Compensated Oscillator Circuit for Stable Frequency Across Temperature
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Solution Overview
Problem
Existing oscillator circuits face challenges in maintaining a constant oscillation frequency due to variations in temperature and power supply voltage, requiring complex designs that are difficult to implement.
Innovation Solution
The proposed oscillator circuit includes a current source with an amplifier, resistors, and inverters, a vibrator circuit with capacitors, and a latch circuit, which automatically compensates for temperature and supply voltage variations by using resistors with positive and negative temperature coefficients and a current mirror to generate stable oscillation signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional oscillator circuit designs are used to compensate temperature variations, then oscillation frequency stability is improved, but circuit complexity increases and implementation becomes difficult
Solution Approach 1:
The patent uses resistors with positive and negative temperature coefficients to compensate for temperature variations. By changing the temperature coefficient parameters of the resistors, the circuit automatically adjusts to maintain stable oscillation frequency without complex compensation circuits. The current source uses resistors whose resistance changes with temperature in opposite directions, creating a balancing effect that stabilizes the oscillation frequency across temperature ranges.
2Reliability
If complex compensation circuits are implemented, then oscillation frequency stability under supply voltage variations is improved, but ease of manufacture deteriorates
Solution Approach 1:
The oscillator circuit performs self-compensation for supply voltage variations through the inherent characteristics of the current source and vibrator circuit. The circuit automatically adjusts its operation to maintain stable frequency without requiring external reference voltages or complex compensation mechanisms. The inverter threshold voltages and resistor values are selected to provide automatic stabilization, making the circuit easy to manufacture and implement.
3Measurement precision
If high-speed analog comparators and reference voltages are used, then measurement precision of oscillation frequency is improved, but device complexity increases
Solution Approach 1:
The patent replaces expensive high-speed analog comparators and reference voltage circuits with simpler digital logic elements (inverters). The inverter-based threshold detection provides sufficient precision for oscillation frequency control without the complexity and cost of analog comparators. This substitution maintains adequate measurement precision while dramatically simplifying the circuit architecture and reducing component requirements.
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 circuit provides stable and accurate clock signals that are insensitive to temperature and supply voltage variations, simplifying implementation and eliminating the need for high-speed analog comparators and reference voltages, while allowing for calibration to adjust resistance and capacitance for precise frequency control.
Implementation Method 1
the first resistor has a positive temperature coefficient and the second resistor has a negative temperature coefficient
Data Source
AI summary
An oscillator circuit includes a current source comprising an amplifier, a first resistor, a second resistor, and a third inverter whose input and output are connected and coupled with an input of the amplifier. The amplifier is configured to generate a first current flowing through the first resistor and the second resistor. The oscillator circuit also includes a vibrator circuit comprising a first capacitor and a second capacitor, wherein the first capacitor is configured to charge in response to the first current and discharge when the voltage across the first capacitor reaches a first threshold voltage of a first inverter and the second capacitor is configured to charge in response to the first current and discharge when the voltage across the first capacitor reaches a second threshold voltage of a second inverter and a latch circuit comprising the first inverter and the second inverter, wherein the latch circuit is configured to produce an oscillating signal in response to the charging and the discharging of the first capacitor and the second capacitor in the vibrator circuit.