Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression
Reexamination Certificate
2007-07-17
2007-07-17
Le, Dinh T. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Unwanted signal suppression
C327S557000, C327S077000
Reexamination Certificate
active
11600847
ABSTRACT:
An analog filter circuit in which filter characteristic deviation can be adjusted with simple circuitry and its adjustment method can be provided. The analog filter circuit includes a low pass filter and a high pass filter and output signals of both filters are input to a comparison and adjustment section from which an adjustment signal is fed back to the low pass and high pass filters and also input to a predetermined-band pass filter having predetermined correlation to the low pass and high pass filters. The low pass and high pass filters are tuned so that the frequency-gain characteristic line in an attenuation band of the low pass filter linearly falls, while that line of the high pass filter linearly rises, both the lines crossing at a reference frequency. When filter characteristic deviation occurs, it is adjusted to compensate gain difference between the output signals produced by filtering the reference signal with a reference frequency and, accordingly, the predetermined-band pass filter is adjusted to its desired filter characteristic.
REFERENCES:
patent: 5371803 (1994-12-01), Williamson, III
patent: 6538498 (2003-03-01), Lee et al.
patent: 6791401 (2004-09-01), Miwa
patent: 03121610 (1991-05-01), None
patent: 09-083294 (1997-03-01), None
patent: 10-013188 (1998-01-01), None
patent: 2003078392 (2003-03-01), None
Arent Fox LLP.
Fujitsu Limited
Le Dinh T.
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