Time-Interleaved Current DAC Calibration for Mismatch Errors
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Solution Overview
Problem
Time-interleaved current-based DAC architectures face issues with mismatch-induced errors in gain, offset, and timing, leading to reduced accuracy and increased power consumption.
Innovation Solution
Implementing adaptive DAC cells with dual clock signals and error correction circuitry to dynamically calibrate gain and offset mismatches, combined with differential cell structures to reduce noise sensitivity and hysteresis, and incorporating output dump circuitry to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple DACs operate in time-interleaved fashion to reduce power consumption, then power efficiency improves, but mismatch-induced errors in gain, offset, and timing increase
Solution Approach 1:
The patent implements feedback mechanisms through calibration circuits that continuously monitor and correct gain and offset mismatches between parallel DACs. Error detection circuits measure the actual output of each DAC cell and feed correction signals back to adjust the digital input signals, ensuring that mismatches do not degrade overall accuracy despite the time-interleaved operation reducing power consumption.
Solution Approach 2:
The patent dynamically adjusts operational parameters including gain factors, offset values, and timing skew compensation parameters for each DAC cell based on measured performance characteristics. By changing these parameters adaptively through calibration routines, the system maintains high accuracy across varying operating conditions while preserving the power-saving benefits of time-interleaved architecture.
2Productivity
If multiple DACs operate in time-interleaved fashion to enable higher data link speeds, then sampling rate improves, but mismatch-induced errors in gain, offset, and timing increase
Solution Approach 1:
The calibration system continuously monitors output accuracy and feeds correction signals back to each DAC cell to compensate for gain and offset mismatches that become more pronounced at higher sampling rates. This real-time feedback ensures that the increased productivity from parallel operation does not compromise measurement precision.
Solution Approach 2:
The patent performs preliminary calibration of gain and offset parameters before high-speed operation begins, and maintains correction tables that pre-compensate for expected mismatches. This preliminary action ensures that when multiple DACs operate in time-interleaved mode at high sampling rates, the accuracy is preserved through pre-established correction factors.
3Measurement precision
If calibration circuits are added to correct gain and offset mismatches, then accuracy improves, but device complexity increases
Solution Approach 1:
The patent divides the calibration function into separate modular circuits: gain calibration circuits, offset calibration circuits, and timing skew compensation circuits. Each module handles a specific aspect of mismatch correction independently, making the overall calibration system more manageable and easier to implement without excessively increasing device complexity.
Solution Approach 2:
The calibration circuits are designed to handle multiple types of mismatches (gain, offset, timing) using a unified correction framework. The same basic calibration architecture can correct different error types by adjusting specific parameters, reducing the need for separate dedicated circuits for each mismatch type and thereby limiting the increase in device complexity.
4Use of energy by moving object
If parallel DAC cells are used in time-interleaved fashion, then power consumption reduces, but timing skew between cells increases
Solution Approach 1:
The patent introduces timing skew compensation parameters that are adjusted for each DAC cell based on its position in the time-interleaved sequence. By dynamically changing the timing parameters of clock signals or data sampling points for each parallel cell, the system compensates for propagation delays and alignment differences, maintaining timing precision despite the power-efficient parallel architecture.
Data Source
AI summary
A time-interleaved current-based digital-to-analog converter (current DAC) cell includes first input circuitry configured to receive a digital input signal, a first biasing voltage, a first clock, and a second clock. The first clock and the second clock having a phase offset from one another and having a common period. The current DAC also includes a first gate configured to, responsive to an ‘ON’ state of the first clock, pass the digital input signal to a second gate, the second gate being configured to, responsive to an ‘OFF’ state of the second clock, output a first DAC cell activation signal. The current DAC further includes first output circuitry configured to, responsive to the first DAC cell activation signal, output a first analog current signal based on (i) the digital input signal and (ii) the first biasing voltage.