DAC Switch Control for Glitch and Power Reduction
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Solution Overview
Problem
Digital-to-analog converters (DACs) experience significant switching activity, leading to power consumption, glitching, and crosstalk issues, particularly during code transitions, which negatively impact performance and efficiency.
Innovation Solution
Implementing a partial DAC data ignore switching mode, where a control circuit compares first and second digital data and operates analog switches only when the decoded states differ, reducing unnecessary switching and minimizing power consumption and glitching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DAC operates with full switching activity for all digital input changes, then conversion accuracy is maintained, but power consumption increases and glitching occurs
Solution Approach 1:
The patent applies partial action by implementing a data ignore mode where the DAC selectively ignores certain digital input changes that would not affect the analog output. The control circuit compares consecutive digital input codes and determines when changes occur in bits that do not impact the analog output, thereby preventing unnecessary switching operations and reducing power consumption while maintaining conversion accuracy for significant changes.
2Speed
If DAC switches operate frequently for every digital code transition, then real-time conversion is achieved, but glitching and crosstalk increase
Solution Approach 1:
The control circuit implements partial action by performing selective switching only when digital input changes actually affect the analog output. The comparison logic identifies when code transitions occur in insignificant bits and suppresses corresponding switch operations, thereby eliminating glitching and crosstalk while maintaining real-time conversion capability for meaningful changes.
3Reliability
If all analog switches are operated for every digital input change, then complete signal update is ensured, but unnecessary switching causes power waste
Solution Approach 1:
The patent applies partial action through the data ignore mode that selectively updates only those analog switches corresponding to significant digital input changes. The control circuit compares consecutive codes and identifies which bits represent meaningful changes, activating switches only for those bits while ignoring changes in insignificant bits, thereby ensuring complete signal update for relevant data while eliminating power waste from unnecessary switching.
4Measurement precision
If DAC processes every digital input code transition, then conversion fidelity is maintained, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the digital input code into significant and insignificant bits based on the DAC's resolution and output requirements. The control circuit is segmented into comparison logic that identifies which bits require switching operations, thereby maintaining conversion fidelity for significant bits while simplifying the overall control structure by eliminating unnecessary processing of insignificant bits.
Data Source
Figure 1~2
Figure 3
Figure 4A
AI summary
A digital technique to reduce or minimize switching in a DAC by using a partial DAC data ignore switching mode. In the partial DAC data ignore switching mode, a control circuit compares first and second data, such a first and second digital words, and operates corresponding switches only when the first data differ from the second data. The techniques are applicable to many types of DACs, including voltage output DACs, current output DACs, variable resistance DACs, digital rheostats, digital potentiometers, digiPOTs.