Correlated Double Sampling in Time-to-Voltage Converters
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Solution Overview
Problem
Existing time-to-voltage converters are susceptible to flicker noise and performance variations due to manufacturing process, temperature, and aging, which affect the accuracy of time interval measurements, especially in applications requiring precise signal conversion.
Innovation Solution
The implementation of a time-to-voltage converter using correlated double sampling techniques, where a bias current is used to generate both the output voltage and a correlated reference voltage, reducing noise and improving gain accuracy by eliminating dependencies on voltage ratios, resistor-capacitor components, and transistor ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional time-to-voltage converter circuits are used, then the basic time measurement function is achieved, but the measurement precision deteriorates due to flicker noise and sensitivity to manufacturing process variations, temperature, and aging
Solution Approach 1:
The patent implements feedback by sampling the bias current at two different times (during the time interval being measured and during a reference interval) and using this sampled information to generate a corrected output. The system feeds back the relationship between the bias current and timing information to compensate for drift and noise, thereby improving measurement precision while maintaining reliability
Solution Approach 2:
The patent changes the temporal parameters of bias current sampling by taking measurements at different time intervals (the measured interval and a reference interval). By varying the timing parameters and comparing results across different intervals, the system eliminates sensitivity to manufacturing variations, temperature, and aging effects
2Device complexity
If current sources with low overdrive voltage are used, then the device complexity is reduced, but object-generated harmful factors increase due to substantial flicker noise
Solution Approach 1:
The system uses feedback to measure and compensate for the flicker noise generated by simple current sources. By sampling the bias current at known intervals and using this information to correct the output, the patent eliminates the harmful noise effect while maintaining the benefit of circuit simplicity
Solution Approach 2:
The patent converts the harmful flicker noise into useful information by sampling it at specific intervals. The noise characteristics become part of the measurement process, allowing the system to distinguish between actual timing variations and noise-induced variations, thereby transforming the harmful factor into a beneficial diagnostic tool
Data Source
AI summary
A time-to-voltage converter is configured to generate an output voltage signal and a correlated reference voltage signal. The time-to-voltage converter includes a current source configured to generate a bias current through a current source output node. The time-to-voltage converter includes a first switched-capacitor circuit coupled to the current source output node and configured to generate the output voltage signal based on an input time signal and the bias current during a first interval. The time-to-voltage converter includes a second switched-capacitor circuit coupled to the current source output node and configured to generate the correlated reference voltage signal based on a reference time signal and the bias current during a second interval. The first interval and the second interval are non-overlapping intervals.