Even-Stage Ring Oscillator Startup With Switchable Potential Fixing
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Solution Overview
Problem
Conventional even-stage ring oscillators face challenges in reliable startup due to insufficient consideration of the energy transition capabilities between inverter circuits and pull-up or pull-down circuits, leading to unstable oscillation initiation.
Innovation Solution
A ring oscillator configuration with an even number of stages of inverters, featuring potential fixing circuits that are switchable between connected and disconnected states, and an adjustment circuit that adjusts the drive capability of the inverters, controlling the potential fixing circuits to be connected initially and then disconnected after a predetermined time, to enhance startup reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If potential fixing circuits are connected during startup to fix the logical state of even-stage ring oscillator, then startup stability is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by connecting potential fixing circuits during the startup phase to establish a definite logical state before normal operation. These circuits are temporarily activated to pull up or pull down specific nodes to predetermined potentials, ensuring the oscillator starts from a known state. After startup completion, the potential fixing circuits are disconnected to restore normal oscillation functionality, thus resolving the contradiction between startup stability and device complexity.
Solution Approach 2:
The patent implements dynamics by making the potential fixing circuits switchable between connected and disconnected states based on operational phase. The circuits are dynamically controlled to be connected during startup for stability and disconnected during normal operation to avoid interference with oscillation, thereby balancing startup reliability with operational flexibility and reduced complexity.
2Reliability
If drive capability of inverters is increased to ensure oscillation startup, then oscillation initiation reliability is improved, but energy consumption increases
Solution Approach 1:
The patent applies preliminary action by temporarily enhancing the drive capability of inverters only during the startup phase. The adjustment circuit increases the drive capability of specific inverters at predetermined timing before and during startup, ensuring reliable oscillation initiation. After startup is complete, the drive capability is reduced to normal levels, thus achieving reliable oscillation startup while minimizing energy consumption during normal operation.
Solution Approach 2:
The patent implements periodic action by controlling the drive capability adjustment in periodic phases: enhanced drive capability is activated during startup periods and reduced during normal operating periods. This periodic modulation of drive capability ensures oscillation initiation reliability when needed while minimizing energy consumption during sustained operation.
3Adaptability or versatility
If even number of inverter stages are used to generate multiple-phase clock signals, then adaptability for even-number systems is improved, but startup reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by preparing the even-stage ring oscillator with predetermined potential states before startup. Potential fixing circuits are activated to establish definite logical states at specific nodes, and adjustment circuits pre-position inverters in favorable states for oscillation initiation. This preliminary preparation overcomes the inherent startup difficulty of even-stage configurations while maintaining the ability to generate multiple-phase clock signals for even-number systems.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the drive capability parameters of individual inverters during startup. The adjustment circuit modifies the drive capability of specific inverters at predetermined timing to create favorable oscillation conditions. This parameter adjustment compensates for the startup reliability issues inherent in even-stage configurations while preserving the adaptability for generating multiple-phase clock signals.
Data Source
AI summary
A ring oscillator including: an oscillation circuit including an even number of inverters connected in a ring configuration, the oscillation circuit outputting a clock signal; plural potential fixing circuits respectively connected between pairs of the inverters, each of plural potential fixing circuits being switchable between a connected and a disconnected state in response to a first control signal; and an adjustment circuit that adjusts a drive capability of the inverters based on a second control signal, wherein, during startup, the drive capability is controlled to be a first capability, in which the potential fixing circuits are connected, by the first control signal, and wherein, after a predetermined time has elapsed after the first control signal is output, the drive capability is controlled to be a second capability, higher than the first capability, in which the potential fixing circuits are disconnected, by the second control signal.