Page Buffer ADC Using Thermometer-to-Binary Conversion
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Solution Overview
Problem
Existing analog-to-digital conversion devices have large hardware circuit areas and long operating times, making them inefficient for in-memory computing and in-memory searching applications.
Innovation Solution
The proposed analog-to-digital conversion device includes a sensing circuit to generate a thermometer code representing an analog value and a latch logic circuit to convert this code into a binary code, reducing hardware circuit area and operating time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If flash ADC performs parallel input, then conversion speed is improved, but hardware circuit area increases
Solution Approach 1:
The parallel flash ADC structure is segmented into multiple sequential stages. Instead of performing all parallel comparisons simultaneously, the converter divides the conversion process into multiple clock cycles where comparisons are performed in sequences, reducing the need for extensive parallel comparator circuits while maintaining acceptable conversion speed.
Solution Approach 2:
The ADC employs periodic clocked operations to perform conversions in discrete time intervals. The conversion process is broken down into periodic stages where comparators are enabled in sequences during different clock cycles, allowing the same hardware resources to be reused periodically rather than requiring all comparators to operate simultaneously.
2Measurement precision
If TDC performs conversion using flip-flop logical operations, then conversion accuracy is improved, but hardware circuit area increases and operating time lengthens
Solution Approach 1:
The mechanical flip-flop based logical operation system is replaced with a voltage-based comparison system. Instead of using sequential flip-flop logic operations to determine binary bits, the invention uses voltage comparators that directly compare the input voltage against reference voltages, eliminating the need for complex flip-flop logic circuits while maintaining conversion accuracy.
Solution Approach 2:
The conversion mechanism changes from logical state transitions in flip-flops to direct voltage level comparisons. By changing the fundamental parameter from logical operations to voltage threshold comparisons, the system achieves the same binary conversion function with simpler hardware that requires fewer logical stages and less circuit area.
3Measurement precision
If SAR type ADC performs complex output storage and reference voltage generation, then conversion accuracy is improved, but device complexity increases
Solution Approach 1:
The page buffer structure is designed to serve multiple functions simultaneously. It acts as both the output storage register for conversion results and as part of the reference voltage generation system. By making the page buffer multi-functional, the invention eliminates the need for separate dedicated storage and reference voltage generation circuits, thereby reducing overall device complexity while maintaining conversion accuracy.
Solution Approach 2:
The output storage function and reference voltage generation function are merged into a single integrated structure. The page buffer that traditionally only stored output data is now combined with reference voltage generation capabilities, reducing the number of separate components and simplifying the overall ADC architecture while preserving the required conversion precision.
Data Source
AI summary
An analog-to-digital conversion device, includes the following elements. A sensing circuit, coupled to a bit line of a memory array, and used to sense a current in the bit line to generate a bit-sequence, the bit-sequence has a form of a thermometer code to represent an analog value. A latch logic circuit, including a plurality of latches and a plurality of logic circuits to form a page buffer of the memory array, and used to generate a bit-set according to the bit-sequence, the bit-set has a form of a binary code to represent a digital value. The latches and the logic circuits are used to perform a conversion process to convert the bit-sequence into the bit-set, and the conversion process has a bit width.