Ring Oscillator ADC Transition Detection for Better Linearity
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Solution Overview
Problem
Ring oscillator-based analog-to-digital converters (ADCs) face challenges in achieving high linearity across the full range of input voltages, leading to non-linear behavior and loss of resolution, especially at lower input voltage ranges, which complicates the design and increases power consumption.
Innovation Solution
The implementation of a ring oscillator-based ADC with a transition detector that compares outputs of inverters at two consecutive time instances, using a shift in the comparison to enhance linearity, allowing the VCO to operate in a more linear range without the need for complex hardware or software linearization techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a ring oscillator-based ADC is used for analog-to-digital conversion, then the conversion speed and integration capability are improved, but the linearity deteriorates across the full range of input voltages
Solution Approach 1:
The patent applies parameter changes by introducing a shift value to the comparison operation in the transition detector. This shift parameter is adjusted to compensate for the non-linear behavior of the ring oscillator across different input voltage ranges. By dynamically changing the comparison threshold based on the detected transitions, the system maintains linearity while preserving the high-speed conversion capability of the ring oscillator architecture.
2Measurement precision
If complex hardware or software linearization techniques are implemented to improve linearity, then the measurement precision is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent applies local quality by implementing a simple shift mechanism within the transition detector that provides targeted compensation for non-linearity in specific input voltage ranges. Rather than applying complex global linearization techniques across the entire system, the invention introduces a localized adjustment parameter that modifies the comparison operation only where needed, maintaining simplicity while improving linearity in the critical lower input voltage ranges.
3Measurement precision
If complex linearization techniques are used to improve linearity, then the measurement precision is improved, but the power consumption increases
Solution Approach 1:
The patent reduces power consumption by using a simple parameter adjustment (shift value) rather than complex linearization techniques. The shift mechanism modifies the comparison threshold in the transition detector using minimal additional circuitry, avoiding the high power consumption associated with complex digital correction algorithms or additional calibration circuits. This approach maintains linearity improvement while keeping power usage low.
Data Source
AI summary
A ring oscillator-based analog-to-digital converter (ADC). The ring oscillator-based ADC includes a ring oscillator and a transition detector. The ring oscillator may include a set of inverters coupled in a ring wherein an output of an inverter is coupled to an input of a successive inverter in the ring. The transition detector is configured to detect transitions of outputs of the inverters by comparing outputs of two separate inverters at two consecutive time instances. The transition detector may include two sets of registers configured to store outputs of the set of inverters at two consecutive time instances, respectively, and a set of comparators configured to compare the outputs stored in the two sets of registers. Each comparator may be configured to compare an output of one inverter at a first time instance and an output of another inverter at a second time instance.