Patent ID: 6388477
Filing Date: 2002-05-14
Classification: H03F

Abstract:
A switchable voltage follower comprising:an output transistor pair having a PMOS transistor and a NMOS transistor, each having a drain connected together for being used as a driving output terminal; a first, a second and a third switching devices, each having a first input terminal, a second input terminal and an output terminal, the first input terminal of the second switching device being connected to a voltage supply, the output terminal of the second switching device being connected to a gate of the PMOS transistor, the second input terminal of the third switching device being connected to a system low voltage, the output terminal of the third switching device being connected to a gate of the NMOS transistor; and an operational amplifier having a positive input connected to the driving output terminal, a negative input connected to the output terminal of the first switching device, and an output connected to the second input terminal of the second switching device and the first input terminal of the third switching device, wherein, each of the switching devices is controlled by a polarity terminal in such a manner that, when the polarity terminal is in a first logic state, the output terminal of each switching device is connected to its first input terminal, and when the polarity terminal is in a second logic state, the output terminal of each switching device is connected to its second input terminal.