Hybrid Oscillator Delay Matching for Supply-Voltage Stability
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Solution Overview
Problem
Existing oscillators for ultra-low-cost flexible integrated circuits are sensitive to supply voltage variations, affecting frequency stability, particularly in applications like RFID where power supply can be variable.
Innovation Solution
A hybrid oscillator combining a ring oscillator stage with an RC oscillator stage, where the voltage response characteristics of both stages are inversely correlated to cancel out frequency variations, ensuring stable output frequency over a range of supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ring oscillator or RC oscillator is used for low-cost IC applications, then the area requirement and power consumption are reduced, but the frequency stability becomes sensitive to supply voltage variations
Solution Approach 1:
The patent combines a ring oscillator stage and an RC oscillator stage into a single hybrid oscillator circuit. The ring oscillator provides voltage-dependent frequency characteristics while the RC oscillator provides inverse voltage-dependent characteristics, and their combination cancels out voltage variations to achieve stable frequency output.
Solution Approach 2:
The patent converts the harmful effect of voltage variations into a beneficial cancellation mechanism. By designing the ring oscillator stage to have positive voltage coefficient and the RC oscillator stage to have negative voltage coefficient, the voltage variations that would normally destabilize the frequency are instead used to cancel each other out, transforming the sensitivity problem into a stability solution.
2Reliability
If crystal oscillators are used to achieve stable frequency, then frequency stability is improved, but the space requirement and overall complexity increase
Solution Approach 1:
The patent creates an artificial oscillation system that copies the frequency stability function of crystal oscillators using only standard IC components. Instead of using a physical crystal resonator, the hybrid oscillator uses the interaction between the ring oscillator stage and RC oscillator stage to generate stable frequency, achieving crystal-like performance with simpler integrated circuit implementation.
3Reliability
If LC oscillators are used for high frequency applications, then frequency stability is improved, but the area requirement for the inductor increases
Solution Approach 1:
The patent replaces the mechanical inductor component with an electrical equivalent circuit implementation. Instead of using a physical inductor that occupies significant chip area, the oscillator uses combinations of resistors, capacitors, and transistor-based delay elements to achieve the same oscillation function, eliminating the need for large inductor area while maintaining frequency stability.
Data Source
AI summary
There is provided an oscillator, having an input terminal (In) and an output terminal (Out), comprising a first signal delay circuit (104a-d), having a first voltage response characteristic, configured to provide a predetermined first propagation delay; a second signal delay circuit (104e, 108, 110), having a second voltage response characteristic that is inversely correlated to said first voltage response characteristic, operatively coupled with said first signal delay circuit and configured to provide a predetermined second propagation delay, and wherein said predetermined first propagation delay and said predetermined second propagation delay are temporally matched, so as to generate an oscillating output signal (Out) of a predetermined frequency.