Patent ID: 7855605

Claim:
An amplifier circuit, comprising: a first amplifier unit including an input connector for inputting signals and a first transistor amplifier module connected to the input connector for amplifying the signals; a second amplifier unit including a notch-filter circuit, a main filter circuit and a second transistor amplifier module, the notch-filter circuit and the main filter circuit both connected to the first amplifier unit, the notch-filter circuit connected to the second transistor amplifier module to allow only signals in a predetermined frequency to be transmitted from the first transistor amplifier module to the second transistor amplifier module and amplified, the main filter circuit filtering signals in frequencies different from the predetermined frequency; and a third amplifier unit including a third transistor amplifier module connected to the second transistor amplifier module to amplify the signals transmitted from the second transistor amplifier module and an output connector connected to the third transistor amplifier module for outputting amplified signals.