Current-Comparison SAR ADC Circuit Without Capacitor Arrays
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Solution Overview
Problem
Existing AD converters, such as those described in Patent Document 1, face challenges of increased occupation area, power consumption, and reduced operation speed due to the inclusion of a capacitor array and the need for additional circuitry to convert current signals to voltage signals.
Innovation Solution
A semiconductor device incorporating a comparison portion, a first and second digital-analog conversion portion, and a control portion to compare and convert current signals, allowing for a novel successive approximation AD converter with reduced area, power consumption, and improved operation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitor array DA conversion portion is used in the AD converter, then the resolution can be increased, but the occupation area significantly increases
Solution Approach 1:
The invention extracts and eliminates the capacitor array from the DA conversion portion, replacing it with a current source-based approach. This removal of the bulky capacitor array directly reduces the occupation area while maintaining the resolution through alternative current comparison mechanisms
Solution Approach 2:
The invention substitutes the traditional voltage-based DA conversion mechanism (using capacitors) with a current-based mechanism. By using current sources instead of capacitor arrays, the system achieves the same resolution function with significantly reduced area occupation
2Adaptability or versatility
If additional circuitry is added to convert current signals to voltage signals, then the AD converter can handle current inputs, but the device complexity increases
Solution Approach 1:
The invention creates a universal AD converter architecture that can directly handle both voltage and current inputs through the same comparison portion. The comparison circuit is designed to work with current signals natively, eliminating the need for separate voltage conversion circuitry and thereby reducing overall device complexity while maintaining versatility
Solution Approach 2:
Instead of converting current to voltage as in traditional designs, the invention inverts the approach by having the comparison portion directly compare current signals. This inversion of the conversion direction eliminates the need for additional voltage conversion circuitry and simplifies the overall system
3Reliability
If a traditional AD converter architecture is used, then the conversion function is achieved, but the operation speed is reduced
Solution Approach 1:
The invention performs preliminary action by pre-charging the comparison portion and preparing the current sources before the actual conversion cycle begins. This preliminary preparation allows the conversion operation to proceed at full speed without initialization delays, thereby improving operation speed while maintaining reliable conversion function
Solution Approach 2:
The invention implements periodic action through clocked operation cycles that systematically control the comparison and conversion processes. This periodic timing approach ensures reliable conversion function while optimizing the speed through synchronized operation phases and efficient use of clock cycles
Data Source
AI summary
A novel semiconductor device is provided. An analog signal is converted into a digital signal using a comparison portion comparing two current values, a control portion, and a current output digital-analog conversion portion. The control portion has a function of generating a sign bit showing a magnitude relation between the two current values, a function of converting a difference between the two current values into a digital signal by successive approximation, and a function of outputting the sign bit and the digital signal.