Dual-Path Oscillator Amplitude Control for Low Noise and Power

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Solution Overview

Problem

High frequency generation circuits face challenges with increased power consumption, noise, and longer startup times due to the need for high gain negative feedback loops, which also introduce noise and unpredictability in amplitude control, especially in mmW communication devices.

Innovation Solution

A dual feedback path system is implemented for amplitude control in frequency generation circuits, where a first feedback path continuously controls oscillator amplitude and a second feedback path provides discrete control of amplitude regulating parameters, allowing the first feedback path to operate at reduced gain, thereby reducing power consumption and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a high gain negative feedback loop is used to control oscillator amplitude, 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 feedback paths: a slow feedback path for coarse amplitude regulation and a fast feedback path for fine amplitude control. This segmentation allows each path to operate at optimized gain levels, preventing the noise and power consumption issues associated with a single high-gain feedback loop while maintaining overall amplitude control accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between different feedback paths based on operating conditions. The slow feedback path handles large-signal amplitude variations, while the fast feedback path handles small-signal variations. This dynamic allocation of control functions allows the system to achieve high amplitude control accuracy without continuously operating at high gain, thereby reducing noise and power consumption.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If a high gain negative feedback loop is used to control oscillator amplitude, 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:

The slow feedback path operates periodically with a longer time constant, making coarse adjustments to the oscillator amplitude. The fast feedback path operates continuously with a shorter time constant for fine adjustments. This periodic action in the slow path reduces average power consumption while maintaining amplitude control accuracy through the complementary fast path.

Inventive Principle:

Principle #19Periodic action

3Object-generated harmful factors

If the bandwidth of the negative feedback loop is reduced 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 feedback system is segmented into two paths with different bandwidth characteristics. The fast feedback path has a wider bandwidth that enables rapid response during oscillator startup, while the slow feedback path has a narrower bandwidth that reduces noise during steady-state operation. This segmentation resolves the contradiction between noise reduction and startup time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically utilizes different feedback paths during different operational phases. During startup, the fast feedback path is actively used to quickly establish oscillation. During steady-state operation, the slow feedback path becomes dominant for noise reduction. This dynamic utilization of different bandwidth characteristics resolves the contradiction between noise reduction and startup time.

Inventive Principle:

Principle #15Dynamics

4Object-generated harmful factors

If the bandwidth of the negative feedback loop is reduced to reduce noise, then noise is reduced, but filter size increases

Engineering Contradiction:

ImprovenoiseVSAvoidfilter size

Core Design Contradiction:

Object-generated harmful factorsVSArea of stationary object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using a single large filter to reduce noise, the invention uses two smaller feedback paths with different characteristics. The slow feedback path effectively acts as a noise-filtering mechanism without requiring a large physical filter, thereby reducing the overall filter size while maintaining noise reduction benefits.

Inventive Principle:

Principle #26Copying

Data Source

PatentEP3304742B1Low-noise oscillator amplitude regulator

Publication Date: 2023.03.15 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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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.