In a comparator configuration, the threshold voltage is determined by which quantity?

In a comparator configuration, the threshold voltage is determined by which quantity?

• A. Open loop saturation voltage
• B. Vin
• C. Vout
• D. Power supply rails

Answer: (A)

In an open-loop comparator there is no feedback to set a fixed reference. The output will snap to one of the supply rails as soon as the input differential is large enough for the amplifier’s gain to drive the output to its saturation limit. That saturation level—the open-loop saturation voltage—therefore sets the point at which the output switches. In other words, the threshold for switching is governed by how far the output must swing to hit the saturation limit, not by the input signal value itself, the instantaneous output, or the rails alone. Real devices also have small offsets, which can shift this threshold, but the saturating voltage is the quantity that defines the switching threshold in an open-loop configuration.

In an open-loop comparator there is no feedback to set a fixed reference. The output will snap to one of the supply rails as soon as the input differential is large enough for the amplifier’s gain to drive the output to its saturation limit. That saturation level—the open-loop saturation voltage—therefore sets the point at which the output switches. In other words, the threshold for switching is governed by how far the output must swing to hit the saturation limit, not by the input signal value itself, the instantaneous output, or the rails alone. Real devices also have small offsets, which can shift this threshold, but the saturating voltage is the quantity that defines the switching threshold in an open-loop configuration.