Asynchronous SAR ADC Clock Calibration for Accurate N-Bit Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Successive Approximation Register Analog-to-Digital Converters (SAR ADCs) face challenges in implementing an exact clock period for binary searching operations, leading to inaccuracies in converting analog signals to digital data.
Innovation Solution
The proposed solution involves a background calibration scheme that includes a clock generator with fine and coarse tuning circuits, a comparator, and a background calibration circuit to sense and adjust the clock signal's cycle number, ensuring accurate clock periods by controlling the delay time through a control signal, allowing for precise conversion of analog signals to multi-bit digital data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a clock signal is generated inside the asynchronous SAR ADC, then the ADC can operate autonomously without external clock input, but it becomes difficult to implement an exact clock period required for the binary searching operation section
Solution Approach 1:
The patent implements a feedback mechanism where the background calibration circuit senses the actual cycle number of the clock signal used in the comparator and successive approximation logic circuit, compares it with the expected N cycles, and generates a control signal to adjust the delay time of the clock generator. This closed-loop feedback ensures the clock period accuracy is maintained while allowing autonomous operation.
Solution Approach 2:
The ADC performs self-calibration through the background calibration circuit that automatically detects and corrects clock cycle deviations without external intervention. The system uses its own operational data (cycle number sensing) to adjust its parameters (delay time control signal), enabling it to self-correct and maintain precision autonomously.
2Device complexity
If the delay time of the clock signal is not adjusted, then the circuit operation is simple, but the cycle number of the clock signal deviates from the expected N cycles due to process, temperature, or voltage variations
Solution Approach 1:
The patent dynamically adjusts the delay time parameter of the clock signal based on sensed cycle number deviations. The background calibration circuit modifies the delay time control signal to compensate for variations caused by process, temperature, or voltage changes, thereby maintaining reliable and consistent clock cycling despite environmental conditions.
3Manufacturing precision
If background calibration circuit is added to sense and adjust clock cycles, then the clock period accuracy is improved, but the device complexity increases
Solution Approach 1:
The background calibration circuit acts as an intermediary component that bridges the clock generator and the conversion operation section. It senses the actual clock cycles used and mediates by generating appropriate delay time control signals to adjust the clock generator, thereby improving accuracy without requiring fundamental redesign of the core ADC architecture.
Data Source
AI summary
An apparatus includes a sample holding circuit, a comparator, a digital-to-analog converter, a clock generator, a successive approximation logic circuit, and a background calibration circuit. The apparatus converts an analog signal into digital data based on an asynchronous clock signal. The clock signal follows the number of clocks in a converting operation section through a background calibration scheme.