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US 6,388,477 B1Granted
Switchable voltage follower and bridge driver using the same
AssigneeSunplus Technology Col, Ltd.
InventorDar-Chang Juang
Life of this patent
Estimating the term…
Abstract
A switchable voltage follower and a bridge driver that utilizes the voltage follower. The voltage follower has an output transistor pair, three switching devices and an operational amplifier. Each of the switching devices is controlled by a polarity terminal for switching the circuit to be a pull-up voltage follower or a pull-down voltage follower. The bridge driver is formed by two switchable voltage followers to provide a bridge push-pull driving capability by driving the two switchable voltage followers alternately.
Claims12
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.
2 more elements
A bridge driver having a first and a second switchable voltage followers, each 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, the first and second input terminals of the first switching device being provided as an input low terminal and an input high terminal, respectively, 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;
- 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, the input low terminals of the first and second switchable voltage followers are connected together for being used as a voltage input low terminal;
- the input high terminals of the first and second switchable voltage followers are connected together for being used as a voltage input high terminal;
- the polarity terminals of the first and second switchable voltage followers are inputted with a polarity switching signal and an inverse polarity switching signal, respectively.
4 more elements
Dependencies are inferred from the claim text.