Memory Reference DAC Circuit for Temperature-Stable Read Voltages
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Solution Overview
Problem
Existing semiconductor devices face challenges in accurately adjusting the voltage levels for data read and write operations in memory systems, particularly as the number of bits stored in each memory cell increases, leading to fluctuations in threshold voltage distributions and temperature-dependent variations.
Innovation Solution
The semiconductor device incorporates a digital-analog conversion circuit with a resistor string and switches, where a current source circuit controls the flow of current through a series of resistors, allowing for precise adjustment of output voltage based on digital codes generated by a sequencer, thereby compensating for temperature variations and improving voltage accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of bits stored in each memory cell is increased, then the storage capacity is improved, but the threshold voltage distribution becomes more fluctuating and difficult to control
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the reference voltage levels based on temperature conditions. The reference voltage generation circuit modifies voltage parameters to compensate for threshold voltage fluctuations in multi-bit memory cells, ensuring stable read operations across different temperatures and storage capacities.
2Reliability
If temperature compensation is implemented to improve voltage accuracy, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent introduces an intermediary reference voltage generation circuit that mediates between the temperature variations and the memory read operations. This intermediary circuit generates temperature-compensated reference voltages without requiring complex modifications to the core memory structure, thus improving voltage accuracy while limiting complexity increase.
3Measurement precision
If a digital-analog conversion circuit with current source is used to improve voltage accuracy, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements dynamics by using a current source that can dynamically adjust its output based on temperature conditions and digital input codes. This dynamic current source drives the resistor string to produce accurate analog reference voltages, improving measurement precision while using a relatively simple configurable architecture compared to static high-precision voltage references.
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 configuration ensures monotonicity in DA conversion, reduces output impedance variations, and maintains high accuracy in differential non-linearity, even with variations in resistor values, thus enhancing the overall performance and reliability of the semiconductor device.
Implementation Method 1
an operational amplifier including a first input terminal, a second input terminal, and an output terminal, the operational amplifier that outputs a first voltage from the output terminal
Implementation Method 2
a current source circuit connected between a second node and a third node, wherein a switch out of the plurality of switches is turned on based on the digital code, and the current source circuit causes a first current to flow from a part or all of the plurality of second resistors to the third node via the switch in an on state
Implementation Method 3
a plurality of second resistors including one end connected to the first input terminal, the plurality of second resistors connected in series
Data Source
AI summary
According to one embodiment, a device includes: an operational amplifier including first and second input terminals and an output terminal, the operational amplifier that outputs a voltage; a first resistor including one end connected to the first input terminal and an other end connected to the output terminal; second resistors including one end connected to the first input terminal, the second resistors connected in series; switches each including one end connected to a first node between two adjacent resistors of the second resistors and an other end connected to a second node, the switches that receives a code; and a current source between the second node and a third node. A switch of the switches is turned on based on the code. The current source causes a current to flow from a part or all of the second resistors to the third node via the switch.