High frequency tunable filter

An integrated circuit comprising a filter, the filter comprising:

• a first resistor network having a first lead coupled to receive an input signal and a second lead coupled to a first lead of a second resistor network;
• a first capacitor having a first lead coupled to said first lead of said second resistor network and a second lead coupled to a first lead of a transistor;
• a first capacitor network having a first lead coupled to a second lead of said second resistor network and to a control lead of said transistor, a second lead of said first capacitor network coupled to a second lead of said transistor;
• wherein said first resistor network comprises a non-switched resistor and a switched resistor connected in parallel with said non-switched resistor, said non-switched resistor and said switched resistor coupling said first lead of said first resistor network to said second lead of said first resistor network;
• wherein said switched resistor comprises a switching transistor coupled in series with a resistor between said first lead of said first resistor network and said second lead of said first resistor network;
• wherein said switching transistor, when enabled or switched on, electrically connects said resistor between said first lead of said first resistor network and said second lead of said first resistor network;
• wherein said switching transistor, when enabled or switched on, adds resistance in series to the resistance provided by said resistor;
• wherein the overall resistance of said switched resistor is calculated to include the resistance of said resistor and the resistance of said switching transistor, when enabled or switched on;
• and
• wherein the resistance of said switching transistor, when enabled or switched on, is at least 20 percent of the overall resistance of said switched resistor.