Programmable Ring Oscillator With Schmitt Trigger Frequency Stabilization
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Solution Overview
Problem
Current ring oscillators in wireless devices are susceptible to variations in supply voltage, leading to inaccurate and unstable clock signals, particularly in low-power applications where power consumption needs to be minimized.
Innovation Solution
A programmable ring oscillator incorporating a Schmitt trigger, CMOS inverters, resistors, and a capacitor, where the Schmitt trigger provides input hysteresis with threshold voltages adjustable based on supply voltage and configuration signals to maintain a constant oscillation frequency, reducing the impact of voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a ring oscillator is used in low-power state, then power consumption is reduced, but frequency stability and accuracy deteriorate due to supply voltage variations
Solution Approach 1:
The patent implements a feedback mechanism where the oscillation frequency is monitored and compared against a target frequency. Based on the frequency error detected, the system dynamically adjusts the hysteresis width of the Schmitt trigger to compensate for supply voltage variations. This closed-loop feedback ensures frequency stability while maintaining low power consumption in sleep state.
Solution Approach 2:
The patent dynamically changes the hysteresis width parameter of the Schmitt trigger based on detected oscillation frequency and supply voltage conditions. By adjusting this parameter in real-time, the system compensates for voltage-induced frequency drift without increasing power consumption, thus resolving the contradiction between low power usage and frequency stability.
2Use of energy by moving object
If supply voltage varies in low-power applications, then power consumption is reduced, but clock signal accuracy deteriorates
Solution Approach 1:
The system continuously monitors the actual oscillation frequency and compares it with the desired frequency accuracy requirement. When frequency deviation is detected due to supply voltage variations, the feedback loop adjusts the Schmitt trigger hysteresis width to bring the frequency back within acceptable bounds, maintaining clock signal accuracy while preserving low-power operation.
Solution Approach 2:
The oscillator circuit performs self-correction by automatically adjusting its own hysteresis parameter based on its detected frequency deviation. This self-service mechanism allows the circuit to maintain accurate clock signals without external intervention or additional power-consuming correction circuits.
3Device complexity
If hysteresis width is fixed in ring oscillator, then device complexity is reduced, but frequency stability under voltage variations worsens
Solution Approach 1:
The patent transforms the fixed hysteresis width into a dynamic parameter that can be adjusted in real-time. The Schmitt trigger's hysteresis width is no longer static but varies adaptively based on supply voltage levels and oscillation frequency, enabling frequency stability without requiring complex external control circuits.
Solution Approach 2:
The oscillator circuit automatically adjusts its own hysteresis parameter without external control signals or complex feedback infrastructure. The self-service capability allows the circuit to maintain frequency stability through intrinsic parameter adaptation, keeping the overall device complexity low while improving reliability.
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 solution stabilizes the oscillation frequency and improves the accuracy of clock signals by dynamically adjusting the hysteresis of the Schmitt trigger in response to changes in supply voltage, enhancing the performance of wireless devices in varying power conditions.
Implementation Method 1
The Schmitt trigger may include input hysteresis having a low threshold voltage and a high threshold voltage
Implementation Method 2
the oscillating frequency may be based on an RC time constant of the first resistor, the second resistor, and the capacitor
Data Source
AI summary
A programmable ring oscillator for a wireless device is disclosed. The programmable ring oscillator includes a Schmitt trigger, first and second CMOS inverters, first and second resistors, and a capacitor. The Schmitt trigger includes an input coupled to a first node, a control terminal coupled to a configuration signal, and an output. The first CMOS inverter includes an input coupled to the output of the Schmitt trigger and an output coupled to a second node. The second CMOS inverter includes an input coupled to the second node and an output coupled to an output terminal configured to provide an output signal having a oscillating frequency. The first resistor is coupled between the output terminal and a third node, and the second resistor is coupled between the third node and the first node. The capacitor is coupled between the second node and the third node.