Ring Oscillator Startup Using Forced Switching Initial Conditions

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional oscillators take too long to restart and stabilize, limiting the frequency at which micro-controllers can enter deep sleep mode for power saving, as the restart process relies on noise amplification and takes hundreds of microseconds, which is too slow for frequent power management.

Innovation Solution

A ring oscillator configuration with a switching inverting amplifier and bias generator responsive to an enable signal, using transistor pairs to impose conflicting initial conditions that force oscillation without noise amplification, allowing for rapid startup by asserting the enable signal, reducing the startup time to 31 nanoseconds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional oscillator restart method using noise amplification is used, then oscillator can be restarted, but restart time is too long (hundreds of microseconds)

Engineering Contradiction:

Improveoscillator restart speedVSAvoidminimum deep sleep duration

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-setting the initial conditions of the oscillator stages through the bias generator before restart is needed. When the enable signal transitions, the bias generator immediately establishes the correct voltage levels and phase relationships, eliminating the need for noise amplification and reducing restart time to nanoseconds.

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If oscillator is switched off to save power, then power consumption is reduced, but restart and stabilization time increases minimum sleep duration

Engineering Contradiction:

Improvepower consumptionVSAvoidminimum sleep mode duration

Core Design Contradiction:

Use of energy by moving objectVSDuration of action of moving object

Solution Approach 1:

The bias generator pre-establishes the operating conditions for the oscillator stages during the sleep mode setup phase. When the enable signal is asserted, the oscillator immediately transitions to oscillation because the initial conditions are already prepared, allowing frequent entry into and exit from deep sleep mode without significant penalty.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If multiple clock domains are used in micro-controller, then power management flexibility is improved, but oscillator restart time becomes critical bottleneck

Engineering Contradiction:

Improvepower management flexibilityVSAvoidoscillator restart speed

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent enables fast oscillator restart which is critical for multi-domain power management. By pre-setting initial conditions through the bias generator, each clock domain can be independently enabled or disabled and restarted rapidly when needed, maintaining the flexibility benefits of multiple clock domains without the restart time bottleneck.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8803617B2Oscillators and clock generation

Publication Date: 2014.08.12 TEXAS INSTRUMENTS INC

AI summary

Oscillator circuitry having a switching inverting amplifier arranged in a ring oscillator configuration of at least two stages. A bias generator for supplying the amplifiers of neighboring stages, is responsive to an enable signal to supply the amplifiers only when the enable signal is asserted. A first pair of transistors, coupled to an input of one of the amplifiers and the other coupled to an output of the amplifier, the transistors being driven in common by the enable signal such that when the enable signal is deasserted the transistors of the pair are turned on to impose conflicting levels at the input and the output such that the amplifier is forced to switch.