Wide-band linearization technique
AssigneeNortel Networks Limited
InventorWilliam Kung
Life of this patent
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Abstract
A conventional differential transistor pair is provided with a dynamic bias circuit. The input voltage signal for the differential pair is also full-wave rectified and the rectified signal is used to bias dynamically the differential pair while the input voltage signal is being applied. One or more bias transistors having a control electrode fed with the rectified signal is connected in series with the differential pair. The result is that as the input signal magnitude increases the amount of bias increases dynamically and increases linearly for larger signals. Desired responses other than linearity can be achieved by making the signal that is fed to the rectifier vary according to any predetermined function.
Claims9
An amplifier circuit comprising a differential pair of transistors arranged to received an input voltage signal and derive an output current and a dynamic bias circuit for providing bias current to the differential pair, wherein the dynamic bias circuit comprises:
- a bias transistor having a first electrode connected to the differential pair, a second electrode for connection to a bias voltage source and a third electrode;
- means, independent of the output current of the differential pair, for deriving an ac voltage having a predetermined relationship to the input voltage signal;
- and
- a rectifier having an input for receiving the ac voltage and an output connected to the third electrode of the bias transistor, whereby the amount of bias current applied to the differential pair varies dynamically depending upon the ac voltage applied to the input of the rectifier.
Dependencies are inferred from the claim text.