Subscriber Line Interface Circuit With High-Voltage MOS Linefeed
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Solution Overview
Problem
Conventional subscriber line interface circuits are costly and power-intensive due to the need for multiple integrated circuits and direct sensing of tip and ring signals, which makes them susceptible to signal instabilities and requires additional circuitry for calculating common and differential mode signals.
Innovation Solution
A subscriber line interface circuit that includes a linefeed circuit with a signal conversion circuit providing both differential and common mode signals, allowing the subscriber line control circuit to be isolated from the tip and ring signals, reducing the need for signal processing and power consumption, and enabling remote fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional subscriber line interface circuits directly sense tip and ring signals, then signal monitoring is achieved, but the circuit is susceptible to signal instabilities and requires additional circuitry for calculating common and differential mode signals
Solution Approach 1:
The patent introduces an intermediary signal conversion circuit that transforms the directly sensed tip and ring signals into common mode and differential mode signals. This intermediary circuit acts as a buffer between the unstable tip/ring signals and the control logic, providing stable monitoring signals while eliminating the need for complex real-time calculations in the control circuitry.
Solution Approach 2:
The signal conversion circuit performs preliminary transformation of the tip and ring signals into common mode and differential mode signals before they reach the control logic. By pre-calculating and providing these mode signals, the system avoids the need for complex real-time signal processing during operation, thereby reducing circuit complexity and improving reliability.
2Adaptability or versatility
If multiple integrated circuits are used for subscriber line interface functions, then functional requirements are met, but cost and power consumption increase
Solution Approach 1:
The patent merges multiple previously separate integrated circuits into a single unified subscriber line interface circuit. The control logic, signal conversion circuit, and monitoring functions are integrated together, reducing the total number of components, lowering power consumption, and decreasing overall system cost while maintaining all required functional capabilities.
3Adaptability or versatility
If multiple integrated circuits and discrete components are used, then functional requirements are met, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple discrete components and separate integrated circuits into a single integrated subscriber line interface circuit. This consolidation reduces the bill of materials, simplifies assembly processes, and lowers manufacturing costs while preserving all necessary functions including signal conversion, control logic, and fault detection capabilities.
Data Source
AI summary
A subscriber line interface circuit apparatus includes a linefeed circuit and a subscriber line control circuit (SLCC). In an embodiment, the linefeed circuit includes a signal conversion circuit having cross-coupled first and second MOSFETs for providing a differential mode signal and a common mode signal in response to at least a tip signal and a ring signal from the subscriber loop. The linefeed circuit includes a tip control circuit and a ring control circuit, each having two or more MOSFETs. In an embodiment, the SLCC is provided in a single integrated circuit chip and is coupled to the linefeed circuit which isolates the SLCC from the tip or ring signals. The SLCC includes a first and a second differential mode inputs for receiving the differential mode signal, and a common-mode input for receiving the common-mode signal.