Non-Oscillating High-Gain Differential Amplifier with Few Stages

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01:36:50

This is a very high gain differential amplifier with few stages that does not oscillate with negative feedback. It also has 0V offset voltage assuming it was made perfectly and in a perfect environment.

Edit: Upon further measurements I find that the gain is actually 5.5mA/uV (for every 1uV increase in difference between the two inputs, it outputs an additional 5.5mA) and that the offset voltage between the inputs is 0.1uV (almost exactly).

published 7 years ago

eekee

7 years ago

Seems very good! Limitations discovered: output doesn't go to the rails, limiting its usefulness as a comparator; noise causes a permanent offset, but EC's noise is rather intense.

jason9

7 years ago

The noise causes a permanent offset because of the capacitor connected to ground. If it were removed, it would give “Cannot find solution”. It could be replaced by a relay, but it’s more bulky.

jason9

7 years ago

Comparators usually pull current only, while op-amps push and pull.

jason9

7 years ago

I made a rail to rail version. See “Rail-to-Rail OP-Amp with Few Stages”. It has much less gain, and about a millivolt of offset between the inputs, but it goes rail to rail pretty well.

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