Digitally Trimmed Clock Oscillator With Low-Drift Time Base
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Solution Overview
Problem
Integrated circuits with internal oscillators face challenges in achieving high precision, particularly for applications like CANFD, which require precision beyond ±1%, necessitating external components or advanced circuitry.
Innovation Solution
A high precision oscillator with a low drift time base is used as a reference for a digitally controlled oscillator, incorporating a digital trimming function and a counter to generate a trimming code for the oscillator, allowing for precise frequency adjustment without calibrating the time base itself, thus reducing drift and achieving ±0.2% frequency deviation over temperature and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an internal oscillator is used in integrated circuits, then device complexity is reduced and ease of manufacture is improved, but manufacturing precision and measurement precision deteriorate (achieving only ±1% precision)
Solution Approach 1:
The patent introduces a low drift time base as an intermediary reference element that mediates between the internal oscillator and the desired precision. This time base, implemented through specific RC circuits with temperature compensation, serves as a stable reference against which the oscillator frequency is measured and adjusted, enabling ±0.2% precision without external components
Solution Approach 2:
The patent applies parameter changes by implementing digital trimming of the oscillator frequency based on temperature and voltage conditions. The system dynamically adjusts oscillator parameters using lookup tables and correction factors stored in memory, changing the operating parameters to maintain precision across varying environmental conditions
2Manufacturing precision
If external crystal or clock recovery is used to achieve high precision, then measurement precision is improved (±0.4% or better), but device complexity increases and ease of manufacture deteriorates
Solution Approach 1:
The patent extracts the critical precision-functioning element (the low drift time base) from the external component category and integrates it internally using standard RC circuits with temperature compensation. By taking out the essential reference function and embedding it within the IC, the system achieves external-crystal-level precision without the associated complexity and cost
Solution Approach 2:
The patent creates an internal copy of the reference function that external crystals provide. Through carefully designed RC time base circuits with temperature compensation, the system replicates the stable reference characteristics of external crystals, eliminating the need for separate external components while maintaining precision
3Ease of operation
If traditional internal oscillators are used, then ease of operation is improved, but stability of the object's composition deteriorates (frequency drift over temperature and voltage)
Solution Approach 1:
The patent implements feedback mechanisms where the oscillator output is continuously monitored against the low drift time base reference. The system measures frequency deviations and applies corrective trimming signals back to the oscillator, creating a closed-loop control system that maintains frequency stability despite temperature and voltage variations while requiring minimal user intervention
Data Source
AI summary
A clock oscillator includes a high speed oscillator generating a high speed clock signal and comprising a digital trimming function; a counter receiving said high speed clock signal at a clock input; a time base having a low drift and controlling said counter, wherein the counter generates a difference between a reference value and a counter value; and a digital integrator receiving said difference value and providing trimming data for said high speed oscillator.