Patent ID: 8866554
Filing Date: 2014-10-21
Classification: H03F

Abstract:
1. An amplifier circuit with improved slew rate comprising: a differential pair of transistors comprising a first transistor and a second transistor, the first transistor having a first control terminal, for receiving a first control signal, a first current handling terminal, and a second current handing terminal, the second transistor having a second control terminal, for receiving a second control signal, a third current handling terminal, and a fourth current handing terminal, the first current handling terminal and the third current handling terminal being coupled to a common tail current source, the tail current source providing a tail current for the differential pair of transistors; a slew boost controller having a first output terminal coupled to the tail current source, the slew boost controller having a fourth control terminal, for receiving the first control signal, and a fifth control terminal, for receiving the second control signal, the slew boost controller generating a slew boost output signal at the first output terminal corresponding to a difference between the first control signal and the second control signal; and a tail current regulator coupled to the first output terminal of the slew boost controller, the tail current regulator generating a bias signal for controlling the tail current source to output a minimum tail current, wherein the tail current regulator controls the tail current to be a minimum tail current until the slew boost output signal exceeds a threshold, whereupon the slew boost output signal increases the tail current in response to an increasing differential between the first control signal and the second control signal for improving the slew rate of the amplifier.