Connecting Circuit Topology for DC-Free Termination in Interfaces
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Solution Overview
Problem
The presence of a DC current flowing through the transmission line and terminating load due to the series connection of the data source and terminating load in conventional connection forms leads to increased power consumption and disconnection of the transmission line, especially when chip capacitors for DC block are not feasible due to limited package substrate area.
Innovation Solution
A connecting circuit with an initial voltage value holding unit and terminating load, which sets both ends of the terminating load at the same potential by applying an initial voltage value when no data signal is input, thereby preventing DC current flow without the need for a chip capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a chip capacitor is inserted to block DC current, then DC current flow is prevented and bias voltage stability is improved, but device area increases and mounting density decreases
Solution Approach 1:
The invention extracts the DC blocking function from the physical chip capacitor and implements it through a control circuit that generates a blocking signal to prevent DC current flow. This removes the need for large capacitive components on the package substrate while maintaining the essential DC blocking capability.
Solution Approach 2:
The invention introduces a control circuit as an intermediary between the data source and transmission interface. This control circuit generates a blocking signal that mediates the DC current flow, allowing DC blocking without direct capacitive coupling and enabling compact substrate design.
2Use of energy by moving object
If the terminating load resistance is reduced to lower power consumption, then power efficiency improves, but DC current flow increases causing transmission line disconnection
Solution Approach 1:
The invention applies preliminary anti-action by generating a blocking signal before DC current can flow through the transmission line. The control circuit proactively prevents DC current accumulation that would otherwise cause transmission line disconnection, allowing the use of lower resistance terminating loads for power efficiency.
Solution Approach 2:
The control circuit monitors the connection status and data signal characteristics, then adjusts the blocking signal accordingly. This feedback mechanism ensures that DC current is blocked while maintaining proper signal transmission, enabling lower power consumption without compromising connection stability.
3Measurement precision
If a high-pass filter is formed with a 0.1-μF capacitor and 50-Ω terminating load, then cutoff frequency is achieved, but device area increases and DC current flows through the transmission line
Solution Approach 1:
The invention extracts the high-pass filtering function from the physical capacitor and implements it through control signal processing. The control circuit generates blocking signals that achieve the same frequency-selective effect without requiring large capacitive components, reducing package substrate area while maintaining cutoff frequency performance.
Data Source
AI summary
An embodiment is a connecting circuit connected to the preceding stage of a transmission circuit and configured to receive a data signal includes an initial voltage value holding circuit, and a terminating load connected in series with the initial voltage value holding circuit. The initial voltage value holding circuit outputs, to the terminating load, an initial voltage value obtained when no data signal is input, and sets both ends of the terminating load at the same potential by a DC component.