A system for implementing a tuner, said system comprising: a Radio Frequency circuit; a filter (110; 510-1) disposed in a signal path in said circuit; a first negative resistance unit (130; 520-1) in communication with said filter (110; 510-1) adapted to cancel one or more resistive elements in said filter (110; 510-1); and a frequency measurement unit (120; 550) in communication with said filter (110; 510-1), wherein said first negative resistance unit (130; 520-1) is adapted to cause said filter (110; 510-1) to act as an oscillator, and wherein said frequency measurement unit (120; 550) is adapted to measure oscillations of said filter (110; 510-1) and to generate a number indicative of a center frequency of said filter (110; 510-1) therefrom; characterised in that said filter (110; 510-1) is a first filter element, said system further comprising a second filter element cascaded downstream from said first filter element (110; 510-1) and in communication with a second negative resistance unit, wherein said second negative resistance unit is adapted to cause said second filter element to act as an oscillator, and wherein said frequency measurement unit (120; 550) is adapted to measure oscillations of said second filter element and to generate a number indicative of a center frequency of said second filter element therefrom, and wherein said frequency measurement unit is configured to measure the oscillations of said first filter element after the oscillations of said first filter element have passed through said second filter element; and a control system in communication with said frequency measurement unit; 550) adapted to adjust a response of said first filter element (110; 510-1) or said second filter element based at least in part upon said respective number indicative of the center frequency. a Radio Frequency circuit; a filter (110; 510-1) disposed in a signal path in said circuit; a first negative resistance unit (130; 520-1) in communication with said filter (110; 510-1) adapted to cancel one or more resistive elements in said filter (110; 510-1); and a frequency measurement unit (120; 550) in communication with said filter (110; 510-1), wherein said first negative resistance unit (130; 520-1) is adapted to cause said filter (110; 510-1) to act as an oscillator, and wherein said frequency measurement unit (120; 550) is adapted to measure oscillations of said filter (110; 510-1) and to generate a number indicative of a center frequency of said filter (110; 510-1) therefrom; characterised in that said filter (110; 510-1) is a first filter element, said system further comprising a second filter element cascaded downstream from said first filter element (110; 510-1) and in communication with a second negative resistance unit, wherein said second negative resistance unit is adapted to cause said second filter element to act as an oscillator, and wherein said frequency measurement unit (120; 550) is adapted to measure oscillations of said second filter element and to generate a number indicative of a center frequency of said second filter element therefrom, and wherein said frequency measurement unit is configured to measure the oscillations of said first filter element after the oscillations of said first filter element have passed through said second filter element; and a control system in communication with said frequency measurement unit; 550) adapted to adjust a response of said first filter element (110; 510-1) or said second filter element based at least in part upon said respective number indicative of the center frequency.