RC Oscillator Circuit With Supply-Insensitive Timing
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Solution Overview
Problem
RC oscillators in integrated circuits are sensitive to supply voltage variations, leading to unstable oscillation signal periods due to capacitance characteristics changing with voltage, which can be undesirable in portable devices where space and power are limited.
Innovation Solution
An oscillator circuit design that includes a control circuit, charging circuit, and discharging circuit, where the capacitance is charged and discharged using currents proportional to the supply voltage, maintaining a constant oscillation period by clamping the voltage between reference voltages, thus making the oscillation signal insensitive to supply voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage regulator is used to maintain stable oscillation signal period, then the oscillation period stability is improved, but the integrated circuit occupies more space and consumes more power
Solution Approach 1:
The patent removes the voltage regulator component from the oscillator circuit, extracting the harmful element that consumes power and occupies space. The oscillator is designed to inherently compensate for voltage variations through its charging and discharging current mechanisms, eliminating the need for external voltage regulation while maintaining stable oscillation period.
Solution Approach 2:
The oscillator circuit performs self-regulation by using supply voltage-proportional charging and discharging currents that automatically compensate for voltage variations. The circuit monitors its own operating conditions and adjusts its internal parameters accordingly, making external voltage regulation unnecessary and reducing overall power consumption.
2Use of energy by stationary object
If the supply voltage is left unregulated to reduce power consumption, then the power consumption is reduced, but the oscillation signal period varies with supply voltage changes
Solution Approach 1:
The patent changes the operating parameters of the oscillator by using charging and discharging currents that are directly proportional to the supply voltage. This parameter adjustment allows the oscillator to maintain a constant period TOSC despite voltage variations, as the proportional change in current compensates for the voltage fluctuation effect on the RC time constant.
Solution Approach 2:
The oscillator incorporates implicit feedback mechanisms where the supply voltage level is sensed and automatically reflected in the charging and discharging current magnitudes. This feedback loop ensures that when supply voltage changes, the current adjustments maintain a constant oscillation period without requiring external regulation.
3Reliability
If voltage regulation is implemented to maintain constant oscillation period, then the oscillation period stability is improved, but the device complexity increases
Solution Approach 1:
The patent extracts and removes the voltage regulator subsystem from the overall circuit architecture, simplifying the device by eliminating unnecessary components. The oscillator relies on its inherent voltage-proportional current characteristics rather than external regulation, reducing circuit complexity while maintaining reliability.
Solution Approach 2:
The charging and discharging circuits serve multiple functions simultaneously: they generate the oscillation signal, compensate for voltage variations, and provide the timing function all in one integrated structure. This multi-functionality eliminates the need for separate voltage regulation circuits, reducing overall device 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 circuit achieves a stable oscillation signal period with minimal variation (<10%) despite supply voltage changes, reducing the need for voltage regulation and minimizing power consumption.
Implementation Method 1
One type of oscillator is an RC (resistance-capacitance) oscillator that provides an oscillation signal by charging and discharging a capacitance through a resistance
Data Source
AI summary
Apparatuses and methods are disclosed for oscillators that are substantially insensitive to supply voltage variations. In one such example apparatus, a capacitance circuit is configured to be charged and discharged. Charging and discharging circuits are coupled to the capacitance circuit and configured to charge and discharge, respectively, the capacitance circuit by charging and discharging currents responsive to charge and discharge signals. A control circuit is coupled to the charging circuit and the discharging circuit, and is configured to provide the charge and discharge signals responsive to a voltage of the capacitance circuit, and is further configured to provide an oscillation signal responsive to the voltage of the capacitance circuit. The charging current, the discharging current, or both the charging and discharging currents are proportional to a difference between a first reference voltage and a second reference voltage.