VCO Harmonic Filter Calibration for Low Phase Noise

Solution Overview

Problem

Existing voltage-controlled oscillators (VCOs) face challenges in achieving effective phase noise reduction due to deviations in capacitance and inductance values from design specifications, which are caused by process variations, leading to suboptimal performance of second-order harmonic filters.

Innovation Solution

Implementing tunable capacitors in second-order harmonic filters coupled to the VCO, with a measurement circuit to measure the output voltage swing and a control circuit to adjust capacitance settings, allowing for calibration to achieve low phase noise by selecting the optimal capacitance settings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If fixed capacitance values are used in second-order harmonic filters, then the device complexity is reduced, but the phase noise reduction performance deteriorates due to process variations

Engineering Contradiction:

Improveharmonic filter structureVSAvoidphase noise reduction performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies the dynamics principle by making the capacitance values in the second-order harmonic filters tunable rather than fixed. The filters include tunable capacitors that can be adjusted during calibration to compensate for process variations, allowing the system to adapt its parameters dynamically to achieve optimal phase noise reduction performance while maintaining a relatively simple filter structure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by allowing the capacitance values in the harmonic filters to be varied through tuning mechanisms. The calibration process modifies the capacitance parameters of the tunable capacitors to optimize the filter's phase noise reduction effectiveness, directly addressing the performance degradation caused by fixed parameter design under process variations.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If tunable capacitors are added to the harmonic filters, then the phase noise reduction performance is improved, but the device complexity increases

Engineering Contradiction:

Improvephase noise reduction performanceVSAvoidharmonic filter structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by making the capacitance values in the second-order harmonic filters tunable rather than fixed. The filters include tunable capacitors that can be adjusted during calibration to compensate for process variations, allowing the system to adapt its parameters dynamically to achieve optimal phase noise reduction performance while maintaining a relatively simple filter structure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements self-service through an automated calibration process that measures the VCO output and automatically adjusts the tunable capacitor values to optimize phase noise reduction. This self-calibrating mechanism reduces the need for manual tuning and complex design procedures, offsetting the added complexity of the tunable capacitors with automated adjustment capabilities.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If calibration process is implemented, then the manufacturing precision is improved, but the productivity is reduced due to additional calibration steps

Engineering Contradiction:

Improvecapacitance and inductance matchingVSAvoidcalibration time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent implements self-service through an automated calibration process that measures the VCO output and automatically adjusts the tunable capacitor values to optimize phase noise reduction. This self-calibrating mechanism reduces the need for manual tuning and complex design procedures, offsetting the added complexity of the tunable capacitors with automated adjustment capabilities.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent applies preliminary action by performing calibration during the manufacturing or initialization phase to establish optimal capacitor values before the device enters production use. This preliminary tuning ensures that the device achieves its full performance potential from the start, and the calibrated settings can be stored and reused, minimizing the impact on overall productivity.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12463588B2Phase noise reduction for voltage-controlled oscillator using harmonic filter

Publication Date: 2025.11.04 QUALCOMM INC

AI summary

A system includes a voltage-controlled oscillator (VCO), a first second-order harmonic filter coupled to the VCO, wherein the first second-order harmonic filter includes a first tunable capacitor, and a second second-order harmonic filter coupled to the VCO, wherein the second second-order harmonic filter includes a second tunable capacitor. The system also includes a measurement circuit coupled to the VCO, wherein the measurement circuit is configured to measure a voltage swing of the VCO. The system also includes a control circuit coupled to the measurement circuit, the first tunable capacitor, and the second tunable capacitor.