Oscillator Circuit Margin Testing Using Built-In Variable Resistance

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Solution Overview

Problem

The challenge lies in predicting and testing the negative resistance design margin of oscillator circuits in microcontrollers, particularly due to process variations and temperature dependence, which can lead to performance issues in mass production, and existing methods require manual modification of printed circuit boards, making it burdensome to test multiple samples.

Innovation Solution

Incorporating built-in variable resistance circuitry within the oscillator circuit that allows for dynamic adjustment of resistance to test and determine the negative resistance margin, using methods such as variable gain stages, phase locked loops, voltage detectors, and pulse-width modulation to monitor and control the oscillator signal quality, enabling testing without manual modification of the PCB.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual modification of PCB is used to test negative resistance margin, then testing can be performed, but the process becomes burdensome and difficult to scale for mass production

Engineering Contradiction:

Improvenegative resistance margin testing accuracyVSAvoidtesting process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The oscillator circuit performs self-testing by internally adjusting its own negative resistance through variable gain amplifier control. The circuit monitors its own oscillation signal quality and automatically determines the negative resistance margin without requiring external manual PCB modifications or test equipment intervention.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The testing functionality is extracted from the external PCB modification approach and integrated directly into the oscillator circuit itself. The margin testing capability is built-in as a separate functional module that operates independently within the oscillator, eliminating the need for manual external modifications.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If process variations and temperature dependence are considered, then more comprehensive testing is needed, but testing time and complexity increase significantly

Engineering Contradiction:

Improveperformance prediction accuracyVSAvoidtesting time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The oscillator circuit dynamically adjusts its negative resistance in real-time during operation to track changing conditions. The variable gain amplifier continuously modifies the oscillation signal characteristics, allowing the circuit to adapt to temperature variations and process deviations without requiring separate static tests for each condition.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The margin testing operates continuously during normal oscillator operation rather than requiring separate discrete test steps. The circuit continuously monitors oscillation signal quality and adjusts negative resistance accordingly, enabling simultaneous production operation and testing without interrupting the manufacturing flow.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS11329608B1Oscillator circuit with negative resistance margin testing

Publication Date: 2022.05.10 INFINEON TECHNOLOGIES AG

AI summary

Systems, methods, and circuits are provided for facilitating negative resistance margin testing in an oscillator circuit. An example oscillator circuit includes amplifier circuitry configured to be coupled in parallel with a resonator and variable resistance circuitry configured to, in response to a resistance control signal, adjust a resistance of the oscillator circuit.