Programmable filters and methods of operation thereof

摘要

Programmable filters are used for the purpose of changing the filter cutoff frequency as may be necessary for the operation of a wireless transmitter or receiver. Frequencies may be changed by selecting a desirable value of a capacitor and/or a resistor. The programmable filter controls the frequency according to the disclosed method. Furthermore, in order to reduce the area consumed by the programmable filter a three-dimensional layout is used. In accordance with the disclosed invention it is possible to program the input of the programmable filter to have a higher or lower input resistance as may be required while maintaining the desired programmed cutoff frequency by switching the respective capacitors in a capacitor bank, thereby combining the elements needed for frequency programmability and input impedance level selection.