Method of improving linearity of amplifier circuit including magnetically coupled feedback loop and DC bias current adjustment without impacting amplifier gain
AssigneeQuantalRF AG
InventorsAli Fard, Mats Carlsson
Life of this patent
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Abstract
A method of operating an amplifier circuit having a transformer arranged so as to establish a magnetically coupled feedback loop between and output of an amplifier and an input of the amplifier. The method includes providing a DC bias current to the amplifier, and further includes increasing the DC bias current to improve a linearity of the amplifier circuit wherein a transfer gain of the amplifier circuit remains constant when the DC bias current is increased. A loop gain of the magnetically coupled feedback loop is set by selecting a coupling factor and turn-ratio of the transformer.
Claims12
A method of operating an amplifier circuit having a transformer arranged so as to establish a magnetically coupled feedback loop between an output of an amplifier and an input of the amplifier, the method comprising:
- providing a DC bias current to the amplifier wherein a transfer gain of the amplifier circuit depends only on the characteristics of the transformer and is substantially independent of signal level and of inherent gain characteristics of the amplifier when a loop gain of the magnetically coupled feedback loop is at least 10 dB;
- and
- increasing the DC bias current to improve a linearity of the amplifier circuit wherein the transfer gain of the amplifier circuit remains constant when the DC bias current is increased.
A method of configuring an amplifier circuit having a transformer arranged so as to establish a magnetically coupled feedback loop between an output of an amplifier and an input of the amplifier, the method comprising:
- setting a loop gain of the magnetically coupled feedback loop to at least 10 dB by selecting a coupling factor and turn-ratio of the transformer and thereby causing a transfer gain of the amplifier circuit to depend only on the characteristics of the transformer and to be substantially independent of signal level and of inherent gain characteristics of the amplifier.
Dependencies are inferred from the claim text.