Dual-Regulator PLL/DLL Circuit for Power Supply Noise Rejection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional phase-locked loops (PLLs) and delay-locked loops (DLLs) suffer from power supply noise rejection issues, which introduce jitter into the output signal due to variations in power supply voltage, affecting the stability of the phase and frequency lock.

Innovation Solution

The implementation of a phase control circuit with two regulators: a first regulator for filtering power supply noise and a second regulator for adjusting the phase and frequency lock, using a signal generator to produce a periodic output signal with parameters dependent on a phase adjust voltage, and a low pass filter to isolate noise from the power supply voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional PLL or DLL uses a single regulator for power supply, then the device complexity is low, but power supply noise varies the phase of the output signal, introducing jitter

Engineering Contradiction:

Improvephase stabilityVSAvoidregulator structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The power supply regulation function is segmented into two independent regulators: a first regulator that provides noise-free power to the phase detector and loop filter, and a second regulator that provides noise-free power to the VCO or VCDL. This segmentation isolates noise-sensitive components from power supply variations, resolving the contradiction between maintaining phase stability and avoiding increased device complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces intermediate filtering stages between the power supply and sensitive components. A low-pass filter is inserted between the first regulator and the phase detector/loop filter, and another low-pass filter is placed between the second regulator and the VCO/VCDL. These intermediary filters act as mediators that further attenuate power supply noise before it reaches the sensitive components, enhancing phase stability without requiring complex regulator designs.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If power supply noise is rejected using traditional filtering methods, then phase stability improves, but the circuit complexity and power consumption increase

Engineering Contradiction:

Improvephase lock stabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the power supply parameters by providing separate regulated voltage rails with different noise characteristics to different parts of the circuit. The first regulator maintains a stable average voltage for the phase detector and loop filter, while the second regulator provides a stable average voltage for the VCO or VCDL. This parameter separation allows each component to operate in its optimal voltage environment, improving phase lock stability without requiring excessive filtering that would increase power consumption.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the power supply voltage is stabilized, then jitter is reduced, but the ability to dynamically adjust phase and frequency response is limited

Engineering Contradiction:

Improvejitter reductionVSAvoidphase control flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic control by allowing the second regulator to respond to control signals that depend on phase differences between the output signal and reference signal. This enables the VCO or VCDL to dynamically adjust its operating point in response to phase errors while the first regulator maintains a stable average power supply voltage. The dynamic response capability is preserved in the phase control path while power supply noise rejection is maintained through the dual-regulator architecture.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution effectively rejects power supply noise, maintaining the stability of the phase and frequency lock in PLLs and DLLs, reducing jitter and ensuring reliable operation.

Implementation Method 1

The first regulator is to filter noise in a power supply voltage between the first and second power supply terminals away from the signal generator

Methodology Applied

Scientific EffectNoise filtering: Filter (electronic)

Implementation Method 2

The second regulator is to adjust the phase adjust voltage in response to a control signal, the control signal being dependent on a phase difference between the output signal and a reference signal

Methodology Applied

Scientific EffectPhase control: Phase Modulation

Implementation Method 3

using a signal generator to produce a periodic output signal with parameters dependent on a phase adjust voltage, and a low pass filter to isolate noise from the power supply voltage

Methodology Applied

Scientific EffectLow pass filtering: Filter (electronic)

Data Source

PatentUS7501867B2Power supply noise rejection in PLL or DLL circuits

Publication Date: 2009.03.10 RAMBUS INC

AI summary

A phase controller can be part of a phase-locked loop (PLL) or a delay-locked loop (DLL). The phase controller includes first and second regulators. The first regulator provides power supply noise rejection while the second regulator provides phase and frequency lock.