Selectable Driver Resistance for Symmetric High-Speed Signaling
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Solution Overview
Problem
Semiconductor devices face challenges in maintaining signal transmission characteristics, particularly with nonlinear I-V characteristics, which lead to unstable eye patterns and reduced window widths due to varying termination resistance values and reference voltages, making it difficult to achieve both low power consumption and high signal speed.
Innovation Solution
A semiconductor device with a driver section that includes transistors and resistance elements with adjustable ON resistance values, allowing for a linear I-V characteristic, enabling adaptation to various conditions and ensuring symmetric eye patterns by selecting appropriate transistors and resistance elements to match target resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If Vtt termination is performed with termination voltage set to 1/2 of power supply voltage to maintain symmetric eye pattern, then signal transmission stability is improved, but reference voltage level cannot be raised above 1/2 VDD which limits operation speed and power consumption optimization
Solution Approach 1:
The patent changes the termination voltage parameter from 1/2 VDD to VDD, and introduces a level shifting mechanism that transforms the received signal levels. This allows the reference voltage to be effectively raised above 1/2 VDD while maintaining proper signal recognition, thereby improving operation speed and power consumption characteristics without sacrificing eye pattern stability
2Speed
If termination voltage Vtt is set to power supply voltage VDD to raise reference voltage level above 1/2 VDD for higher speed operation, then operation speed and power consumption are improved, but eye pattern becomes asymmetric and transmission stability deteriorates
Solution Approach 1:
The patent introduces a level shifting mechanism as an intermediary between the VDD-level termination circuit and the receiver. This level shifter transforms the asymmetric signal levels into a symmetric form suitable for the receiver, allowing the benefits of high termination voltage (improved speed and power efficiency) to be realized while maintaining eye pattern symmetry and transmission stability
3Stability of the object's composition
If transistor ON resistance is adjusted to compensate for varying termination resistance and reference voltage, then signal transmission characteristic stability is improved, but device complexity increases due to multiple transistors and resistance elements
Solution Approach 1:
The patent implements dynamic adjustment of transistor ON resistance through selection circuits that can choose between multiple transistor pairs with different resistance characteristics. This dynamic adaptability allows the driver section to optimize its output resistance to match varying termination conditions and reference voltage levels, maintaining stable signal transmission characteristics without requiring a fixed complex structure
4Adaptability or versatility
If multiple transistor pairs with different ON resistance values are provided to adapt to various termination conditions, then adaptability to different conditions is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent segments the driver section into multiple selectable transistor pairs, each optimized for specific termination conditions. The selection circuit enables choosing the appropriate segment (transistor pair) based on the operating conditions, achieving high adaptability without requiring all transistor pairs to be simultaneously active, thereby managing device complexity through controlled segmentation rather than monolithic complexity
Data Source
AI summary
A semiconductor device of the invention has a plurality of P-channel transistors, to which resistance elements are inserted in series, prepared on a pull-up side of a driver such that an ON resistance value on the P-channel transistor side and a resistance value of the resistance element can be selected. In addition, also on a pull-down side of the driver, a plurality of N-channel transistors to which resistance elements are inserted in series are prepared such that an ON resistance value on the N-channel transistor side and a resistance value of the resistance element can be selected. A driver section having a linear current-voltage characteristic is realized by combination of those described.