Multi-DAC Timing Synchronization for Charge Leak Reduction
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Solution Overview
Problem
Existing semiconductor integrated circuits with multiple DA converters face challenges in improving conversion accuracy while maintaining a small circuit area, particularly when DA converters are arranged at narrow intervals.
Innovation Solution
The semiconductor integrated circuit incorporates a global circuit that synchronizes the end timings of the charge storage period across multiple DA converters, reducing charge leak and improving conversion accuracy. Each DA converter includes a current source, capacitive element, amplifier circuit, and switch elements controlled by a control circuit to manage charge storage and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If DA converters are arranged at narrow intervals to reduce circuit area, then the area of the semiconductor integrated circuit is reduced, but charge leak increases and conversion accuracy deteriorates
Solution Approach 1:
The control circuit preliminarily sets the second switch element to an on state before the charge storage period begins, ensuring that the capacitive element is properly connected to the reference potential. This preliminary preparation prevents charge leak during the charge storage period, thereby maintaining conversion accuracy even when DA converters are arranged at narrow intervals with limited spacing.
Solution Approach 2:
The control circuit monitors the operation state of each DA converter and dynamically adjusts the switching timing of the second switch element. By providing feedback control on the charge storage period and synchronizing end timings across multiple DA converters, the system compensates for charge leak effects and maintains consistent conversion accuracy throughout the circuit.
2Measurement precision
If the charge storage period is extended to improve conversion accuracy, then conversion accuracy improves, but the time required for DA conversion increases
Solution Approach 1:
The control circuit implements periodic switching of the second switch element, turning it on before the charge storage period and turning it off at the end of the charge storage period. This periodic action ensures that charge leak is minimized during the charge storage period while maintaining a compact conversion time cycle, thus improving conversion accuracy without significantly increasing the overall conversion time.
Solution Approach 2:
The system dynamically adjusts the duration and timing of the charge storage period based on operational requirements. The control circuit optimizes the charge storage period length to achieve sufficient conversion accuracy while minimizing the time consumed, adapting the charge storage duration to balance accuracy and speed requirements.
3Measurement precision
If synchronization of end timings is implemented across multiple DA converters, then conversion accuracy improves, but device complexity increases
Solution Approach 1:
The control circuits of multiple DA converters are merged into a unified control system that synchronizes the end timings of charge storage periods across all DA converters. By combining control functions and sharing synchronization signals, the system achieves consistent conversion accuracy across multiple converters while avoiding the complexity of completely independent control circuits for each converter.
Solution Approach 2:
The control circuit is designed with multi-functionality to handle both individual DA converter control and synchronized operation across multiple converters. This universal control approach allows the same control logic to manage charge storage periods, switching timing, and synchronization, thereby reducing overall device complexity compared to having separate specialized control circuits for each function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces errors caused by charge leak, enhances the accuracy of DA conversion, and minimizes variations in conversion errors across the semiconductor integrated circuit, thereby improving overall system performance.
Implementation Method 1
Each of the plurality of DA converters includes a current source, a capacitive element, an amplifier circuit, a first switch element, a second switch element, a third switch element, and a control circuit
Implementation Method 2
the amplifier circuit has an input node... maintains the first switch element in an on state while maintaining the second switch element and the third switch element both in an off state in a second period after the first period
Data Source
AI summary
According to one embodiment, in a semiconductor integrated circuit, a second switch has a first end connected to a first end of a capacitive element and a second end connected to a node of a reference potential. A third switch has a first end connected to the first end of the capacitive element and a second end connected to an input node of an amplifier circuit. A control circuit maintains the second switch in an on state while maintaining a first and the third switches in an off state in a first period and maintains the first switch in an on state while maintaining the second and third switches in an off state in a second period after the first period. End timings of the second period in the plurality of DA converters are synchronized with each other in response to a signal from a global circuit.