Runtime-Compensated Oscillator Circuit for Stable Clock Frequency
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Solution Overview
Problem
Relaxation oscillators face challenges in generating a stable oscillating signal due to propagation delays in comparators, which can vary with manufacturing processes and external factors like temperature, affecting the frequency of the oscillating signal.
Innovation Solution
The method involves using multiple capacitive storage elements and oscillator units that alternate between active and preset modes, with each unit changing its state based on a fixed charging current, ensuring that the charge difference between states is independent of internal runtime, thereby stabilizing the oscillating signal frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a comparator is used to detect the charging state of the capacitive component, then the oscillating signal frequency can be controlled, but the propagation delay of the comparator causes frequency instability due to variations in manufacturing process and external factors
Solution Approach 1:
The patent extracts and eliminates the comparator component from the oscillator circuit. Instead of using a comparator to detect the charging state of the capacitive component, the invention uses direct voltage comparison through circuit topology where the oscillation frequency is determined solely by RC time constants, removing the source of propagation delay variability.
Solution Approach 2:
The invention changes the detection mechanism from current-based comparator detection to voltage-based direct comparison. By using resistive dividers and direct voltage nodes to determine charging states, the circuit eliminates the need for active comparator components and their associated propagation delays, achieving frequency stability through passive component parameters.
2Reliability
If multiple capacitive storage elements and oscillator units are used to eliminate propagation delay effects, then frequency stability is improved, but device complexity increases
Solution Approach 1:
The oscillator circuit is segmented into multiple identical oscillator units, each with its own capacitive storage element. These units are arranged in a modular fashion where each unit contributes to the overall oscillation frequency through its RC time constant, allowing the system to achieve frequency stability without requiring complex inter-unit communication or control mechanisms.
Solution Approach 2:
Each oscillator unit is designed as a universal module that performs multiple functions: it generates the oscillating signal, detects its own charging state through voltage comparison, and contributes to the overall frequency determination. This multi-functionality reduces the need for additional specialized components and simplifies the overall circuit architecture.
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
This approach generates an oscillating signal with a stable frequency, independent of propagation delays, ensuring consistent clock signal generation across varying conditions.
Implementation Method 1
Each of the oscillator units comprises a capacitive storage element (111, 11n). The first state and the second state are defined by a charging state of the corresponding capacitive storage element, with the charging state being defined by an amount of electrical charge stored in the capacitive storage element.
Implementation Method 2
Changing the charging state includes providing a constant charging current to the capacitive storage element. Charging the capacitive storage element stops when the threshold detector detects that the voltage at a first terminal of the capacitive storage element has crossed a first threshold.
Implementation Method 3
Each threshold detector is connected to detect the charging state of the at least one associated capacitive storage element. Charging the capacitive storage element stops when the threshold detector detects that the voltage at a first terminal of the capacitive storage element has crossed a first threshold.
Data Source
AI summary
Disclosed is a method for generating an oscillating signal and an oscillator circuit.