Patent ID: 6118332
Filing Date: 2000-09-12
Classification: H03H,H04B

Abstract:
An adjustable high-pass filter comprising:an input for receiving an input signal to be filtered;a main path coupled to said input for conveying a main current, said main path including a first resistor, and an output connected to a sum node, said sum node forming an output of said adjustable high-pass filter;a sub-path also coupled to said input for conveying a sub-current, said sub-path comprising a voltage divider unit having a series arrangement of a plurality of resistors, a first amplifier stage having non-inverting inputs coupled to connections between the resistors of said voltage divider unit, and inverting inputs coupled to an output the first amplifier stage, said first amplifier stage including a selection unit for selecting one of said non-inverting inputs, and a capacitor coupling the output of the first amplifier stage to the sum node;a second resistor connected to the sum node; andmeans for providing a variable, low noise reference potential, said voltage divider unit and said second resistor being coupled to said reference potential providing means, wherein the main current and the sub-current are added at the sum node.