| 主权项 |
1. A differential amplifier comprising:
a differential pair stage to receive a pair of input differential signals, and amplify the pair of input differential signals to form a pair of amplified differential signals at a pair of amplifier stage outputs; a driver stage connected to the differential pair stage, the driver stage to drive a pair of output differential signals in response to the pair of amplified differential signals; and a common mode feedback stage connected to the differential pair stage and the driver stage, the common mode feedback stage including:
a RC sensing circuit to generate a measured common mode voltage in response to the pair of output differential signals;a diff-pair circuit connected to the RC sensing circuit, the diff-pair circuit to vary a first diff-pair current and a second diff-pair current in response to a difference between a magnitude of the measured common mode voltage and a magnitude of a reference common mode voltage;a control circuit connected to the driver stage and the diff-pair circuit, the control circuit to sink a first portion of the first diff-pair current, and vary the pair of output differential signals in response to a magnitude of the first portion of the first diff-pair current; anda pull down circuit connected to the control circuit, the pull down circuit to sink a second portion of the first diff-pair current when the magnitudes of the measured common mode and reference common mode voltages are equal, the pull down circuit to reduce the first portion of the first diff-pair current that is sunk by the control circuit and increase the second portion of the first diff-pair current that is sunk by the pull down circuit when the magnitude of the measured common mode voltage is greater than the magnitude of the reference common mode voltage. |
