Serializer Driver Timing to Reduce Power-Supply Noise
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Solution Overview
Problem
High-speed digital communication systems face errors and reduced speed performance due to power supply fluctuations caused by parasitic resistive, inductive, and capacitive impedances, despite efforts to minimize these fluctuations through improved voltage regulation and balanced symbol patterns.
Innovation Solution
A transmitter merges even and odd data streams to drive a serialized signal, using pre-drivers to synchronize the charge and discharge of parasitic capacitances in drivers, which reduces supply current fluctuations and noise by matching charge and discharge currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If improved voltage regulation and reduced supply impedance are used, then supply voltage stability is improved, but device complexity increases
Solution Approach 1:
The patent employs a replica transmitter that copies the structure and operation of the actual transmitter. The replica includes identical drivers, pre-drivers, and parasitic capacitances, allowing it to generate compensating currents that mirror the actual transmitter's current fluctuations without requiring complex voltage regulation circuitry
Solution Approach 2:
The patent introduces a compensating current mechanism as an intermediary between the power supply and the transmitter. The replica transmitter generates compensating currents that are injected into the supply node, acting as a mediator to counteract current fluctuations without modifying the power supply itself
2Stability of the object's composition
If balanced symbol patterns or compensation currents are used, then supply current fluctuations are reduced, but device complexity increases
Solution Approach 1:
The replica transmitter is an exact copy of the actual transmitter, including matched drivers and pre-drivers. This copying approach enables the replica to generate compensating currents that precisely match the current fluctuations of the actual transmitter, providing effective supply current stabilization
Solution Approach 2:
The system uses the transmitter's own structure and operation to generate its own compensation. The replica transmitter leverages the same parasitic capacitances and driver configurations as the actual transmitter, allowing the system to self-compensate for its own current fluctuations without external intervention
3Object-affected harmful factors
If pre-drivers synchronize charge and discharge timing, then supply noise is reduced, but device complexity increases
Solution Approach 1:
The pre-drivers perform preliminary synchronization of the charge and discharge timing for the parasitic capacitances. By advancing the timing control, the system ensures that charge and discharge currents are properly aligned before they occur, reducing supply noise through proactive timing management
Solution Approach 2:
The system employs periodic clock signals to control the alternating charge and discharge cycles of the parasitic capacitances in the replica and actual transmitters. This periodic action ensures synchronized operation and maintains current balance throughout the transmission cycle
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes supply voltage fluctuations and noise, maintaining a relatively constant supply current during symbol transitions, thereby enhancing the performance and reliability of high-speed digital communication systems.
Implementation Method 1
Each driver includes transistors with parasitic capacitances that are charged when the driver is actively driving a symbol and discharged when the driver is inactivated
Data Source
AI summary
A transmitter merges even and odd data streams to drive a serialized signal. Identical even and odd drivers take turns driving symbols from respective even and odd streams using respective pull-up transistors and pull-down transistors. Each transistor exhibits a significant source-gate capacitance that is charged when the transistor is turned onto drive the serialized signal. Charging one of these capacitances loads the power supply and thus introduces noise. Each even and odd driver includes a pre-driver that times the charging of a source-gate capacitance in the active driver to the discharge of a source-gate capacitance in the inactive driver. The discharge of the source-gate capacitance in the inactive driver counters the effect of charging the active driver, providing much of the power required by the active driver and thus reducing supply noise.