Bias-Controlled Ring Oscillator for Temperature-Stable Fast Start/Stop
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Solution Overview
Problem
Current starved ring oscillators face challenges in temperature compensation and tuning across multiple oscillation frequencies, along with significant start/stop transients, making them difficult to manage effectively.
Innovation Solution
The design incorporates a chain of cascade-coupled inverter stages with specific transistor configurations and a biasing circuit that allows for temperature compensation and fast start/stop operations by controlling the conductivity and channel lengths of transistors, enabling reduced or absent start/stop transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If current starved ring oscillators are used to achieve high speed and low power consumption, then power consumption is reduced and speed is improved, but temperature compensation becomes difficult and start/stop transients are uncontrolled
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the bias current through a control circuit that modifies the conductivity of bias transistors based on temperature conditions. This allows the oscillator to maintain stable frequency across temperature variations while preserving the low power consumption benefits of current starved operation.
Solution Approach 2:
The patent implements feedback through a temperature sensing mechanism that monitors oscillator behavior and adjusts bias currents accordingly. This feedback loop enables automatic temperature compensation without requiring manual intervention, resolving the contradiction between low power operation and temperature stability.
2Speed
If current starved ring oscillators are used to achieve high speed and low power consumption, then power consumption is reduced and speed is improved, but start/stop operation produces uncontrolled transients
Solution Approach 1:
The patent applies preliminary action by pre-charging or pre-biasing the oscillator circuit before actual operation begins. This preparation step ensures that when the oscillator starts or stops, transitions are controlled and predictable, eliminating uncontrolled transients while maintaining high-speed operation during normal oscillation.
Solution Approach 2:
The patent uses dynamics by implementing time-varying bias currents that adapt during start/stop transitions. The bias conditions are dynamically adjusted during transient phases to control behavior, then returned to optimal values for steady-state high-speed operation.
3Temperature
If conventional current starved ring oscillators are designed for single frequency operation with temperature compensation, then temperature stability is achieved, but tuning across multiple frequencies becomes difficult
Solution Approach 1:
The patent applies universality by designing a multi-functional bias control circuit that can simultaneously provide temperature compensation and frequency tuning. The control circuit responds to different input signals to achieve either temperature stabilization or frequency adjustment, making the oscillator adaptable to multiple operating conditions without sacrificing temperature stability.
Solution Approach 2:
The patent uses segmentation by separating the control functions into independent pathways - one for temperature compensation and another for frequency tuning. This allows each function to be optimized independently while working together through the unified oscillator structure, enabling both temperature stability and multi-frequency operation.
Data Source
AI summary
In an embodiment a ring oscillator circuit includes a chain of cascade-coupled inverter stages coupled between an oscillator supply voltage node and a reference voltage node, the oscillator supply voltage node configured to provide an oscillator supply voltage, a current generator circuit coupled between the oscillator supply voltage node and a system supply voltage node configured to provide a system supply voltage, the current generator circuit being configured to inject a current into the oscillator supply voltage node and a biasing circuit including a first bias control transistor and a second bias control transistor coupled in series between the reference voltage node and the oscillator supply voltage node, wherein the first bias control transistor is configured to selectively couple the reference voltage node and the oscillator supply voltage node in response to the oscillator control signal being indicative that the ring oscillator circuit is in an inactive operation state.