Anti-Aliasing TDC Buffer Chain for Accurate Voltage Sensing
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Solution Overview
Problem
Time-to-digital converters face aliasing errors when converting thermometer-encoded data to binary-encoded data, particularly due to multiple pulses being captured within a sampling window, leading to inaccuracies in voltage level measurement.
Innovation Solution
An anti-aliasing time-to-digital converter (TDC) with an N-bit buffer chain is implemented, which detects the earliest failure point of a pulse signal and selectively includes or excludes bits from the buffer chain to generate a sum representing the voltage level, preventing aliasing errors by adjusting the count based on the midpoint of the buffer chain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard time-to-digital converter captures all pulses in the sampling window, then the measurement range is increased, but aliasing errors occur when multiple pulses are captured
Solution Approach 1:
The buffer chain is divided into two segments: a first portion and a second portion. The TDC selectively sums bits from only the first portion when aliasing is detected, effectively segmenting the measurement process to exclude corrupted data from the second portion while retaining valid data from the first portion.
Solution Approach 2:
The system performs preliminary detection of the lowest failure position in the thermometer code before generating the final binary output. By identifying where aliasing occurred and adjusting the summation accordingly, the system preemptively corrects the measurement error rather than attempting to correct it after the fact.
2Productivity
If the TDC counts all 1 bits in the buffer chain, then the conversion is simple and fast, but aliasing errors corrupt the binary code output
Solution Approach 1:
The system performs preliminary detection of the lowest failure position in the thermometer code before generating the final binary output. By identifying where aliasing occurred and adjusting the summation accordingly, the system preemptively corrects the measurement error rather than attempting to correct it after the fact.
Solution Approach 2:
The TDC dynamically adjusts its counting behavior based on the detected failure position. When aliasing is detected in the second portion, the system adaptively changes from counting all bits to counting only bits in the first portion, optimizing both speed and accuracy for each specific measurement condition.
Data Source
AI summary
Systems, apparatuses, and methods for implementing an anti-aliasing technique for a time-to-digital converter are described. A pulse generator generates a pulse with a width that is representative of a voltage level of a supply voltage. A buffer chain receives the pulse from the pulse generator. A first sum is calculated by adding together a number of one bits in a first portion of the buffer chain. Also, a second sum is calculated by adding together a number of one bits in a second portion of the buffer chain. Then, a third sum is calculated by adding the first sum to the second sum if the first sum is saturated. Otherwise, the third sum is equal to the first sum if the first sum is not saturated. The third sum is used as a representation of the voltage level of the supply voltage.