On-Chip Oscillator Synchronization for Stable Sensor IC Timing
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Solution Overview
Problem
Integrated circuits with on-chip sensors require stable frequency communication, but crystal oscillators, which provide stability, cannot be integrated on-chip, leading to additional costs and space requirements due to the need for external connections.
Innovation Solution
An integrated circuit with an on-chip oscillator and a digital phase locked loop that synchronizes its frequency with an external precision oscillator, using a synchronization signal to compensate for environmental and process variations, allowing for a cost-effective and space-saving solution without the need for an external crystal oscillator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crystal oscillator is used to provide stable frequency, then frequency stability is improved, but device complexity and space requirements increase due to additional pins and wiring
Solution Approach 1:
The patent combines the oscillator function directly into the sensor chip by integrating an on-chip oscillator circuit, eliminating the need for separate crystal oscillators and their associated wiring. This merging of functions reduces device complexity while maintaining frequency stability through digital synchronization techniques.
Solution Approach 2:
The patent introduces a digital phase-locked loop (PWL) as an intermediary mechanism that synchronizes the on-chip oscillator with external timing signals. This mediator enables the integrated oscillator to achieve frequency stability comparable to crystal oscillators without requiring direct physical connection to external crystal components.
2Device complexity
If an on-chip oscillator is used to reduce space requirements, then device integration is improved, but frequency stability deteriorates due to environmental influences
Solution Approach 1:
The patent implements a digital phase-locked loop that continuously monitors the oscillator output and adjusts timing parameters based on feedback from synchronization signals. This feedback mechanism compensates for frequency drift caused by temperature variations and other environmental factors, maintaining stable operation despite the oscillator being integrated on the chip.
Solution Approach 2:
The patent adjusts timing parameters and synchronization intervals dynamically to compensate for environmental influences on the on-chip oscillator. By changing operational parameters based on detected conditions, the system maintains frequency stability while keeping the oscillator integrated on the sensor chip.
3Measurement precision
If synchronization signals are transmitted frequently to maintain accuracy, then frequency precision is improved, but communication overhead increases
Solution Approach 1:
The patent employs periodic synchronization signals transmitted at optimized intervals rather than continuously. The digital phase-locked loop is designed to maintain frequency lock between synchronization events, allowing less frequent updates while preserving timing accuracy. This periodic approach reduces communication overhead while maintaining sufficient frequency precision for sensor operations.
Data Source
AI summary
An integrated circuit has an oscillator circuit having an on-chip oscillator, a digital phase locked loop and a sensor. A frequency of an output signal from the oscillator circuit is adjustable. The digital phase locked loop receives the output signal from the oscillator circuit at an input and a synchronization signal based on an output signal from an external precision oscillator in the form of a crystal oscillator or MEMS oscillator at an external interface and generates a control signal in order to synchronize the frequency of the oscillator circuit with the frequency of the external crystal oscillator. The sensor is designed to measure at least one environmental parameter, wherein the digital phase locked loop is designed to take into account the at least one measured environmental parameter when generating the control signal.