Single-Pin RC Oscillator Feedback for Accurate Clock Frequency
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Solution Overview
Problem
Single-pin RC oscillators face challenges in achieving high frequency accuracy due to variations in response times of oscillator components with voltage and temperature, lacking input/output means for correction.
Innovation Solution
A single-pin input interface senses the voltage across an RC network, with a measurement circuit setting thresholds and a clock generation circuit adjusting the output clock signal frequency based on measured time durations, using a free-running oscillator and frequency divider with a programmable division ratio, to produce highly accurate clock signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single-pin RC oscillator configuration is used, then the pin count is reduced, but the frequency accuracy deteriorates due to component variations with voltage and temperature
Solution Approach 1:
The patent employs feedback by measuring the actual time duration of the RC network charging/discharging cycle and using this measurement to adjust the output clock frequency. The system continuously monitors the RC cycle time and modifies the clock signal frequency to compensate for component variations, thereby maintaining accurate frequency despite using a single-pin configuration with limited external components.
Solution Approach 2:
The system dynamically changes the clock frequency parameter based on measured RC cycle times. By adjusting the clock frequency in response to measured variations in RC network behavior (caused by voltage and temperature changes), the system maintains accurate timing relationships while using a simplified single-pin configuration.
2Device complexity
If traditional RC oscillator circuits are used, then the circuit structure is simple, but the frequency stability deteriorates due to lack of correction mechanisms
Solution Approach 1:
The patent introduces feedback by measuring the actual RC cycle time and using this information to adjust the clock frequency. This feedback mechanism compensates for drift caused by voltage and temperature variations without significantly increasing circuit complexity, as the measurement and adjustment are integrated into the existing oscillator architecture.
Solution Approach 2:
The oscillator system performs self-correction by automatically measuring its own RC cycle time and adjusting its output frequency accordingly. This self-service mechanism enables the circuit to maintain stable frequency without requiring external correction components or complex control systems, keeping the overall structure simple while improving stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution generates clock signals with minimal frequency variation, unaffected by internal inaccuracies, and reduces the total pin count, achieving high accuracy and stability in small form factor devices.
Implementation Method 1
a series resistor-capacitor combination is coupled across a source of supply potential so that the capacitor charges toward the supply potential through the resistor
Implementation Method 2
the capacitor charges toward the supply potential through the resistor
Data Source
AI summary
Apparatus includes a single-pin input interface, which is operative to sense a voltage across a capacitor of a Resistor-Capacitor (RC) network in which the capacitor is repetitively charging and discharging so that the voltage oscillates as a function of time. A measurement circuit is coupled to measure time durations in which the capacitor is charging and in which the sensed voltage lies between first and second predefined thresholds. A clock generation circuit is coupled to generate an output clock signal having a frequency, and to adjust the frequency responsively to the measured time durations.