Low dropout voltage regulator with variable bandwidth based on load current
US6465994B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 27, 2002 |
| Grant date | Oct 15, 2002 |
| Priority date | — |
| Expiry date | Mar 27, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05F1/575
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A low dropout voltage regulator includes: a first amplifier A1 having a reference voltage node VREF coupled to a first input; a second amplifier A2 having an input coupled to an output of the first amplifier A1; a variable bias current source I1 coupled to the first amplifier A1 and having a control node coupled to an output of the second amplifier A2; a power switch M1 having a control node coupled to the output of the second amplifier A2 and having a first end coupled to a source voltage node VDD; and a feedback circuit R1 and R2 having an input coupled to a second end of the power switch M1 and an output coupled to a second input of the first amplifier A1. The best node in the system that detects the load current level is the output of the second amplifier A2. This signal is used to modulate the bias current I1 of the first amplifier A1 by increasing the bias current when the load current increases and vice versa, which consequently modulates the transconductance of amplifier A1. This provides a higher bandwidth LDO with better transient performance and higher power supply rejection ratio.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.