Self-Calibrating Oscillator Without a Charge Pump
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Solution Overview
Problem
RC oscillators face limitations in high accuracy and frequency due to variations in power supply voltage, temperature, and manufacturing processes, requiring continuous self-calibration that consumes significant power.
Innovation Solution
A self-calibrating oscillator design that includes a first voltage supply circuit, a second voltage supply circuit, a reset circuit, and a calibration value generation circuit, which use pulse signals and comparators to adjust the frequency based on the difference in time for both voltages to reach a reference voltage, eliminating the need for a charge pump and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous self-calibration is implemented to improve frequency accuracy, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic self-calibration instead of continuous calibration. The calibration circuit operates at specific intervals determined by a calibration period, comparing the RC oscillator output frequency with a reference frequency at periodic moments. This reduces power consumption while maintaining frequency accuracy by performing calibration only when necessary, rather than continuously.
Solution Approach 2:
The patent employs self-service through automatic frequency calibration without external intervention. The calibration circuit automatically detects frequency deviations and adjusts the oscillator parameters using feedback from the frequency comparison result, enabling the system to self-correct and maintain accuracy without continuous external control.
2Measurement precision
If a charge pump is used for frequency calibration to improve measurement precision, then frequency accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the charge pump component from the calibration system. Instead of using a charge pump to generate calibration voltages, the invention uses a simplified calibration circuit that directly compares frequencies and generates calibration signals, removing the complex charge pump architecture while maintaining calibration functionality.
Solution Approach 2:
The patent replaces the charge pump mechanism with an electronic frequency comparison and control system. Instead of using the charge pump's voltage generation mechanism, the invention uses digital or electronic frequency detection and control circuits to achieve the same calibration objective with reduced complexity.
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 oscillator efficiently increases the accuracy of the output frequency by calibrating the oscillation circuit without a charge pump, achieving high accuracy and reducing power consumption through a simple structure and precise calibration.
Implementation Method 1
a first voltage supply circuit which outputs a first voltage that is monotonously changed in accordance with a predetermined time constant
Implementation Method 2
a second voltage supply circuit which outputs a second voltage that is changed by a switching operation corresponding to a frequency of an output signal from the oscillation circuit
Implementation Method 3
a calibration value generation circuit which generates a calibration value corresponding to a time difference between a time when the second voltage reaches a reference voltage from a change initiation time and a reference time when the first voltage reaches the reference voltage from a change initiation time
Data Source
AI summary
An oscillator that increases the accuracy of an output frequency, without using a charge pump, has an oscillation circuit, first and second voltage supply circuits, and a calibration value generation circuit. The first voltage supply circuit includes a resistor and a capacitor, the resistance and capacitance of which are determined so that a first voltage reaches a reference voltage within a reference time. The second voltage supply circuit includes first and second switching means, which perform switching when receiving pulse signals corresponding to the frequency of the oscillation circuit to raise the second voltage. A calibration value generation circuit provides the oscillation circuit with a calibration value that lowers the frequency when the second voltage reaches the reference voltage before the first voltage and raises the frequency when the second voltage reaches the reference voltage after the first voltage.