Terminal Correction Circuit for PVT-Stable Resistance and Voltage
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Solution Overview
Problem
In high-speed transmission interfaces, manufacturing process variations, voltage, and temperature fluctuations (PVT variation) affect terminal resistance and voltage, leading to deviations from predetermined values, which can distort transmission signals.
Innovation Solution
A two-stage offset correction circuit comprising a first terminal replica model, terminal voltage offset correction circuit, and terminal resistance offset correction circuit, which adjust resistance ratios and voltages to maintain accurate terminal resistance and voltage values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage correction mechanism is used to offset terminal resistance, then the correction complexity is reduced, but the terminal voltage value still offsets from the predetermined voltage value when transmission resistances do not match
Solution Approach 1:
The correction mechanism is divided into two independent stages: a first correction circuit that adjusts terminal resistance using a first adjustable resistor, and a second correction circuit that adjusts terminal voltage using a second adjustable resistor. This segmentation allows each stage to independently correct its specific parameter without interfering with the other, thereby achieving both resistance and voltage accuracy while maintaining manageable complexity.
2Reliability
If terminal resistance is adjusted to compensate for PVT variation, then resistance matching is improved, but terminal voltage deviates from the predetermined value
Solution Approach 1:
The correction system is segmented into two independent functional blocks: the first correction circuit dedicated to resistance adjustment and the second correction circuit dedicated to voltage adjustment. This allows resistance matching to be optimized independently of voltage level, eliminating the trade-off between these two parameters and enabling both to achieve their optimal values simultaneously.
Solution Approach 2:
The correction circuits employ adjustable resistors that can dynamically adapt their resistance values based on detected deviations. The first adjustable resistor dynamically compensates for resistance mismatches, while the second adjustable resistor dynamically adjusts voltage levels, allowing the system to maintain optimal performance under varying operating conditions.
Data Source
AI summary
A terminal correction circuit includes a first terminal replica model, a terminal voltage offset correction circuit, a second terminal replica model and a terminal resistance offset correction circuit. The first terminal replica model sets a resistance ratio of first and second adjustable resistors according to a voltage correction code, thereby adjusting a terminal voltage. The terminal voltage offset correction circuit compares the terminal voltage and a third power supply voltage and provides the voltage correction code according to the comparison result. The second terminal replica model sets a resistance ratio of third and fourth adjustable resistors according to the voltage correction code and reduces an equivalent resistance value between a half-voltage terminal and a ground voltage according to a resistance correction code. The terminal resistance offset correction circuit compares a comparison voltage with a second power supply voltage and provides the resistance correction code according to the comparison result.