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What is comparator offset voltage?
The input offset voltage of a comparator is the input voltage at which its output changes from one logic level to the other. Random circuit noise can cause the output to change from one logic level to the other, even when the comparator input is held constant.
How do I choose a comparator?
An op amp running without negative feedback can serve as a comparator, because its high voltage gain enables it to resolve very small differences in input voltage. Op amps used this way are generally slower than comparators and lack other special features, such as hysteresis and internal references.
How do you calculate the output voltage of a comparator?
Remember the equation Av = -Rf/R1. The equation for voltage gain in the inverting mode is Av = -Rf/R1. Since there is no feedback resistor, the gain will be close to infinity and the output voltage will be as negative as possible ie; V-.
What kind of supply voltage does a comparator use?
Comparators operate with the same supply voltages used by op amps. Many older comparators require bipolar (e.g., ±15V) or unipolar supply voltages as high as 36V. These supply voltages are still used in industrial applications.
When does a comparator change its output state?
A comparator normally changes its output state when the voltage between its inputs crosses through approximately zero volts. Small voltage fluctuations, always present on the inputs, produce very small voltage differences. When the voltage difference is near zero volts, it can cause undesirable changes in the comparator’s output state .
What is the output of a bipolar comparator?
Because comparators have only two output states, their outputs are near zero or near the supply voltage. Bipolar rail-to-rail comparators have a common-emitter output that produces a small voltage drop between the output and each rail. That drop is equal to the collector-to-emitter voltage of a saturated transistor.
What is the voltage range of a unipolar DAC?
For example, Digital to Analog Converters (DACs) may have the output voltage range 0 to 2.5 V, or 0 to 5 V, while the design asks for a range of –5 V to +5 V. To comply with this requirement, we have to design a unipolar to bipolar converter which will be inserted between the DAC output and the following bipolar stage.