SRAM Reference Voltage Generator with Trimmed Stages for Stable Reads
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Solution Overview
Problem
Generating a stable reference voltage with a narrow distribution width is difficult for differential-type sense amplifiers in single bit line-type SRAMs, which affects the stability and accuracy of data reading operations.
Innovation Solution
A reference voltage generator is introduced that includes specific configurations of PMOS and NMOS transistors to generate a stable reference voltage, utilizing a precharge circuit, sense amplifier, and switching circuit to compare bit line and reference bit line voltages, with trimming capabilities to adjust the reference voltage to a desired level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a differential-type sense amplifier is used to determine data stored in a single bit line-type SRAM cell, then the sense amplifier operates stably even with a small input voltage difference, but it is very difficult to generate a stable reference voltage having a narrow distribution width
Solution Approach 1:
The reference voltage generator is divided into multiple transistor stages (first-type transistors connected between power supply and first node, second-type transistors connected between first node and second node, third-type transistors connected between second node and ground). This segmentation allows each stage to contribute to the overall reference voltage stability while maintaining a narrow distribution width through controlled transistor characteristics.
Solution Approach 2:
The patent utilizes different transistor types (PMOS and NMOS) with specific parameter configurations to generate the reference voltage. By selecting appropriate transistor parameters and arranging them in specific configurations, the reference voltage achieves both stability and narrow distribution width, resolving the contradiction between reliability and manufacturing precision.
2Manufacturing precision
If a reference voltage generator using first-type transistors is implemented, then a stable reference voltage with narrow distribution width can be generated, but the device complexity increases
Solution Approach 1:
The reference voltage generator is designed to serve multiple functions: generating a stable reference voltage, providing narrow distribution width, and enabling accurate data reading. By integrating these functions into a unified circuit structure using first-type transistors, the patent avoids the need for separate components, thereby managing device complexity while achieving high manufacturing precision.
Data Source
AI summary
A static random access memory includes a memory cell that stores data, a reference voltage generator that generates a reference voltage, a precharge circuit that is connected with the memory cell through a bit line, is connected with the reference voltage generator through a reference bit line, and pre-charges the bit line and the reference bit line, and a sense amplifier that is connected with the bit line and the reference bit line, compares a voltage of the bit line and a voltage of the reference bit line to generate a comparison result, and determines a value of the data stored in the memory cell based on the comparison result. The reference voltage generator includes first-type transistors.