DAC Signal Calibration Using Echo-Canceling Offset Mapping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current digital-to-analog conversion (DAC) circuits suffer from manufacturing process offsets, resulting in non-ideal amplitude and shape of output analog signals, which significantly affect system performance.
Innovation Solution
A digital-to-analog conversion apparatus and method incorporating a DAC circuit, echo transmission circuit, calibration circuit, echo-canceling circuit, error calculating circuit, inverted error calculating circuit, and offset updating circuit to perform signal calibration by updating codeword offsets in a mapping table based on echo-canceling coefficients and path delay, thereby correcting signal offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a current-output type DAC circuit is used, then the circuit can generate analog signals with different intensities based on digital codes, but manufacturing process offset results in non-ideal offsets of amplitude and shape of the outputted analog signal
Solution Approach 1:
The patent performs preliminary calibration by measuring the actual output signals for all digital codes and pre-calculating compensation values stored in a lookup table. During normal operation, the system retrieves and applies the appropriate compensation value based on the input digital code, eliminating the need for real-time complex calculations and ensuring consistent offset correction.
Solution Approach 2:
The system implements feedback by measuring the actual output analog signal, comparing it with the expected signal, calculating the offset error, and using this error information to update the compensation values in the lookup table. This closed-loop feedback mechanism continuously optimizes the offset correction to maintain high precision.
2Measurement precision
If offset calibration is performed to correct manufacturing process offsets, then signal accuracy is improved, but additional calibration circuits and processing steps are required
Solution Approach 1:
The patent introduces a lookup table as an intermediary component that stores pre-calculated compensation values. Instead of implementing complex real-time offset calculation circuits, the system uses this intermediate storage structure to map digital codes to their corresponding compensation values, simplifying the overall circuit architecture while maintaining calibration effectiveness.
Solution Approach 2:
The system creates a digital copy of the offset error characteristics by measuring and storing compensation values in a lookup table. This digital representation allows the system to correct analog signal offsets using digital processing, avoiding the need for complex analog correction circuits and enabling precise offset compensation through software-based methods.
Data Source
AI summary
The present invention discloses a DAC method having signal calibration mechanism is provided. Operation states of current sources are controlled to generate an output analog signal by a DAC circuit according to a codeword of an input digital signal. An echo signal is generated by an echo transmission circuit according to the output analog signal. The codeword is mapped to generate an offset signal by a calibration circuit according to a codeword offset mapping table. The offset signal is processed to generate an echo-canceling signal by an echo-canceling circuit. By a calibration parameter calculation circuit, offset amounts are generated according to a difference between the echo signal and the echo-canceling signal, the offset amounts are grouped to perform statistic operation according to the operation states and current offset values are calculated according to calculation among groups and converted to codeword offset values to update the codeword offset mapping table.