Patent ID: 6985707

Claim:
Receiver comprising a resonance amplifier for selectively amplifying a modulated carrier signal, a signal demodulator, operably coupled to the resonance amplifier, for narrow band demodulation of the carrier signal to provide an RF carrier level indicator, an AFC signal generator, a first DC signal (A) being supplied to a first input of the AGC signal generator, the resonance amplifier having a cascade of first and second transconductance amplifiers (TC 1 , TC 2 ) being included in a loop, outputs thereof being coupled via first and second parallel RC filters (R 1 C 1 ; R 2 C 2 ) to inputs of the second and first transconductance amplifiers TC 1 , TC 2 ), respectively, the loop also including a signal inverter (INV), third and fourth transconductance amplifiers (TC 3 , TC 4 ) having inputs and outputs coupled to outputs of the first and second transconductance amplifiers (TC 1 , TC 2 ), respectively, to effectuate a negative resistance value across the first and second parallel RC filters (R 1 C 1 , R 2 C 2 ), respectively, that varies with the gain of the third and fourth transconductance amplifiers (TC 3 , TC 4 ), fifth and sixth transconductance amplifiers (TC 5 , TC 6 ) being coupled between inputs and outputs of the resonance amplifier, wherein the AGC signal generator derives first and second control signals (Iq, Id) from the first DC signal (A), the first control signal (Iq) is supplied to gain control inputs of the third and fourth transconductance amplifiers (TC 3 , TC 4 ) and the second control signal (Id) is supplied to gain control inputs of the fifth and sixth transconductance amplifiers (TC 5 , TC 6 ), the first and second control signals (Iq, Id) increases at an increase of the first DC signal (A) and vice versa, and the first control signal (Iq) is stronger than the second control signal (Id).