Injection-Locked Analog-to-Time Converter for Stable Resonant Frequency
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Solution Overview
Problem
Existing band-pass filter analog-to-time converters face challenges such as low quality factor, complexity in adjusting the resonant frequency, and drift due to PVT variations.
Innovation Solution
A voltage-to-time converter design incorporating a direct path with a first injection-locked oscillator and a feedback loop with an integrator circuit, where the oscillator is controlled by the difference between the input voltage and the feedback loop output, implementing negative feedback to stabilize the resonant frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage-controlled ring oscillators are used to implement band-pass filter function, then the converter can filter signals, but the resonant frequency drifts due to PVT variations and the quality factor is limited
Solution Approach 1:
The patent implements a feedback mechanism where the output of the integrator is fed back to the injection-locked oscillator to stabilize its operating point. This negative feedback loop compensates for PVT variations, maintaining stable resonant frequency without requiring complex adjustment circuits. The feedback voltage adjusts the oscillator's control voltage dynamically to counteract frequency drift.
Solution Approach 2:
The patent separates the control of resonant frequency and conversion gain by introducing independent control mechanisms. The resonant frequency is controlled by the injection-locked oscillator's natural frequency (determined by its RC time constant), while the conversion gain is controlled by the integrator's feedback resistance and capacitance. This allows independent adjustment of parameters without affecting each other.
2Adaptability or versatility
If the resonant frequency of the band-pass filter is adjusted, then the filter adapts to different signals, but the conversion gain changes accordingly
Solution Approach 1:
The patent divides the converter into functionally independent segments: the injection-locked oscillator segment for frequency selection and the integrator segment for gain control. The oscillator's resonant frequency is determined by its internal RC network, while the integrator's gain is determined by its feedback RC network. This segmentation allows independent adjustment of frequency and gain without cross-interference.
Solution Approach 2:
The patent introduces dynamic control capabilities where the injection-locked oscillator can be tuned to different frequencies by adjusting its control voltage, and the integrator can independently adjust its gain through feedback parameters. This dynamic independence allows the system to adapt resonant frequency without sacrificing conversion gain stability.
3Device complexity
If voltage-controlled ring oscillators are used, then the circuit is simple, but the frequency drifts with PVT variations
Solution Approach 1:
The patent employs a feedback mechanism where the integrator's output is fed back to the injection-locked oscillator's control input. This creates a self-correcting system that dynamically adjusts the oscillator's frequency to compensate for PVT variations, maintaining stable operation without requiring complex frequency-locking circuits like phase-locked loops.
Solution Approach 2:
The injection-locked oscillator inherently resists frequency deviations through its locking mechanism. When the input signal frequency matches the oscillator's natural frequency, the oscillator automatically locks and maintains stable operation. This self-correcting property reduces the need for external frequency stabilization circuits while maintaining reliability.
4Reliability
If injection-locked oscillators with low-pass filter are used, then PVT drift is reduced, but the quality factor is limited to values less than 0.5
Solution Approach 1:
The patent merges the band-pass filter function with the analog-to-time conversion function in a single integrated circuit. The injection-locked oscillator provides frequency selectivity and PVT stability, while the integrator provides the conversion function and enhances the quality factor through its feedback mechanism. This merging allows achieving Q > 0.5 without sacrificing PVT drift resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution achieves a higher quality factor for the band-pass filter, allows for independent adjustment of the resonant frequency without affecting the conversion gain, and reduces PVT-induced drift, thereby enhancing the converter's performance and reliability.
Implementation Method 1
a first injection-locked oscillator and a first circuit, the first circuit being configured for receiving an output signal of the first oscillator
Implementation Method 2
a feedback loop comprising a second circuit configured for integrating said at least a first pulse signal
Data Source
AI summary
The present disclosure relates to a converter (1) converting a voltage (Vin) into time. The converter comprises a direct path (100) including a first injection-locked oscillator (104) and a first circuit (106). The first circuit is configured for receiving an output signal (Φsens) of the first oscillator and a reference signal (Φ0), and for providing at least a first pulse signal (out) determined by a phase shift between the output signal (Φsens) of the first oscillator and the reference signal (Φ0). The converter further comprises a feedback loop (102) comprising a second circuit (108) configured for integrating said at least one first pulse signal (out).