Current-Steering DAC Cell Switching With Intermediate Dump State
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Solution Overview
Problem
Current steering digital-to-analog converters (DACs) are prone to nonlinear distortion due to non-ideal error signals generated during code changes, which are not effectively mitigated by standard implementations, leading to switching-related errors.
Innovation Solution
The implementation of additional 'dump' states in DAC cells, allowing for intermediate discharging or pre-charging of internal capacitance before polarity changes, and the use of redundant DAC cells to apply switching techniques that minimize dynamic charge errors by incorporating an intermediate 'dump' state before switching between binary output states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If current cells switch output states directly in response to digital input code changes, then the DAC responds quickly to input changes, but non-ideal error signals are generated during switching transitions causing nonlinear distortion
Solution Approach 1:
The patent applies preliminary action by introducing an intermediate 'dump' state that is activated before the actual polarity switching occurs. This dump state pre-charges or pre-discharges internal capacitance, preparing the current cell for the upcoming transition and minimizing the generation of error signals during the switching process, thereby reducing nonlinear distortion while maintaining fast response
2Adaptability or versatility
If multiple current cells are used to implement current-steering DAC, then the DAC can provide variable current output, but switch injection errors and asymmetries in ON/OFF transitions generate non-ideal error signals
Solution Approach 1:
The patent introduces an intermediary 'dump' state that acts as a mediator between the ON and OFF states of current cells. This intermediate state provides a controlled transition path that reduces switch injection errors and asymmetries by allowing internal capacitance to be properly charged or discharged before the switching event, thereby minimizing harmful switching errors while preserving variable current output capability
3Adaptability or versatility
If the number of current cells switching during transition depends on input code sequence, then the DAC operates flexibly, but nonlinear distortion results from switching-related non-ideal effects
Solution Approach 1:
The patent applies preliminary action by activating the dump state before polarity switching based on the input code sequence. This pre-conditioning of internal capacitance through the dump state ensures that switching-related non-ideal effects are minimized regardless of which current cells are switching, thereby maintaining linearity and reducing nonlinear distortion while preserving input code flexibility
Data Source
AI summary
Representative implementations of devices and techniques provide digital-to-analog conversion of signals while minimizing switching related errors. Digital to analog converter (DAC) cells may be arranged to include one or more operating states in addition to binary output states, and may employ a switching technique to “dump” the DAC cell between binary outputs. Further, an array of DAC cells may include a partial set of redundant DAC cells for implementation of the switching technique.