On-Chip ADC Calibration Signal Generation With Tunable Oscillator
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Solution Overview
Problem
Existing time-interleaved analog-to-digital converters (ADCs) face challenges in efficiently generating input signals for calibration due to intrinsic interleaving errors like DC offset, gain, and skew, which require specific frequency and amplitude ranges for fast error detection and calibration convergence, often relying on external systems that incur resource overhead and time constraints.
Innovation Solution
A self-contained system using an oscillator, such as a ring oscillator, generates calibration signals with adjustable frequency and amplitude, enabling efficient ADC calibration without external dependencies, utilizing a driver circuit to provide output signals with precise frequency, amplitude, and timing characteristics, and a controller to manage oscillator calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external calibration systems are used to generate input signals for ADC calibration, then calibration accuracy can be achieved, but resource overhead and time constraints increase
Solution Approach 1:
The system uses an on-chip oscillator to generate calibration signals autonomously, eliminating the need for external calibration equipment. The oscillator is integrated within the ADC chip and can self-generate the required test signals for calibration, making the system self-sufficient and reducing external resource dependencies.
Solution Approach 2:
The oscillator serves multiple functions: it generates calibration signals for ADC calibration, provides clock signals for normal operation, and can be tuned to different frequencies. This multi-functionality reduces the need for separate dedicated calibration equipment, thereby reducing resource overhead while maintaining calibration accuracy.
2Measurement precision
If external calibration systems are used to generate input signals for ADC calibration, then calibration accuracy can be achieved, but chip bring-up time increases
Solution Approach 1:
The oscillator is pre-integrated on the chip and can immediately generate calibration signals upon power-up, eliminating the need to connect external calibration equipment and perform setup procedures. This preliminary preparation of the calibration signal generation capability significantly reduces chip bring-up time.
Solution Approach 2:
The self-contained oscillator enables the ADC to perform calibration autonomously without waiting for external equipment setup, thereby reducing the overall time required for chip bring-up while maintaining calibration accuracy.
3Device complexity
If fixed frequency and amplitude calibration signals are used, then signal generation is simple, but fast error detection and calibration convergence cannot be guaranteed
Solution Approach 1:
The oscillator frequency and amplitude are made dynamically adjustable through control circuits that can tune the oscillator parameters. This allows the calibration signal to adapt its frequency and amplitude based on the specific calibration requirements, enabling faster error detection and calibration convergence while maintaining reasonable signal generation complexity.
Solution Approach 2:
The system changes the frequency and amplitude parameters of the calibration signal dynamically during the calibration process. By adjusting these parameters based on real-time calibration needs, the system achieves faster calibration convergence without excessive complexity in the signal generation mechanism.
Data Source
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AI summary
A device may include an oscillator and a driver. The oscillator may be coupled to circuitry providing calibration of the oscillator. The oscillator may receive from the circuitry a first signal that causes the oscillator to generate a second signal having a first frequency to be used for calibration of an analog-to-digital converter (ADC). The driver may be coupled to the oscillator and the ADC. The driver may receive the second signal from the oscillator. The driver may receive a third signal indicating an amplitude to apply to the second signal. The driver may provide, to the ADC based at least on the second signal and the third signal, an output signal having the first frequency and the amplitude.