Adjustable CML Output Impedance for Multi-Standard Signal Links
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Solution Overview
Problem
Current CMOS logic circuits are limited in their ability to be flexibly applied across various high-speed transmission applications due to fixed parameters, such as common-mode voltage and current consumption, which do not align with the diverse requirements of signals like DP, HDMI, MHL, and USB.
Innovation Solution
A current-mode logic circuit with an adjustable output impedance circuit and switch circuit, incorporating floating resistors and pull-up resistors, allows for adjustable common-mode voltage and current consumption, enabling flexible application across different high-speed signal transmission applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed-parameter CML circuits are used, then circuit structure is simple, but adaptability to different applications is poor
Solution Approach 1:
The patent implements dynamic adjustability by introducing switch circuits that can dynamically change the connection states of resistors, transforming the fixed-parameter circuit into one with adjustable parameters. The switch circuits enable real-time reconfiguration of the common-mode voltage and current consumption based on different application requirements, resolving the contradiction between adaptability and complexity.
Solution Approach 2:
The patent changes the electrical parameters of the circuit by introducing adjustable resistance elements (floating resistors and pull-up resistors) controlled by switch circuits. These parameter changes allow the same circuit structure to adapt to different applications by modifying common-mode voltage and current consumption without requiring complete circuit redesign.
2Adaptability or versatility
If common-mode voltage and current consumption are fixed, then circuit design is simple, but flexibility for various signal standards is limited
Solution Approach 1:
The patent segments the resistance elements into multiple independent components (floating resistors and pull-up resistors) that can be individually controlled by switch circuits. This segmentation allows independent adjustment of different resistance values to achieve desired common-mode voltage and current consumption for various signal standards without affecting other circuit functions.
Solution Approach 2:
The patent creates a universal circuit structure that can support multiple signal standards (DP, HDMI, MHL, USB) through the addition of switch circuits and adjustable resistors. The same basic CML circuit topology serves multiple functions by reconfiguring its parameters, eliminating the need for separate dedicated circuits for each signal standard.
3Productivity
If one CML circuit is designed for a specific application, then optimization for that application is achieved, but reuse in other applications is not possible
Solution Approach 1:
The patent enables the CML circuit to maintain application-specific optimization while achieving reuse across different applications through dynamic parameter adjustment. The switch circuits allow the optimized circuit design to be reconfigured for different signal standards, maintaining performance optimization for each specific application while enabling broad reuse through parameter flexibility.
Data Source
AI summary
A current-mode logic circuit is provided. The current-mode logic circuit includes a transmitter module. The transmitter module includes an output impedance circuit, a switch circuit, and a current source. The output impedance circuit provides an adjustable output resistor. The adjustable output resistor includes floating resistors and/or pull-up resistors. The switch circuit is coupled to the output impedance circuit. The switch circuit receives differential input signals, outputs differential output signals, and controls high-low level switching of the differential input signals and the differential output signals according to the adjustable output resistor. The current source is coupled to the output impedance circuit and the switch circuit. The current source provides currents to the output impedance circuit and the switch circuit. The floating resistors are resistors coupled between the differential output signals, and the pull-up resistors are resistors coupled between the differential output signals and a power source.