Temperature-Compensated Ring Oscillator for Stable Frequency
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Solution Overview
Problem
Existing ring oscillators are significantly affected by temperature variations, which impact the stability and precision of integrated circuits used in various applications, including communication terminals.
Innovation Solution
A low-temperature coefficient ring oscillator is designed, incorporating a temperature tracking compensation circuit, an inverter oscillation circuit, and a buffer shaping circuit. This configuration uses temperature-dependent impedance of PMOS and NMOS transistors in a diode connection mode to generate a power supply voltage that compensates for temperature-induced frequency variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a typical ring oscillator is used with simple inverter delay units, then the device complexity is low and ease of manufacture is high, but the temperature coefficient is high and stability under temperature variation is poor
Solution Approach 1:
The ring oscillator is divided into multiple delay units, each consisting of an inverter and a capacitor. This segmentation allows independent optimization of each unit's temperature characteristics while maintaining the overall oscillation function.
Solution Approach 2:
The patent implements a feedback mechanism where the oscillation frequency is continuously monitored and compared against a reference, and the delay units are adjusted accordingly to compensate for temperature-induced frequency drift, thereby improving stability.
2Reliability
If the resistance along the charging and discharging path is reduced to minimize temperature influence, then the temperature coefficient is reduced, but the manufacturing precision requirements increase due to tighter control needs
Solution Approach 1:
The patent changes the key parameter from resistance-based delay to capacitance-based delay. By making the delay time primarily dependent on capacitor charging/discharging characteristics rather than resistive paths, the temperature coefficient is reduced since capacitor values are less sensitive to temperature variations.
Solution Approach 2:
The patent utilizes the charging and discharging phases of capacitors as the core timing mechanism. Each delay unit operates through distinct charge and discharge phases, providing stable and predictable delay characteristics that are less affected by temperature.
Data Source
AI summary
Disclosed in the present invention are a low-temperature coefficient ring oscillator, a chip, and a communication terminal. The low-temperature coefficient ring oscillator comprises a temperature tracking compensation circuit, an inverter oscillation circuit, and a buffer shaping circuit. The temperature characteristics of the impedance of a PMOS tube and an NMOS tube in an inverter in the inverter oscillation circuit are tracked and compensated for by means of the impedance, along with temperature change, of a PMOS tube and a NMOS tube connected by a diode.