang et al , 2014). The difference value of the two outputs of the two branches effectively reduces the influence of the power supply noise on the circuit, so that the circuit has a high PSRR.…”