![]() ![]() Base-emitter junction voltage variation is the major cause of input voltage deviation. Let's see what the causes are and how we can reduce or eliminate their effect.įor bipolar input sections the major cause of input current mismatch is the variation of beta. This will reduce their maximum volume and increase their distortion. Dynamic loudspeakers and headphones are two loads that should not be fed DC signals. ![]() In other applications, offsets can harm following stages or loads. It might also be 101 mV with -1mV offset. For example, if the circuit output measures 100 mV, the signal might be 99 mV with 1 mV of offset. For measurement applications, this offset creates uncertainty in readings. Because all op amps are slightly different, you never know what the exact output offset will be. This difference, or unbalance, is amplified by the remaining stages and will eventually produce a DC voltage at the output. Because of this, their DC bias points are slightly different. One possible example is the fact that the transistors used for the differential amplifier stage will not have identical characteristics. Even though part matching is very close when ICs are made, the parts will not be identical. If op amps were perfect, there would be no such thing as an offset. Offsets are undesirable DC levels appearing at the output of a circuit. ![]()
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