Variable-Impedance Series Termination for Mixed P-P and P-MP Links
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Solution Overview
Problem
Existing semiconductor integrated circuit devices face challenges in efficiently managing impedance matching for both Point-to-Point (P-P) and Point-to-Multipoint (P-MP) data transmission types, leading to signal reflection and potential image quality deterioration in radio communication devices.
Innovation Solution
Incorporating variable-impedance series termination circuits in the host IC, which can adjust impedance values based on the number of peripheral devices connected, allowing for seamless operation in both P-P and P-MP data transmission configurations without the need for bridge chips, thereby reducing chip size and circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed-impedance termination circuits are used in the host IC, then the circuit design is simple, but signal reflection occurs when peripheral devices are connected in P-MP configuration
Solution Approach 1:
The termination circuit incorporates switching elements (transistors) that dynamically change the impedance value based on the connection configuration. When a peripheral device is connected in P-MP configuration, the switching elements activate to change the termination impedance from the P-P value to the P-MP value, thereby adapting to different connection scenarios and preventing signal reflection.
Solution Approach 2:
The invention changes the impedance parameter of the termination circuit based on the detection of peripheral device connections. The circuit transitions between different impedance states (P-P impedance and P-MP impedance) by controlling the switching elements, ensuring optimal signal matching for each configuration type.
2Adaptability or versatility
If bridge chips are added to support both P-P and P-MP configurations, then adaptability improves, but chip size and circuit complexity increase
Solution Approach 1:
The termination circuit is designed to perform multiple functions by integrating switching elements that can configure the impedance for both P-P and P-MP modes within a single circuit block. This eliminates the need for separate bridge chips or dedicated termination circuits for each configuration type.
Solution Approach 2:
The invention merges the termination circuit functionality with the host IC by integrating switching elements directly into the host IC's output stage. This consolidation eliminates the need for external bridge chips and reduces overall system complexity while maintaining support for both P-P and P-MP configurations.
3Reliability
If switching elements are added to enable impedance change, then signal reflection is suppressed in P-MP configuration, but circuit complexity increases
Solution Approach 1:
The switching elements are strategically placed only at the output terminals of the host IC where impedance matching is critical. This localized approach allows impedance adjustment only where needed for P-MP configuration, rather than redesigning the entire termination circuit, thereby minimizing the increase in overall circuit complexity.
Data Source
AI summary
In an embodiment, a semiconductor integrated circuit device includes a driver circuit that drives a transmission line, an output terminal coupled to the output of the driver circuit, and a variable-impedance circuit. The variable-impedance circuit is coupled, for example, between the driver circuit and the output terminals for series-termination of the transmission line.