Apparatus for pole frequency tracking in amplifiers and associated methods
AssigneeSilicon Laboratories Inc.
InventorsMehmet Akif Altan, Steffen Skaug
Life of this patent
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Abstract
An apparatus includes an amplifier. The amplifier has two inputs, and an output. The amplifier has a pole in its transfer function. The frequency of the pole depends on the output current of the amplifier. The amplifier further includes a pole frequency tracking (PFT) circuit. The PFT circuit includes a source follower circuit.
Claims20
An apparatus comprising an amplifier having first and second inputs and an output, the amplifier having a pole and a non-dominant pole in a transfer function of the amplifier, wherein a frequency of the pole depends on an output current of the amplifier, the amplifier comprising a pole frequency tracking (PFT) circuit, comprising a source follower circuit, to change a frequency of the non-dominant pole.
An apparatus comprising:
- an operational amplifier having first and second inputs and an output, the operational amplifier having a non-dominant pole, the operational amplifier comprising:
- a first stage to receive first and second input signals;
- a second stage coupled to the first stage, the second stage comprising a pole frequency tracking (PFT) circuit, wherein the PFT circuit comprises a feedback loop to provide a feedback signal as a function of an output current of the operational amplifier to change a frequency of the non-dominant pole;
- and
- a third stage coupled to the second stage, the third stage providing the output current of the operational amplifier at the output.
A method of operating an amplifier, the amplifier having a non-dominant pole and an output to drive a load, wherein a frequency of a pole of the amplifier varies as a function of an output current of the amplifier, the method comprising using a pole frequency tracking (PFT) circuit to provide a feedback signal to preserve stability of the amplifier by changing a frequency of the non-dominant pole.
Dependencies are inferred from the claim text.