Patent ID: 8803612
Filing Date: 2014-08-12
Classification: H03F

Abstract:
1. A low-noise amplifier with high linearity comprising: a first amplifying stage comprising a first amplifying FET, a signal input connected through a first circuit path to the gate of said first amplifying FET, a first active bias circuit electrically connected to said gate of said first amplifying FET, and a first stage signal output; a second amplifying stage comprising a second amplifying FET, a second stage signal input connected through a second circuit path to the gate of said second amplifying FET, and a signal output connected to said second amplifying FET; an interstage matching network connecting said first stage signal output and said second stage signal input; a second active bias circuit connected to the gate of said second amplifying FET, said second active bias circuit having a feedback network whereby the linearity of said low-noise amplifier is improved by shifting phase and level of signal intermodulation products; said second active bias circuit comprises: a current source; a second stage current mirror FET electrically connected to said current source; and, said feedback path comprising an RC network, wherein said RC network electrically connects the gate of said second stage current mirror FET with the drain of said second stage current mirror FET, and with said gate of said second amplifying FET; said RC network further comprises: a first feedback resistor, a second feedback resistor, and a feedback capacitor; said first feedback resistor having a first terminal electrically connected to said gate of said second stage current mirror FET and to a first terminal of said feedback capacitor, and a second terminal electrically connected to said drain of said second stage current mirror FET and to a first terminal of said second feedback resistor; and said second feedback resistor having a second terminal electrically connected to said gate of said second amplifying FET and to a second terminal of said feedback capacitor.