Parallel Driver Pre-Emphasis With Constant Output Impedance
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Solution Overview
Problem
Maintaining a constant output impedance in voltage mode drivers while applying pre-emphasis for high bit rate signal transmission is challenging due to impedance mismatches, leading to reduced signal power transfer and distortion.
Innovation Solution
A method involving a bank of parallel, selectively enabled drivers and pre-emphasis path drivers, where the pre-emphasis is updated by adjusting the number of enabled drivers and pre-emphasis path drivers in an inverse relation, maintaining a constant sum to ensure a consistent output impedance, thereby maintaining efficient signal transfer and minimizing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If voltage mode drivers are used for pre-emphasis, then signal power transfer efficiency is improved, but output impedance control becomes difficult
Solution Approach 1:
The patent applies dynamics by making the driver configuration adjustable through selective enabling/disabling of drivers based on operating conditions. The system dynamically reconfigures the number of enabled drivers in the main driver bank and pre-emphasis path driver bank to maintain constant output impedance while varying pre-emphasis levels, resolving the contradiction between voltage mode operation and impedance control.
Solution Approach 2:
The patent changes the parameter of driver population distribution between main drivers and pre-emphasis drivers while keeping the total population constant. By varying the split ratio (n and m where n+m=P) based on operating conditions, the system achieves variable pre-emphasis with constant output impedance, solving the impedance control difficulty in voltage mode drivers.
2Reliability
If pre-emphasis is increased for high bit rate transmission, then signal quality is improved, but impedance mismatch increases
Solution Approach 1:
The patent changes the distribution parameter of driver populations between main drivers and pre-emphasis drivers. By adjusting the split ratio while maintaining constant total population P, the system achieves variable pre-emphasis levels without changing output impedance, thereby improving signal quality for high bit rate transmission while avoiding impedance mismatch.
3Adaptability or versatility
If variable pre-emphasis is applied, then adaptability to different data rates is improved, but output impedance stability deteriorates
Solution Approach 1:
The patent applies dynamics by enabling dynamic reconfiguration of driver populations based on operating conditions such as data rate. The system selectively enables different numbers of main drivers and pre-emphasis drivers according to a predetermined rule, achieving variable pre-emphasis adaptation while maintaining constant output impedance through the constraint that the total number of enabled drivers remains P.
Solution Approach 2:
The patent makes the driver system multi-functional by using the same population of P drivers to serve both main signal transmission and pre-emphasis functions. By selectively enabling drivers in different configurations, the system achieves multiple pre-emphasis levels while maintaining universal output impedance characteristic, resolving the contradiction between adaptability and stability.
Data Source
AI summary
A population of drivers is provided in parallel to a driver output and a population of pre-emphasis path drivers is provided in parallel to the driver output. The population of drivers is updated and the population of pre-emphasis path drivers is updated in an inverse relation to the updating of the population of pre-emphasis path drivers. Optionally, the population of drivers has an initial value of n and the population of pre-emphasis path drivers has an initial value of m, and the sum of n and m is P. Optionally, the updated population of n is n′ and the updated population of m is m′, and n′ is approximately equal to P−m′.