LVDS Transceiver Dynamic Impedance Matching
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Solution Overview
Problem
Conventional signaling transceivers face issues with resistance variations due to packaging processes and design complexity, leading to impedance mismatch and reduced operational frequency during high-speed data transmission.
Innovation Solution
The proposed low voltage differential signaling transceiver includes a transmitter with a switchable source resistance and a receiver with a variable load resistance, allowing for impedance matching by adjusting the termination resistor magnitude and adding an additional path to minimize voltage drop, thereby controlling the input signal voltage to maintain consistent output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional signaling transceivers are used with fixed termination resistors, then the design is simple, but impedance mismatch occurs due to packaging resistance variations
Solution Approach 1:
The patent implements dynamic adjustment of termination resistance by introducing a switchable resistor network that can change its resistance value based on detected packaging resistance variations. The receiver includes multiple resistors (R1, R2, R3, R4) that can be selectively connected or disconnected through switches, allowing the termination resistance to be dynamically adjusted to match the actual transmission line impedance despite packaging variations.
Solution Approach 2:
The patent employs a feedback mechanism where the receiver detects the actual packaging resistance value and uses this information to adjust the termination resistance accordingly. The receiver measures the voltage divider ratio created by the packaging resistance and adjusts the switchable resistor network to compensate for detected variations, ensuring optimal impedance matching is maintained.
2Reliability
If serial termination is used to reduce signal reflection, then signal reflection is reduced, but the transceiver operational frequency decreases
Solution Approach 1:
The patent changes the resistance parameter dynamically rather than using a fixed serial termination resistor. By adjusting the termination resistance to match the actual transmission line impedance (accounting for packaging variations), the system achieves optimal signal reflection control without the frequency limitations imposed by fixed serial termination configurations.
Solution Approach 2:
Instead of using a simple serial resistor copy of conventional termination, the patent implements a more sophisticated switchable resistor network that replicates the ideal termination behavior across multiple resistance values, allowing the system to adapt to different packaging conditions while maintaining high-speed operation.
3Reliability
If parallel termination is used to reduce signal reflection, then signal reflection is reduced, but design complexity increases
Solution Approach 1:
The patent segments the termination resistance into multiple discrete resistors (R1, R2, R3, R4) that can be independently controlled. This segmentation allows the system to achieve variable termination without requiring a single complex high-precision resistor, simplifying the overall design while maintaining the ability to adjust to different packaging resistance conditions.
Data Source
AI summary
A low voltage differential signaling transceiver includes a transmitter and a receiver, the transmitter having a first terminal in signal communication with a transmission line, a source resistance in signal communication with the first terminal, a switch in signal communication with the source resistance and in switchable signal communication from ground or an input voltage, a voltage regulator in switchable signal communication with the switch for providing the input voltage to the switch, and a voltage controller in signal communication between the first terminal and the voltage regulator for controlling the input voltage to provide a controlled voltage to a receiver; and the receiver having an amplifier having a first input, a first pad in signal communication with the first input, a load resistance, and a second pad in signal communication with the load resistance, where the first and second pads are both in signal communication with one end of a first transmission line.