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US 4,290,027 AGranted
Fail-safe active bandpass filter using a modified twin-T filter
AssigneeGeneral Signal Corporation
InventorJohn W. Parker
Life of this patent
Estimating the term…
Abstract
A fail-safe active bandpass filter circuit is disclosed; that is, one having voltage gain and which is arranged to be fail-safe in the sense that opens, shorts and component value changes will not cause the circuit to self-oscillate and thereby produce a spurious signal that would cause unsafe effects.
Claims9
A fail-safe active bandpass filter circuit comprising:
- a first section including a twin-T filter network, which has a plurality of resistors and capacitors, connected between a first point and a second point, the voltage gain of said network being greater than one;
- a power source connected to said twin-T network;
- a second section including a first resistor connected between a common or reference point and the input of said twin-T network;
- a second, feedback resistor connected from the output to the input of said twin-T network such that the loop gain is less than one.
1 more element
Dependencies are inferred from the claim text.