Multistage Compensation Techniques
In many situations the gain of a two-stage amplifier is not sufficient and more stages are necessary. The traditional approach is to add current follower or voltage follower stages to the two-stage circuits of the previous chapter. These followers do not change the high frequency behavior appreciably, but can nevertheless improve the low-frequency gain. A serious drawback, however, is that the cascodes and emitter (source) followers increase the minimum supply voltage. Since low voltage is an essential step towards low power, a higher supply voltage will directly hamper the obtainable bandwidth-to-power ratio.
KeywordsPhase Margin Voltage Gain Compensation Technique Compensation Capacitor Output Transistor
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