Patent ID: 6850747

Claim:
An image trap filter for filtering an image signal from a radio frequency signal, said image trap filter comprising: a first branch having an inductor and a capacitor connected in series, at least one of said inductor and said capacitor being tunable; a second branch connected in parallel with said first branch and having a tunable impedance; and means for tuning; (a) at least one of said inductor and said capacitor in said first branch, and (b) said impedance in said second branch to: (a) resonate said first branch at the frequency of the image signal and present in said first branch at the frequency of the image signal a low impedance, (b) present in said first branch an impedance at the frequency of the radio frequency signal, and (c) resonate said second branch with said first branch to present a high impedance at the radio frequency; wherein (i) said impedance presented in said first branch at the frequency of the radio frequency is inductive, said impedance in said second branch is capacitive, (ii) said capacitor in said first branch is tunable and includes a plurality of capacitors, and (iii) said tuning means includes a plurality of switches individually connected in series with said plurality of capacitors that are selectively closed.