Low-Swing SERDES Driver for EMIR-Limited On-Chip Links
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Solution Overview
Problem
The increasing demand for metal resources for signal routing and Electro-Migration (EM) and IR drop (IR) requirements poses challenges in designing On-Chip drivers due to competing needs for power integrity and signal routing, especially in high-speed serializer-deserializer (SERDES) schemes, leading to resource bottlenecks and reliability concerns.
Innovation Solution
A low power driver scheme using a voltage-controlled transmitter that converts standard voltage threshold data to non-return-to-zero (NRZ) data for transmission, which is then converted back to standard voltage threshold data at the receiver, employing a process and temperature-compensated biasing scheme to manage threshold switching voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard voltage threshold data transmission is used, then signal integrity is maintained, but power consumption and metal resource demands increase significantly
Solution Approach 1:
The patent changes the voltage parameter from standard voltage threshold levels to low-swing voltage levels. The driver circuit transitions data signals between two voltage levels that are both below the threshold voltage of receiving logic, enabling detection through voltage differential rather than absolute threshold crossing. This parameter change reduces power consumption while maintaining signal integrity through the use of complementary push-pull driving that ensures clean transitions between logic states.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of a voltage-controlled driver with complementary push-pull output stages. This intermediary circuitry converts standard voltage threshold data into low-swing NRZ signals suitable for low-power transmission. The driver acts as a mediator between the data source and transmission medium, transforming the signal format to achieve low power consumption while preserving signal integrity through controlled voltage transitions.
2Reliability
If standard voltage threshold data transmission is used, then reliable data transmission is achieved, but metal resource consumption and EMIR issues worsen
Solution Approach 1:
The patent changes the voltage swing parameter to be substantially less than the threshold voltage of receiving logic, reducing the current required for signal transmission. This parameter change directly reduces metal resource consumption by lowering the magnitude of current flowing through metal interconnects, thereby reducing EMIR (Electro-Migration and IR drop) effects and allowing for more efficient use of available metal routing resources on the chip.
Solution Approach 2:
The voltage-controlled driver serves as an intermediary that transforms standard voltage threshold data into low-swing signals. This intermediary circuit enables reliable data transmission through carefully controlled voltage transitions that minimize current flow through metal interconnects, reducing the quantity of metal resources required and mitigating EMIR issues while maintaining transmission reliability.
3Use of energy by moving object
If low swing voltage level transmission is used, then power consumption is reduced, but voltage threshold switching requirements become more challenging
Solution Approach 1:
The patent employs an voltage-controlled driver as an intermediary device that manages the complexity of voltage threshold control. This driver circuit receives standard voltage threshold data and internally handles the complex task of converting it to low-swing voltage levels suitable for low-power transmission. The intermediary driver absorbs the complexity of voltage threshold management, presenting a simple low-swing signal interface to the transmission medium while maintaining compatibility with standard logic levels at the input and output interfaces.
Data Source
AI summary
Signal routing and EMIR requirements are causing increased demand for metal resources. The cost of metal resources is also an issue. The design and sign-off of on-chip drivers for driving signals from one chip location to another is complicated by requirements for power integrity and signal routing. This disclosure addresses routing resource bottlenecks and power requirements by introducing a low power driver useable in a high speed SERDES scheme. A voltage clipping high speed and low swing driver is disclosed. Threshold switching voltage of the transmitted signal is controlled by a process and temperature compensated biasing scheme. A reference voltage generation circuitry along with a simple receiver demonstrates the capability of this receiver. This transceiver scheme can be used on an on-chip or off-chip SERDES application to send/receive low speed signals serially. Use of this novel technique addresses the metal resource issue along with EMIR and SIPI requirements.