Signal Potential Conversion Circuit Termination Jitter Control
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Solution Overview
Problem
Signal electric potential conversion circuits using AC coupling suffer from jitter issues due to potential attenuation at the termination node, especially during high-speed operations, as the signal transition waveform's gradient affects the timing of signal crossing the reference potential, leading to pulse width discrepancies and data pattern-dependent jitter.
Innovation Solution
A signal electric potential conversion circuit with a termination circuit comprising a NMOS transistor and a PMOS transistor, where the NMOS transistor reduces impedance when the termination node potential is lower than a first potential and the PMOS transistor reduces impedance when the potential is higher than a second potential, maintaining the potential within a defined range and preventing attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If AC coupling is used for signal transmission, then high-speed signal transmission is enabled, but jitter occurs due to potential attenuation at the termination node
Solution Approach 1:
The termination circuit dynamically adjusts the impedance of connection elements based on the potential at the termination node. When potential drops below a first threshold, the first connection element's impedance decreases to pull the potential up. When potential exceeds a second threshold, the second connection element's impedance decreases to pull the potential down. This dynamic adjustment prevents potential attenuation and maintains signal stability during high-speed transmission.
Solution Approach 2:
The termination circuit implements feedback control by monitoring the potential at the termination node and automatically adjusting the impedance of connection elements in response. The circuit detects potential deviations from the desired range and corrects them by reducing impedance of appropriate connection elements, creating a closed-loop control system that eliminates jitter without requiring external intervention.
2Reliability
If the termination resistor attenuates the input potential difference, then the amplifier offset compensates, but pulse width distortion occurs causing jitter
Solution Approach 1:
The termination circuit performs preliminary action by proactively maintaining the potential at the termination node within a predetermined range before signal transmission issues can occur. By continuously monitoring and adjusting the impedance of connection elements, the circuit prevents potential attenuation and pulse width distortion before they affect the output signal, ensuring both data accuracy and pulse width precision.
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 that the potential of the termination node is maintained within a predetermined range, thereby preventing jitter in the converted signal, even at high speeds, and maintains the original data width and amplitude of the input signal, enhancing the reliability of signal conversion.
Implementation Method 1
an impedance of the first connection element is reduced when the potential of the termination node is lower than a first potential higher than the power supply voltage of the second power supply
Implementation Method 2
an impedance of the second connection element is reduced when the potential of the termination node is higher than a second potential which is lower than the power supply voltage of the first power supply and which is higher than the first potential
Data Source
AI summary
In a signal electric potential conversion circuit, a capacitor has one end receiving an input signal CIN, and the other end connected to a termination node N1. A conversion circuit receives a potential IN of the termination node N1. A connection element is provided between a power supply VDDH and the termination node N1, and an impedance of the connection element is reduced when the potential IN is lower than a first potential. Another connection element is provided between the termination node N1 and a ground power supply, and an impedance of the connection element is reduced when the potential IN is higher than a second potential.