Dynamic current doubling circuit and linear voltage regulator integrated with the circuit

Abstract

The invention discloses a dynamic current doubling circuit and a linear voltage regulator integrated with the circuit. The dynamic current doubling circuit can dynamically regulate the magnitude of the output bias voltage according to the condition of an external output load. The low dropout linear voltage regulator integrated with the dynamic current doubling circuit can couple a leaping voltage to the dynamic current doubling circuit by a capacitor within a very short time when the output voltage leaps, a tail current source current of the differential pairs of a transconductance operational amplifier is increased instantaneously by controlling the magnitude of the bias voltage, the gate voltage of a regulating tube can be regulated rapidly, the problem of low slew rate caused by the slow change of the gate voltage of the regulating tube is solved, and the transconductance of the differential pair tube is increased by the increase of the tail current source current of the differential pairs, thereby increasing bandwidth of LDO (low dropout regulator), and the tail current source current only increases instantaneously without excessive power consumption.

Description

technical field [0001] The invention belongs to the technical field of power supply management, and in particular relates to the design of a low dropout linear regulator (Low Dropout Regulator, LDO). Background technique [0002] Low-dropout linear regulator LDO has the advantages of low cost, low output noise, simple circuit structure, and small chip area, and has become an important circuit in power management chips. [0003] The essence of LDO is to use the stable voltage generated by the bandgap reference and the negative feedback control loop to obtain an output voltage that basically does not change with the environment. Existing typical LDO such as figure 1 As shown, it specifically includes: adjustment tube MP1, error amplifier EA, and resistor feedback network. Its basic working principle is as follows: the resistor feedback network generates the feedback voltage, the error amplifier amplifies the small error signal between the feedback voltage and the reference v...

AI Technical Summary

Problems solved by technology

[0004] In order to have a higher load capacity, generally the area of ​​the adjustment transistor MP1 is relatively large, and a capacitance up to tens of pF is formed on the gate of the adjustment transistor MP1. At the same time, in order to reduce the power consumption of the LDO, the quiescent operating current is very small, so that the LDO The slew rate SR=I G / C par is very small, among them, C par To adjust the grid equivalent capacitance of the transistor, I G Charge and discharge current for the gate, so the gate voltage of the MP1 tube changes slowly, resulting in a slow change in the drain current of the MP1 tube. When the output current jumps, the output voltage takes a long time to recover and stabilize, and will High voltage spikes are generated; at the same time, the static operating current is very small, which will also have a great impact on the bandwidth of the LDO. The differential pair tube transconductance in the error amplifier is And the system bandwidth expression is GB=g M / C par , so a smaller quiescent operating current will reduce the bandwidth of the LDO

Some literatures propose corresponding technical solutions for this problem, such as in the literature: P.Hazucha, T.Karnik, B.A.Bradley, C.Parsons, D.Finan, and S.Borkar, Area-efficient linear regulator with ultra-fast load Regulation, IEEE J.Solid-State Circuits, vol.40, no.4, 933–940 increases the slew rate and bandwidth of the LDO by increasing the current source current of the error amplifier tail current, although the slew rate and bandwidth are improved, but The constant tail current of 6mA will generate a very large power consumption. At the same time, in order to increase the stability of the system, the traditional LDO needs to connect a load capacitor outside the chip, which will increase the system cost.

Images