Oscillator Frequency Trimming Using Temperature-Compensated Reference Voltage
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Solution Overview
Problem
Current oscillator trimming techniques are time-consuming and costly, requiring prolonged heating and sweeping of trim values to compensate for temperature and process variations, limiting manufacturing efficiency.
Innovation Solution
A method that generates a pair of voltages, one temperature variant and one invariant, scaled by trim factors to create a reference voltage that compensates for errors within the oscillator system, allowing for efficient trimming during manufacturing and accurate frequency control post-manufacture without physical heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If physical heating and trial-and-error trimming is used to compensate for temperature variations, then frequency accuracy across temperature is improved, but trimming time and manufacturing cost increase substantially
Solution Approach 1:
The patent applies preliminary action by pre-characterizing the temperature dependencies of resistive and capacitive devices during manufacturing. Trim values are calculated in advance based on measured temperature coefficients, rather than determining them through time-consuming trial-and-error heating processes. This allows the oscillator to be pre-configured with compensation parameters that can be quickly applied during operation.
Solution Approach 2:
The patent replaces the mechanical/thermal trimming process (physical heating and manual adjustment) with an electrical/computational system. Temperature compensation is achieved through digital calculation of trim values based on pre-measured device characteristics, eliminating the need for physical heating and iterative mechanical adjustment during trimming.
2Manufacturing precision
If physical heating and sweeping of trim values is performed at various temperatures, then temperature-dependent errors are compensated, but manufacturing productivity decreases
Solution Approach 1:
The patent performs the time-consuming measurement and characterization work in advance during device fabrication. Temperature coefficients of resistors and capacitors are measured and stored as lookup tables or mathematical models before the oscillator needs operation. This preliminary characterization enables rapid trim value calculation without requiring repeated heating cycles during production.
Solution Approach 2:
The patent creates a simplified model or lookup table that copies the essential temperature behavior of the devices. Instead of physically replicating the heating and measurement process for each oscillator trim, the system uses pre-captured temperature characteristics to directly determine appropriate trim values, dramatically reducing per-unit trimming time.
3Manufacturing precision
If precise manufacturing process specifications are used for resistive and capacitive devices, then temperature and process errors are reduced, but manufacturing cost per unit IC increases
Solution Approach 1:
The patent enables the oscillator system to self-correct for process variations through automatic trim value calculation. Instead of requiring expensive precision manufacturing processes to minimize variations, the system measures the actual device characteristics and automatically calculates compensation trim values, allowing standard manufacturing processes to be used while still achieving high accuracy.
Solution Approach 2:
The patent changes the approach from controlling device parameters during manufacturing (which increases cost) to adjusting operational parameters (trim values) after manufacturing. By measuring actual device parameters and calculating compensating trim values, the system achieves precision without requiring expensive precision manufacturing processes.
Data Source
AI summary
Techniques to compensate for sources of temperature and process dependent errors within an oscillator system for frequency control oscillator output clock signal. The oscillator system may include a controller and an oscillator circuit. The techniques may include generating a pair of voltages, a first of which is temperature variant, having (approximately) known temperature variations across process, and a second of which is (approximately) temperature invariant. Each voltage may be scaled by a corresponding trim factor. The scaled voltages may be combined to generate a reference voltage. The reference voltage may compensate for process and temperature dependent error sources within the oscillator system to set the oscillator output clock signal frequency.