Integrated Circuit Selective AC DC Coupling Switching
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Solution Overview
Problem
Existing integrated circuits designed for selective AC or DC coupling require external components to disconnect or short coupling capacitors, leading to increased board space and cost due to the presence of off-chip components.
Innovation Solution
The integration of MOSFET bridges and differential/single-ended drivers within the integrated circuit to selectively short AC coupling capacitors based on coupling mode detection, reducing the need for external components by bringing the switching circuitry inside the IC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If coupling capacitors are used for AC coupling, then AC signal transmission is enabled, but parasitic effects occur when DC coupled and additional components are required to disconnect or short the capacitors
Solution Approach 1:
The patent integrates the switching circuitry directly into the integrated circuit chip, merging the capacitor disconnect/short function with the main IC rather than using separate off-chip components. This reduces the number of discrete components while maintaining the ability to selectively AC or DC couple, thereby reducing device complexity while preserving adaptability.
Solution Approach 2:
The patent extracts the switching function from external components and places it inside the IC, taking out the need for external switches and resistors. This integration eliminates parasitic effects associated with external components and reduces overall circuit complexity while maintaining coupling mode selectivity.
2Adaptability or versatility
If off-chip components are used to disconnect or short coupling capacitors, then coupling mode switching is achieved, but board space and cost increase
Solution Approach 1:
The patent combines the switching circuitry with the main IC, eliminating the need for separate off-chip switches, resistors, and control logic. This integration significantly reduces board space while maintaining the ability to switch between AC and DC coupling modes, as all necessary components are now contained within the single IC package.
Solution Approach 2:
The integrated switching circuitry within the IC serves multiple functions: it controls capacitor disconnect/short operations, detects coupling modes, and manages signal routing. This multi-functionality eliminates the need for multiple dedicated components, thereby reducing board space while maintaining full coupling mode switching capability.
3Adaptability or versatility
If off-chip components are used for coupling capacitor control, then coupling mode detection is achieved, but manufacturing cost increases
Solution Approach 1:
The patent merges the coupling mode detection functionality with the main IC, integrating sensors and control logic within the chip rather than using separate off-chip components. This integration reduces the total component count and assembly steps, thereby lowering manufacturing costs while maintaining the ability to detect and adapt to different coupling modes.
Solution Approach 2:
The IC performs self-detection of coupling modes using integrated sensing circuitry, eliminating the need for external detection components and complex external control logic. This self-service capability simplifies the manufacturing process and reduces costs by reducing component count and assembly complexity while maintaining full coupling mode detection and adaptation capability.
Data Source
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AI summary
An integrated circuit is adapted to be selectively AC or DC coupled to an external device at a coupling point. The integrated circuit includes a first connector connected to the coupling point by way of a coupling capacitor for AC coupling, a second connector connected to the coupling point for DC coupling, and a switch to selectively short the first and second connectors and thereby the coupling capacitor, when the integrated circuit is DC coupled to the device. The switch may be a MOSFET bridge comprising a switch control MOSFET interconnected between the first and second connectors, with the switch control MOSFET receiving at its gate a mode status signal for turning on the switch control MOSFET and thereby shorting the MOSFET bridge when the integrated circuit is DC coupled to the external device. The MOSFET bridge also includes a number of dynamically biased nMOSFETs connected in series with the switch control MOSFET in order to protect switch control MOSFET from high external supply voltages, and a number of dynamically biased pMOSFETs connected in parallel with the switch control MOSFET.