Replica Input Buffer Threshold Control for Stable Signal Sensing
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Solution Overview
Problem
Semiconductor devices face challenges in accurately sensing input signals due to shifts in logic threshold voltage caused by process variations and temperature changes, especially when the difference between high and low potential input signals decreases, leading to inaccurate sensing and issues with external clock frequency changes.
Innovation Solution
The semiconductor device incorporates a first input buffer, a replica circuit with the same configuration, a reference voltage generating circuit, and a comparator circuit to adjust the logic threshold voltage by generating a threshold adjustment signal, ensuring accurate sensing of input signals without relying on external clock signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the logic threshold voltage is set to a specified value intermediate between VIH and VIL, then the input circuit can sense H and L levels, but the sensing accuracy deteriorates when the logic threshold voltage shifts due to process variation or temperature change
Solution Approach 1:
The patent creates a replica circuit that duplicates the input buffer configuration. The replica circuit generates a threshold voltage that is fed back to the input buffer, allowing the system to compensate for threshold shifts without requiring external calibration. This copying approach enables the main circuit to maintain accurate sensing by referencing the replica's threshold characteristics.
Solution Approach 2:
The patent implements a feedback mechanism where the threshold voltage generated by the replica circuit is fed back to the input buffer. This feedback loop continuously adjusts the threshold voltage to compensate for shifts caused by process variation or temperature changes, maintaining stable and accurate input signal sensing throughout device operation.
2Use of energy by stationary object
If the difference between VIH and VIL decreases due to lower operating voltage, then power consumption is reduced, but the input circuit cannot accurately sense the input signal levels
Solution Approach 1:
The patent dynamically adjusts the logic threshold voltage parameter based on the actual operating conditions. By changing the threshold voltage to match the reduced voltage swing between VIH and VIL, the system maintains accurate sensing capability even when operating at lower power supply voltages. The threshold voltage is no longer fixed but adapts to the operating voltage level.
3Adaptability or versatility
If a ring oscillator is used to adjust the logic threshold voltage, then the threshold can be adjusted in correspondence with input signal levels, but the adjustment process becomes more complex
Solution Approach 1:
The patent replaces the complex ring oscillator-based adjustment mechanism with a simpler replica circuit approach. The replica circuit, being identical to the input buffer, naturally generates the appropriate threshold voltage without requiring additional oscillation circuits or complex control logic. This copying strategy achieves adaptability while reducing overall device complexity.
Data Source
AI summary
A semiconductor device includes a first input buffer adjusting a logic threshold voltage, a first replica circuit, a first reference voltage generating circuit, and a first comparator circuit. The first replica circuit is identical in circuit configuration to the first input buffer. The first replica circuit has an input and an output connected to the input. The first replica circuit generates the logic threshold voltage as an output voltage. The first reference voltage generating circuit generates a first reference voltage. The first comparator circuit compares the logic threshold voltage as an output voltage of the first replica circuit to the first reference voltage to generate a first threshold adjustment signal. The first comparator circuit supplies the first threshold adjustment signal to the first input buffer and the first replica circuit. The first threshold adjustment signal allows the first input buffer to adjust the logic threshold voltage.