Oscillator Amplitude Regulation with Dual Feedback Paths

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Solution Overview

Problem

High frequency generation circuits face challenges with increased power consumption, noise, and longer start-up times due to the need for accurate amplitude control across varying Q-values and PVT conditions, which existing negative feedback loops fail to address effectively without introducing noise or increasing power consumption.

Innovation Solution

A dual feedback path system is implemented, where a first feedback path provides continuous amplitude control and a second feedback path offers discrete control of amplitude regulating parameters, allowing the first feedback path to operate at reduced gain and power consumption while maintaining oscillator performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high gain is used in the negative feedback loop to reduce amplitude variations, then amplitude control accuracy is improved, but noise and power consumption increase

Engineering Contradiction:

Improveamplitude control accuracyVSAvoidnoise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The feedback loop is segmented into two separate paths: a first feedback path for continuous amplitude control and a second feedback path for discrete control of amplitude regulating parameters. This segmentation allows each path to operate with optimized gain levels, reducing the need for high overall gain while maintaining amplitude control accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An intermediary control mechanism is introduced where the second feedback path adjusts amplitude regulating parameters (such as bias current or resonant circuit properties) in discrete steps. This intermediary control reduces the burden on the first feedback path, allowing it to operate with lower gain and thus reducing noise and power consumption.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If high gain is used in the negative feedback loop to reduce amplitude variations, then amplitude control accuracy is improved, but power consumption increases

Engineering Contradiction:

Improveamplitude control accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If bandwidth is reduced in the negative feedback loop to reduce noise, then noise is reduced, but startup time increases

Engineering Contradiction:

ImprovenoiseVSAvoidstartup time

Core Design Contradiction:

Object-generated harmful factorsVSLoss of time

Solution Approach 1:

The second feedback path performs preliminary action by adjusting amplitude regulating parameters during the startup phase and under varying operating conditions. This preliminary adjustment ensures the oscillator reaches its operating point faster, compensating for the reduced bandwidth of the first feedback path and maintaining fast startup times despite lower noise.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically switches between continuous control (first feedback path) and discrete control (second feedback path) based on operating conditions. During startup or when operating conditions change significantly, the second feedback path provides rapid adjustments, while during steady-state operation, the first feedback path provides fine-tuned control with reduced bandwidth for lower noise.

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If different Q-values and PVT conditions are accommodated, then adaptability is improved, but amplitude variations increase

Engineering Contradiction:

Improveadaptability to Q-values and PVT conditionsVSAvoidamplitude stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second feedback path dynamically adjusts amplitude regulating parameters (such as bias current, transistor sizing, or resonant circuit properties) based on detected operating conditions including Q-value variations and PVT conditions. This parameter adaptation compensates for environmental variations and maintains stable amplitude across different operating conditions.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11552641B2Low-noise oscillator amplitude regulator

Publication Date: 2023.01.10 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A frequency generation solution controls an oscillator amplitude using two feedback paths to generate high frequency signals with lower power consumption and lower noise. A first feedback path provides continuous control of the oscillator amplitude responsive to an amplitude detected at the oscillator output. A second feedback path provides discrete control of the amplitude regulating parameter(s) of the oscillator responsive to the detected oscillator amplitude. Because the second feedback path enables the adjustment of the amplitude regulating parameter(s), the second feedback path enables an amplifier in the first feedback path to operate at a reduced gain, and thus also at a reduced power and a reduced noise, without jeopardizing the performance of the oscillator.