Settling time comparison: In general, do current-output DACs settle faster than voltage-output DACs of similar resolution and technology?

Introduction / Context:Settling time is the interval a DAC output needs to reach and remain within a specified error band after a code transition. Architecture significantly affects it. Current-steering DACs (current-output) often switch matched current sources directly and hand the summing to a transimpedance node, while voltage-output DACs integrate an internal amplifier that must slew and settle, adding dynamics that can slow the response.

Given Data / Assumptions:

• Comparable process and resolution (e.g., 8–16 bits).
• Proper output compliance for current DACs; suitable I/V op-amp bandwidth.
• No excessive output loading or layout parasitics skewing results.

Concept / Approach:Current-output (current-steering) DACs use fast switching of current cells; the external I/V converter can be optimized for bandwidth. Voltage-output DACs include an internal amplifier that must slew across step changes and recover from glitches, typically producing longer worst-case settling times. Consequently, for high-speed applications (communications, waveform synthesis), current-output DACs are preferred when fast settling and wide bandwidth are priorities.

Step-by-Step Solution:

Verification / Alternative check:Datasheets commonly show sub-100 ns settling for current-output devices of a given resolution, whereas comparable voltage-output devices list longer settling times due to amplifier dynamics and output buffer stabilization.

Why Other Options Are Wrong:

Common Pitfalls:Ignoring the external I/V op-amp requirements for current-output DACs; a poor I/V stage can negate the advantage.

Final Answer:Correct