Analog Delay Feed-Forward Equalizer Without High-Speed Clock Routing
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Solution Overview
Problem
High-speed data transmission in chip-to-chip communication channels is hindered by channel loss and intersymbol interference, leading to inefficiencies in power consumption and system performance due to the use of digital delay elements in n-tap finite impulse response (FIR) transmit equalizers.
Innovation Solution
The implementation of analog delay cells controlled by an analog control voltage, which sets the delay based on phase differences between clock signals, eliminating the need for high-speed clock signals and allowing for programmable tap spacings without complex digital designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital delay elements are used in n-tap FIR transmit equalizers, then timing precision can be achieved, but power consumption increases and area requirements expand
Solution Approach 1:
The patent replaces digital delay elements with analog delay cells that use continuous voltage-controlled delay mechanisms. This substitution eliminates the need for high-speed digital clock signaling while maintaining precise timing control through analog voltage adjustment, thereby reducing power consumption and area requirements.
Solution Approach 2:
The patent changes the control parameter from digital clock cycles to analog control voltages. By using voltage-controlled delay cells where the delay amount is continuously adjustable via analog voltage, the system achieves precise timing control without the power overhead of digital delay elements and high-speed clock distribution networks.
2Measurement precision
If digital delay elements are used in n-tap FIR transmit equalizers, then timing precision can be achieved, but device area increases
Solution Approach 1:
The patent replaces digital delay elements with analog delay cells that use continuous voltage-controlled delay mechanisms. This substitution eliminates the need for high-speed digital clock signaling while maintaining precise timing control through analog voltage adjustment, thereby reducing power consumption and area requirements.
3Measurement precision
If high-speed clock signals are used for digital delay, then timing accuracy is improved, but power consumption and complexity increase
Solution Approach 1:
The patent replaces digital delay elements with analog delay cells that use continuous voltage-controlled delay mechanisms. This substitution eliminates the need for high-speed digital clock signaling while maintaining precise timing control through analog voltage adjustment, thereby reducing power consumption and area requirements.
Solution Approach 2:
The patent introduces an analog control voltage as an intermediary between the clock signal and the delay mechanism. This voltage intermediary allows precise timing control to be achieved without directly using high-speed clock signals, simplifying the overall system architecture by eliminating complex high-speed digital clock distribution networks.
4Use of energy by moving object
If analog delay cells controlled by phase differences are used, then power consumption is reduced, but delay control complexity increases
Solution Approach 1:
The patent employs phase detection circuits that continuously monitor the phase difference between clock signals and automatically adjust the analog control voltage to maintain optimal timing alignment. This feedback mechanism simplifies the control process by eliminating manual calibration requirements while maintaining precise timing control, thereby reducing the perceived complexity despite the analog control architecture.
Data Source
AI summary
An analog-based architecture is used to produce tap spacings in an n-tap UI-spaced equalizer without the need for digital clock-driven elements. The analog voltage-controlled delay cell circuits control the amount of applied delay based on the measured phase difference between quarter-rate clock signals. Because low speed clock signals are sufficient for comparison purposes, the analog delay cells can be placed before the quarter-rate multiplexors in the data path. The use of analog-based delay cells eliminates the need to route high-speed clock signals to multiple digital delay elements that are typically used to achieve UI-spaced data signals in n-tap FIR equalizers. Timing margin issues can also be eliminated since digital clocked elements are not used to produce the UI spaced delays. The analog-based delay approach also consumes less power relative equalizers that use multiple digital delay elements requiring high speed clock signals.