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Kevin Weddle

IC's

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Many integrated cirucuits have either no resistors or a few low value ones. So how much do they offer to designs?

And many IC's have a wide range of operation. Would a small IC, like a voltage regulator, use many different types of transisotrs?

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I think a high value resistor uses a lot of space on an IC. A transistor constant-current-source (or sink) and a transistor current mirror work better and use a very small amount of space.

A voltage regulator IC uses about 20 transistors plus some resistors and diodes. The schematic is in its datasheet. It has at least one frequency compensation capacitor for its error amplifier. Most transistors are small except for the series pass power transistor and maybe its driver transistor.

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A transistor constant-current-source (or sink) and a transistor current mirror work better and use a very small amount of space.


Nothing I've read describes the drawbacks of not operating transistors under normal biasing conditions. Such as turning a transistor on and off is not the same as a transistor operated linearly. Using transistors to control gain by creating impedance seems not to be good design, although IC's do it all the time. Maybe better circuits would not use an IC, except for it's advantages due to the manufacturing.

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