Patent ID: 8909185

Claim:
A method of providing frequency dependent signal attenuation, the method comprising: splitting an RF input signal into a first signal portion and a second signal portion; applying discrete time filtering, a negative group delay and bandstop filtering to the first signal portion to provide a filtered signal portion; applying the second signal portion to a component and receiving a component output signal portion from the component; combining the component output signal portion with the filtered signal portion to provide an RF output signal having frequency dependent attenuation; and applying the negative group delay comprises applying a signal to a negative group delay element, the negative group delay element comprising: a first directional coupler configured to couple the signal onto a first signal path; and a second directional coupler configured to couple a portion of the signal on the first signal path on a second signal path back to the first directional coupler; a time delay element connected between the first directional coupler and the second directional coupler on the first signal path; and a phase shifter and an amplifier connected between the second directional coupler and the first directional coupler on the second signal path.