Relaxation Oscillator Bias Memory for Fast Low-Power Startup
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Solution Overview
Problem
Relaxation oscillators in integrated circuits face significant current consumption and prolonged settling time when restarted, limiting power-down opportunities and increasing power usage in power-sensitive applications.
Innovation Solution
An oscillator arrangement with a relaxation oscillator that has an active and inactive state, utilizing a bias current circuit to store internal voltage values and generate bias current upon startup, along with an electronic switch to isolate the oscillator, allowing for rapid and accurate clock signal restoration without the need for external components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the relaxation oscillator is powered down to reduce current consumption, then power usage decreases, but the oscillator has significant settling time when restarted which limits power-down opportunities
Solution Approach 1:
The patent stores the bias current value in a memory element before powering down the oscillator. When restarted, the stored bias current value is immediately loaded to set the oscillator frequency, eliminating the settling time that would otherwise be required for the oscillator to stabilize after power-down.
Solution Approach 2:
The patent replaces the traditional time-based settling process with an electronic memory-based approach. Instead of waiting for the oscillator to naturally stabilize after power-up, the system uses memory to store and recall bias current values, substituting electronic storage and retrieval for the mechanical/time-based settling process.
2Reliability
If the relaxation oscillator is kept running to avoid settling time, then accurate clock signal is available immediately, but current consumption increases
Solution Approach 1:
The bias current value is predetermined and stored in memory before the oscillator needs to operate. This preliminary storage of the correct bias value allows the oscillator to immediately produce an accurate clock signal upon startup without requiring continuous operation or settling time, thus reducing energy consumption while maintaining reliability.
3Measurement precision
If a high-frequency crystal oscillator is used for clock source, then timing precision is improved, but current consumption increases significantly
Solution Approach 1:
The patent changes the operating frequency parameter of the oscillator from high-frequency (crystal oscillator range) to low-frequency (relaxation oscillator range). By using a low-frequency relaxation oscillator with stored bias current values, the system achieves adequate timing precision for power-sensitive applications while dramatically reducing current consumption compared to high-frequency crystal oscillators.
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
Enables fast start-up of the relaxation oscillator with minimal current consumption during the inactive state, reducing power usage and enabling shorter power-down periods without the typical settling time delays, thus providing an accurate clock signal quickly.
Implementation Method 1
the internal voltage value is stored in a capacitor connected to the gate
Data Source
AI summary
An oscillator arrangement is provided, comprising a relaxation oscillator having an active state and an inactive state; a bias current circuit portion arranged to provide a bias current to the relaxation oscillator during said active state; and an electronic switch arranged to isolate said relaxation oscillator from the bias current circuit portion when in said inactive state. The oscillator arrangement is arranged to store an internal voltage value associated with said bias current and the bias current circuit portion is arranged to use the stored internal voltage value to generate the bias current when the oscillator is started up from the inactive state to the active state.