Floating-Gate Reference Circuit for Wide-Range Temperature Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing analog circuitry with programmable floating-gate transistors faces significant temperature sensitivity issues due to the lack of effective temperature compensation, especially when parameter floating-gate transistors have differing programmed charges, leading to unacceptable variations in output current across a wide range of applications.
Innovation Solution
Implementing multiple temperature-compensated control lines and reference floating-gate transistors with different operating ranges, allowing each parameter floating-gate transistor to connect to the closest reference current, and using cascode arrangements and buffers to minimize temperature dependence, along with dynamic control of word lines in compute-in-memory arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reference floating-gate transistor is used to generate temperature-dependent bias voltage, then the reference circuit is simple, but parameter floating-gate transistors with substantially different output currents from the reference current exhibit high temperature sensitivity
Solution Approach 1:
The patent divides the single reference circuit into multiple reference floating-gate transistors, each programmed with different charges to generate different reference currents. This segmentation allows each reference transistor to effectively compensate for parameter transistors operating in specific current ranges, thereby reducing temperature sensitivity across the full range of output currents while maintaining overall system simplicity.
2Reliability
If multiple reference floating-gate transistors with different operating ranges are implemented, then temperature sensitivity is reduced across wide current ranges, but device complexity and area increase
Solution Approach 1:
The patent designs reference floating-gate transistors that serve multiple functions: they act as both temperature compensation references and programmable current sources. Each reference transistor is diode-connected and can be programmed with specific charges to cover different current ranges, allowing a small set of references (e.g., 4-8 transistors) to provide universal temperature compensation for thousands of parameter transistors across many orders of magnitude of current values.
3Adaptability or versatility
If parameter floating-gate transistors are programmed to cover many orders of magnitude of current values, then application versatility is improved, but temperature sensitivity increases
Solution Approach 1:
The patent changes the charge parameter of reference floating-gate transistors to create a set of reference currents spanning multiple orders of magnitude. By programming reference transistors with geometrically spaced charges (e.g., 1nA, 10nA, 100nA, 1uA), the system achieves wide-range adaptability while maintaining temperature insensitivity through appropriate matching between parameter transistor currents and the nearest reference current.
4Reliability
If dedicated temperature-independent current references are provided for every parameter transistor, then temperature compensation is optimal, but area and power consumption become prohibitive
Solution Approach 1:
The patent merges the reference function with the parameter transistor structure by using the same floating-gate transistor technology for both references and parameters. Multiple reference transistors share common current sinks and control logic, and parameter transistors are grouped to share nearest reference transistors, thereby achieving optimal temperature compensation with minimal area overhead (typically less than 1% of total chip area).
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 significantly reduces temperature sensitivity across a wide range of current values, enabling accurate and efficient temperature compensation for programmable circuit elements, improving performance in reconfigurable analog systems by ensuring temperature-insensitive current sources.
Implementation Method 1
If the current sink is temperature-independent, the control-gate/drain voltage of the reference floating-gate varies linearly with temperature. This node voltage may be applied to a control gate of a parameter floating-gate transistor
Implementation Method 2
Adding or removing charge to the transistor's isolated floating gate node allows for direct control of the transistor's drain current across many orders of magnitude
Implementation Method 3
using cascode arrangements and buffers to minimize temperature dependence
Data Source
AI summary
According to some embodiments, re-programmable and/or reconfigurable analog circuitry may be provided. A plurality of reference floating-gate transistors are each programmable to be connectable to a plurality of global reference control lines of the analog circuitry to facilitate temperature compensation. In some embodiments, the plurality of analog nonvolatile memory cells are associated with parameter floating-gate transistors. Moreover, the plurality of analog parameter nonvolatile memory cells may be programmed to several orders of parameter magnitude.