Second order active filters
First Claim
1. A filter comprising:
- an input terminal, an output terminal, and a common terminal;
a first amplifier having an output coupled to the output terminal;
a second amplifier having an input coupled to the output terminal;
a first resistor coupled between an output of the second amplifier and a first junction point;
a first capacitor coupled between the output of the second amplifier and a second junction point;
a second capacitor coupled between the first junction point and an input of the first amplifier;
a second resistor coupled between the second junction point and the input of the first amplifier;
a third capacitor coupled between the first junction point and one of the input and common terminals; and
a third resistor coupled between the second junction point and one of the input and common terminals;
at least one of the third capacitor and the third resistor being coupled to the input terminal.
3 Assignments
0 Petitions
Accused Products
Abstract
A second order active filter comprises an input terminal, an output terminal, and a common terminal, a capacitive T-network comprising three capacitors and, in parallel therewith, a resistive T-network comprising three resistors, the terminals of the T-networks being connected respectively via a first amplifier to the output terminal, via a buffer to the input terminal, and to the common terminal, a potential divider between the output and common terminals, and a second amplifier having an input coupled to a tapping point of the potential divider and an output coupled via a resistor to the central junction of the capacitive T-network and via a capacitor to the central junction of the resistive T-network. In different configurations of the filter, the component coupled to the common terminal may be omitted from one of the T-networks, or from both of the networks with another potential divider coupled between the input and common terminals and a third amplifier coupling its tapping point to one of the networks.
9 Citations
12 Claims
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1. A filter comprising:
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an input terminal, an output terminal, and a common terminal; a first amplifier having an output coupled to the output terminal; a second amplifier having an input coupled to the output terminal; a first resistor coupled between an output of the second amplifier and a first junction point; a first capacitor coupled between the output of the second amplifier and a second junction point; a second capacitor coupled between the first junction point and an input of the first amplifier; a second resistor coupled between the second junction point and the input of the first amplifier; a third capacitor coupled between the first junction point and one of the input and common terminals; and a third resistor coupled between the second junction point and one of the input and common terminals; at least one of the third capacitor and the third resistor being coupled to the input terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification