Tunable Low Noise Amplifier

摘要

Tunable low noise amplifier using an RF current feed back loop (L) coupled between input (IM) and output (OM) means and including first (CAI) and second (CA 2 ) serially coupled first order lowpass RF current amplifiers as well RF current inverter means (INV). To obtain narrow bandpass selectivity within a relatively wide tuning range e.g. from 40 MHz to 1000 MHz said first RF current amplifier is being provided with a current gain larger than that of the second RF current amplifier, and a 3 dB cut off frequency lower than the 3 dB cut off frequency of said second RF current amplifier, a tuning control signal being supplied to both first and second RF current amplifiers to vary the respective 3 dB cut off frequencies thereof.