Improving serial communication throughput — best practical method Which action most directly increases the bit rate of a synchronous or asynchronous serial link, assuming the medium is unchanged?

Introduction / Context:
Serial communication speed is typically expressed as baud or bits per second. Improving throughput involves increasing symbol rate and/or bits per symbol, within the limits of channel bandwidth, noise, and protocol constraints. This question targets the most direct lever in basic digital links.

Given Data / Assumptions:

• Physical medium unchanged (e.g., existing cable or PCB trace).
• Same modulation scheme and voltage levels.
• Focus on the immediate setting under digital designer control.

Concept / Approach:
For clocked serial links, the symbol rate is set by clock frequency. Raising the clock increases the number of symbols per second, thereby increasing throughput, provided the channel can support the higher bandwidth without excessive intersymbol interference or jitter.

Step-by-Step Solution:
Recognize throughput B ≈ symbols_per_second * bits_per_symbol.With the same coding, bits_per_symbol is constant.Increase symbols_per_second by raising the clock frequency → higher bit rate.

Verification / Alternative check:
Interfaces like SPI/UART clearly specify maximum clock/baud rates; increasing from 1 MHz to 5 MHz SPI, for example, yields a 5× raw throughput increase if timing margins are met.

Why Other Options Are Wrong:

• Using silver/gold instead of copper: negligible speed gain; speed is limited by bandwidth, reflections, and signaling, not conductor material in typical digital runs.
• Adjusting duty cycle: in NRZ signaling, duty cycle follows data; changing it does not raise symbol rate.
• Combining precious metals with faster clocks: metals still do not materially change digital limit; the win comes from the clock increase itself.

Common Pitfalls:

• Ignoring signal integrity; faster clocks require proper termination and layout.
• Confusing throughput with latency; protocol overhead also matters.

Final Answer:
using high-speed clock signals