Amplifiers – With semiconductor amplifying device – Including differential amplifier
Reexamination Certificate
2005-07-19
2005-07-19
Nguyen, Khanh Van (Department: 2817)
Amplifiers
With semiconductor amplifying device
Including differential amplifier
C330S253000, C330S257000, C330S261000
Reexamination Certificate
active
06919766
ABSTRACT:
An operational amplifier circuit includes a first differential pair, which includes first and second transistors, and a second differential pair, which includes third and fourth transistors. A fifth transistor is connected to the first and third transistors. A sixth transistor is connected to the second and fourth transistors. A first current source is connected to the first differential pair to provide a first bias current. A second current source is connected to the second differential pair to provide a second bias current. A third current source is connected to the fifth transistor to provide a third bias current. A fourth current source is connected to the sixth transistor provide a fourth bias current. A control circuit controls the first to fourth current sources such that the sum of the first and second bias currents is constant and the second to fourth bias currents become substantially equal.
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Arent & Fox PLLC
Fujitsu Limited
Nguyen Khanh Van
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