Variable Resistor Calibration for Arbitrary Termination Voltage
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Solution Overview
Problem
Conventional semiconductor integrated circuit apparatuses lack the ability to adjust termination resistors at the receive (Rx) side, especially when an arbitrary termination voltage different from the power source voltage is applied, making it difficult to adjust resistance values in transceiver circuits.
Innovation Solution
A resistance adjusting circuit that includes a reference resistor, current sources, and a controller to set the resistance value of a variable resistor such that the voltage at the reference resistor and the variable resistor's terminal are equal, allowing for precise adjustment of resistance values regardless of the termination voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a variable resistor element is grounded in conventional parameter correcting circuits, then the circuit structure is simplified, but it becomes impossible to adjust resistance values when an arbitrary termination voltage different from the power source voltage is applied
Solution Approach 1:
Instead of grounding one terminal of the variable resistor element as in conventional circuits, the patent connects both terminals to functional circuit nodes. Specifically, the first terminal connects to the mirror circuit and the second terminal connects to the receiving circuit side, enabling resistance adjustment under arbitrary termination voltages by inverting the conventional grounding approach
Solution Approach 2:
The patent introduces a mirror circuit as an intermediary between the variable resistor element and the power source. The mirror circuit receives the power source voltage and provides a scaled version to the variable resistor element, enabling precise resistance adjustment while adapting to arbitrary termination voltages without direct grounding
2Device complexity
If no adjusting equipment is provided for termination resistors at the receive side, then the device complexity is reduced, but the measurement precision and control capability of resistance values are insufficient
Solution Approach 1:
The variable resistor element serves multiple functions: it acts as both the adjustment component and the termination resistor at the receiving circuit side. By integrating these functions, the patent achieves precise resistance adjustment capability without adding separate adjusting equipment, thus maintaining device simplicity while improving measurement precision
Solution Approach 2:
The receiving circuit side performs its own resistance adjustment using the variable resistor element controlled by control signals. This self-service mechanism eliminates the need for external adjusting equipment while providing precise resistance value control, reducing device complexity while improving adjustment precision
Data Source
AI summary
A resistance adjusting circuit including, a reference resistor, a first power source configured to output a first voltage, a first current source configured to output a first current based on a reference current set by using the reference resistor, a first variable resistor, a second current source configured to output a second current obtained by multiplying the first current by a reciprocal ratio, the reciprocal ratio being obtained as a reciprocal number of a ratio of a target resistance of the first variable resistor to a resistance of the reference resistor, and a controller configured to set a resistance of the first variable resistor so that a voltage at a second terminal of the reference resistor and a voltage at a connecting part of the first variable resistor and the second current source become equal to each other.