Abstract: A tunable filter (66) having a filter characteristic tracking an input signal in accordance with the invention includes a signal source (18) providing a variable frequency signal to be tracked by the filter characteristic; a frequency detector (62) coupled to the signal source for producing a detector output signal which is a function of the frequency of the variable frequency signal; a switching signal generator (64), responsive to the frequency detector output signal, for generating at least one switching signal having a variable frequency proportional to the detector output signal; a first capacitor (112, 126, 150, 152, 156 and 158) having a first terminal coupled to a reference potential and a second terminal; and a first switching circuit (114, 128, 154 and 160) having an input coupled to the variable frequency signal, responsive to the at least one switching signal, and in response to changes in level of the at least one switching signal alternately connecting the input of the first switching circuit to

Abstract: A circuit arrangement for controlling load current of a power MOSFET wherein the load is connected at the source terminal includes a second FET having a defined threshold voltage connected with its drain-source path inserted between the gate and source of the power MOSFET. A third FET connects the gate terminal of the second FET to the drain voltage of the power MOSFET when the power MOSFET is in the conductive condition. When the drain-source voltage of the power MOSFET becomes higher than the threshold voltage of the second FET, the second FET becomes conductive and drives the gate-source voltage of the power MOSFET down.