Practical limits of binary-weighted DACs Binary-weighted resistor DACs face real-world constraints. In practice, they are most often limited to which resolution without heroic component tolerances?

Introduction / Context:
There are two common DAC implementations: binary-weighted resistor networks and R-2R ladders. Understanding the practical resolution limits of each informs architecture choice for precision and manufacturability.

Given Data / Assumptions:

• Binary-weighted DAC requires resistor values in powers of two (R, 2R, 4R, 8R, …).
• Switches and op-amp input errors add to resistor tolerance issues.
• Cost-effective precision for large value ratios is difficult to maintain over temperature and production spread.

Concept / Approach:

As resolution increases, binary-weighted DACs demand resistor ratios over a wide dynamic range, making matching and absolute accuracy increasingly hard. This rapidly becomes impractical beyond a few bits. R-2R ladders solve this by using only two resistor values (R and 2R), enabling higher resolutions with reasonable tolerance and layout.

Step-by-Step Solution:

Verification / Alternative check:

Textbooks and lab practice commonly reserve binary-weighted designs for demonstrations (3–4 bits) and use R-2R ladders for 8–16 bit DACs.

Why Other Options Are Wrong:

• R/2R ladder is a different architecture, not a “limit.”
• 8-bit binary-weighted is theoretically possible, but impractical with standard tolerances and switch errors.
• Op-amp comparator is not a DAC resolution category.

Common Pitfalls:

• Assuming perfect resistor matching is easy; in practice, tolerances and temperature coefficients dominate error budgets.

Final Answer:

4-bit D/A converters