DAC Output Sampling for Time-Interleaved Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current high-speed communication systems face challenges in calibrating time-interleaving DACs due to differences and skews between sub-converters, leading to reduced conversion accuracy and signal quality, with existing calibration methods being costly, complex, and inefficient, particularly requiring special test signals and feedback mechanisms that are not universally supported.
Innovation Solution
A 'virtual' analog-to-digital converter (VADC) is introduced to measure the analog output of a DAC, identifying valid digital samples within a threshold voltage range, allowing for extraction of signal properties like offset, gain, and timing for calibration, thereby reducing the need for costly ADCs on the transmit side and simplifying the calibration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an ADC is used on the transmit side for calibration, then calibration accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The patent uses a virtual ADC that creates a digital copy of the analog signal by sampling and quantizing it, replacing the need for a physical ADC on the transmit side. This virtual representation allows calibration operations to proceed without adding expensive hardware components while maintaining the necessary measurement capabilities
Solution Approach 2:
The patent introduces an intermediary processing stage where the analog signal is converted to digital form through sampling and quantization before calibration. This intermediary digital representation serves as a bridge between the analog DAC output and the digital calibration algorithms, enabling accurate calibration without requiring a high-speed physical ADC
2Measurement precision
If special test signals are used for calibration, then calibration precision is improved, but time consumption and workload increase
Solution Approach 1:
The patent enables the calibration system to use the actual transmitted data signal itself as the calibration source, rather than requiring external test signals. The system extracts calibration information from the normal operational signal, allowing calibration to occur using readily available data without additional signal generation overhead
Solution Approach 2:
The patent performs calibration operations in the background during normal signal processing, preparing calibration data and performing adjustments without interrupting the main signal transmission flow. This preliminary and concurrent processing allows calibration to complete without adding significant time to the overall system operation
3Measurement precision
If feedback mechanisms are used for calibration, then calibration accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a feedback mechanism where calibration information is extracted from the transmitted signal and used to adjust DAC parameters. The system continuously monitors the output signal characteristics and feeds this information back to the calibration controller, enabling accurate adaptive calibration without requiring complex external feedback hardware
Solution Approach 2:
The patent designs a calibration system that can operate with multiple signal types and transmission modes using the same fundamental architecture. The feedback mechanism is universally applicable across different communication standards and signal formats, reducing the need for specialized feedback circuits for each application
4Measurement precision
If high-speed ADCs are used for calibration, then measurement precision is improved, but cost and power consumption increase
Solution Approach 1:
The patent segments the high-speed conversion function into multiple lower-speed sub-converters that operate in parallel or sequence. By dividing the high-speed sampling task into several lower-rate conversions, the system achieves equivalent measurement precision without requiring a single expensive high-speed ADC, thereby reducing overall system cost and power consumption
Data Source
AI summary
A transmitter including a digital-to-analog converter (DAC) to generate an analog output corresponding to a transmitted signal. The transmitter further includes an analog-to-digital converter (ADC) coupled to the DAC. The ADC measures the analog output of the DAC to identify a set of digital samples. The ADC identifies, from the set of digital samples, a set of valid samples, wherein each valid sample has a voltage within a voltage range. The ADC extracts one or more signal properties from the set of valid samples.