Power amplifier stage of the voltage follower type
AssigneeU.S. Philips Corporation
InventorGilbert Gloaguen
Life of this patent
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Abstract
The amplifier stage comprises at the output two MOS power transistors in series between a positive supply line and earth, the gate of each of these being controlled by a respective amplifier. An input signal is applied to the input of these amplifiers so as to be compared with an output signal of the amplifier stage. The amplifiers are each provided with an inhibiting input with which it is possible to connect to earth the gate of the corresponding power transistor, and the amplifier stage comprises two transistors which act as switches achieving that either the one or the other of the inhibiting inputs is connected to earth, so that a simultaneous conduction of the power transistors is excluded.
Claims7
A power amplifier stage of the voltage follower type which receives an input voltage signal (Vi) and supplies an output signal (Vo), said stage comprising at the output a first MOS power transistor having a source coupled to a common mode line in series with a second MOS power transistor having a drain coupled to a positive supply line, said first and second power transistors being of the same conductivity type and having a common junction point supplying said output signal of the stage;
- a first amplifier supplying a first control signal to the gate of the first MOS power transistor, a second amplifier supplying a second control signal to the gate of the second MOS power transistor, said first and second amplifier each receiving the input signal at a respective first input and the output signal at a respective second input, wherein to exclude a simultaneous conduction of the two MOS power transistors each of the amplifiers is provided with an inhibiting input and arranged so as to supply a gate control signal equal to the common mode voltage when said inhibiting input is brought to the same common mode voltage, and a first switching transistor of the MOS field effect type having its gate coupled to the gate of the first MOS power transistor, its drain connected to the inhibiting input of the second amplifier and its source coupled to a common mode line, and a second switching transistor of the MOS field effect type having its source coupled to a common mode line, its drain connected to the inhibiting input of the first amplifier and a gate that receives a signal derived from the gate voltage of the second MOS power transistor.
A power amplifier stage of the voltage follower type which receives an input voltage signal and supplies an output signal, said stage comprising at the output a first MOS power transistor having a source coupled to a common mode line in series with a second MOS power transistor having a drain coupled to a positive supply line, said first and second power transistors being of the same conductivity type and having a common junction point supplying said output signal of the stage;
- a first amplifier supplying a first control signal to the gate of the first MOS power transistor, a second amplifier supplying a second control signal to the gate of the second MOS power transistor, said first and second amplifier each receiving the input signal at a respective first input and the output signal at a respective second input, wherein to exclude a simultaneous conduction of the two MOS power transistors, each of the amplifiers is provided with an inhibiting input and arranged so as to supply a gate control signal equal to the common mode voltage when said inhibiting input is brought to the same common mode voltage, and a first switching transistor of the MOS field effect type having its gate coupled to the gate of the first MOS power transistor, its drain connected to the inhibiting input of the second amplifier and its source coupled to a common mode line, and a second switching transistor of the MOS field effect type having its source coupled to a common mode line, its drain connected to the inhibiting input of the first amplifier and a gate that receives a signal derived from the gate voltage of the second MOS power transistor;
- and including a generator of the voltage-doubling type for providing an additional positive supply voltage higher than the first mentioned supply voltage, said additional voltage used for supplying the second amplifier.
Dependencies are inferred from the claim text.