PSRR Regulator with Output-Powered Reference Circuit

Solution Overview

Problem

Conventional regulators face challenges in maintaining a high power supply rejection ratio (PSRR) due to input supply noise, which affects the stability of the output voltage, and they often have long start-up times due to the delay between input power availability and regulated power stability.

Innovation Solution

A regulator circuit with a reference generator power selector that powers the reference generator circuit from the input power signal during start-up and from a regulated power signal during steady-state operation, reducing noise and improving PSRR while minimizing start-up time through a 'boot-strapping' mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the reference generator circuit is powered from the input power signal during start-up, then the start-up time is reduced, but the noise on the reference signal increases and PSRR deteriorates

Engineering Contradiction:

Improvestart-up timeVSAvoidnoise on reference signal

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The reference generator circuit is pre-powered from the unregulated input power source during start-up to establish reference voltage quickly, then switched to regulated power source once stable to eliminate noise. This preliminary action from unregulated source enables fast start-up, and the subsequent switch to regulated source eliminates the noise harmful effect.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The power source for the reference generator circuit is dynamically switched between unregulated input power during start-up and regulated power during steady-state operation. This dynamic switching allows the system to optimize between fast start-up (using unregulated power) and low noise operation (using regulated power), resolving the contradiction between start-up time and noise performance.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If the reference generator circuit is powered from the regulated power signal during steady-state operation, then the noise on the reference signal is reduced and PSRR is improved, but the start-up time increases

Engineering Contradiction:

Improvenoise on reference signalVSAvoidstart-up time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The reference generator circuit is pre-powered from the unregulated input power source during start-up to establish reference voltage quickly, then switched to regulated power source once stable to eliminate noise. This preliminary action from unregulated source enables fast start-up, and the subsequent switch to regulated source eliminates the noise harmful effect.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The power source for the reference generator circuit is dynamically switched between unregulated input power during start-up and regulated power during steady-state operation. This dynamic switching allows the system to optimize between fast start-up (using unregulated power) and low noise operation (using regulated power), resolving the contradiction between start-up time and noise performance.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If conventional regulators are used to provide constant output voltage, then the output stability is maintained, but the power supply rejection ratio is insufficient due to input supply noise

Engineering Contradiction:

Improveoutput voltage stabilityVSAvoidinput supply noise effect

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

A dedicated reference generator circuit powered from a separate regulated power source serves as an intermediary between the input power and the output regulation. This intermediary reference circuit provides a clean, noise-free reference voltage that is isolated from input supply noise, enabling the regulator to maintain high output stability and reject input noise effectively.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The regulated power source that powers the reference generator circuit is derived from the regulator's own output, creating a self-service loop. The regulator uses a portion of its regulated output to power its reference circuit, ensuring the reference is always derived from clean, regulated power rather than noisy input power, thereby self-correcting for high PSRR performance.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS7804284B1PSRR regulator with output powered reference

Publication Date: 2010.09.28 NAT SEMICON CORP

AI summary

The invention relates to a regulator with a reference generator circuit (e.g., a band-gap reference) and a reference generator power selector. The reference generator power selector selectively powers the reference generator circuit from an input power signal during start-up and from a regulated power signal during steady-state operation. The reference generator power selector may also select from multiple regulated power signals during steady-state operation.