Rail-to-Rail Amplifier With Integrated Charge Pump Improves Input Offset
by Mike Wong and Tamara Schmitz, Intersil Corporation
In modem electronic systems, the negative power supply is disappearing and the positive power supply voltage is decreasing. This trend is driving the prevalence of rail-to-rail amplifiers. While the supply voltage is changing, the signal level often remains the same. For example, the standard video signal drive level is 2 V and when the power supply comes down to 2 V, the amplifier/buffer must be linear or accurate within the full 2 V supply range. This TechNote focuses on the development of the rail-to-rail amplifier's input stage and discusses in detail the input enhancement circuit that overcomes the deficiencies associated with rail-to-rail amplifiers.
For simplicity, we will limit our discussion to MOSFET amplifiers.
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