Reference Clock Receiver Termination Switching for LVPECL and HCSL
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Solution Overview
Problem
Designing a reference clock receiver that accommodates different termination schemes with varying common mode and voltage swing level requirements is challenging.
Innovation Solution
The implementation of a reference clock receiver that includes a circuit with multiple transistors configured to allow current flow based on specific control signals, enabling the generation of target resistance and voltage levels. This circuit can be configured for different logic configurations such as LVPECL and HCSL with on-chip termination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a reference clock receiver is designed to accommodate different termination schemes with varying common mode and voltage swing level requirements, then the adaptability and versatility of the receiver is improved, but the device complexity and difficulty of design increase
Solution Approach 1:
The patent implements dynamic termination resistance control by using transistors (first, second, and third transistors) that can be selectively activated or deactivated based on the desired termination scheme. The control signals dynamically switch the termination configuration between different states (e.g., 50 ohm, 100 ohm, or other resistance values) without requiring physical component changes, thereby achieving adaptability while maintaining manageable circuit complexity
Solution Approach 2:
The patent changes the electrical parameters (resistance and voltage) of the termination circuit by controlling transistor switching states. By adjusting which transistors are conductive, the circuit can present different resistance values and voltage levels to match various termination schemes (LVPECL, HCSL, etc.), enabling versatile compatibility through parameter modulation rather than structural redesign
2Adaptability or versatility
If multiple transistors are used to control current flow for different termination configurations, then the flexibility and adaptability of the circuit is improved, but the manufacturing precision requirements and device complexity increase
Solution Approach 1:
The patent employs a set of transistors that serve multiple functions: they can individually control different termination paths, adjust resistance values, and adapt to various logic configurations (LVPECL, HCSL). Each transistor acts as a universal switch that can be programmed through control signals to achieve different termination states, reducing the need for multiple specialized components and simplifying manufacturing tolerances
Solution Approach 2:
The control signals act as intermediaries between the desired termination configuration and the physical transistor states. These control signals translate high-level termination requirements into specific transistor switching patterns, decoupling the complexity of termination scheme selection from the physical component precision requirements, thereby easing manufacturing constraints
3Adaptability or versatility
If the circuit is designed to support multiple logic configurations (LVPECL, HCSL), then the product versatility is improved, but the ease of operation and configuration increases in difficulty
Solution Approach 1:
The termination circuit is designed to automatically configure itself based on control signals that indicate the desired logic configuration (LVPECL, HCSL, etc.). The control logic internally determines the appropriate transistor switching pattern for each configuration type, eliminating the need for manual external configuration and reducing operational complexity while maintaining multi-configuration support
Data Source
AI summary
In an embodiment, a method includes programming a control signal that specifies a target resistance and a target voltage in a circuit. The method further includes sending the control signal to at least one transistor configured to control a current flow in the circuit. The method further includes providing, as an output, a signal with the target voltage and target resistance.