DAC Signal Calibration for Echo and Offset Mismatch
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Solution Overview
Problem
Digital-to-analog conversion apparatuses face challenges with offsets due to current source offsets and mismatch between signals and transmission paths, leading to echo issues that require effective calibration for improved conversion results.
Innovation Solution
A digital-to-analog conversion apparatus with a signal calibration mechanism, comprising a digital-to-analog conversion circuit, an echo transmission circuit, an echo calibration circuit, and a calibration parameter calculating circuit. This setup performs echo-canceling and mismatch echo-canceling, generates calibration signals, and calculates offset values to converge response coefficients and update codeword offset tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital-to-analog conversion is performed using current sources, then conversion capability is achieved, but offset errors are introduced due to current source offset values
Solution Approach 1:
The patent applies preliminary action by performing calibration before actual digital-to-analog conversion. The calibration process pre-determines offset values for each current source and stores them in offset tables. During normal operation, these pre-calibrated offset values are used to compensate for current source errors, ensuring accurate conversion without introducing offset errors in real-time operation.
Solution Approach 2:
The patent implements feedback through an echo path that feeds back the analog output signal to an ADC, converting it back to digital form. This feedback path allows the system to measure the actual output and compare it with the expected output, enabling calculation and correction of offset errors. The feedback mechanism continuously monitors and corrects conversion accuracy.
2Productivity
If signal transmission is performed through transmission paths, then signal delivery is achieved, but mismatch between signal and transmission path causes echo
Solution Approach 1:
The patent extracts the echo component from the feedback signal and processes it separately through an echo cancellation path. The echo signal is isolated from the main signal path and subjected to specific cancellation processing using calibrated offset values, removing the harmful echo effect while preserving the main signal transmission function.
Solution Approach 2:
The patent converts the harmful echo effect into a useful calibration signal. By intentionally analyzing the echo path and measuring the mismatch effects, the system gains information about transmission path characteristics. This information is then used to improve overall system accuracy, turning the previously harmful echo into a beneficial source of calibration data.
3Measurement precision
If calibration circuits are added to cancel echo and offsets, then signal accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing calibration and echo cancellation circuits that serve multiple functions. The same calibration infrastructure is used for both offset compensation and echo cancellation. The feedback path serves dual purposes: monitoring output accuracy and generating calibration data. This multi-functionality reduces the need for separate dedicated circuits for each function.
Solution Approach 2:
The patent merges the calibration process with the echo cancellation process. Instead of implementing separate calibration and echo cancellation systems, the patent combines them into a unified calibration framework where offset calibration and echo path calibration are performed together. This integration reduces overall circuit complexity by sharing common components and processing paths.
Data Source
AI summary
The present invention discloses a digital-to-analog conversion apparatus having signal calibration mechanism is provided. A digital-to-analog conversion circuit includes conversion circuits to generate an output analog signal and echo-canceling analog signals. An echo transmission circuit processes an echo-transmitting path to generate an echo signal. An echo calibration circuit generates an output calibration signal and echo-canceling calibration signals according to an input digital circuit through calibration circuits corresponding to the conversion circuits. A calibration parameter calculating circuit generates a plurality of offsets according to an error signal of the echo signal relative to the calibration signals and path information related to the echo calibration circuit. The echo calibration circuit makes response coefficients converge according to the error signal and pseudo-noise transmission path information from the digital-to-analog conversion circuit to the echo transmission circuit, and updates codeword offset table according to the offset.