The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 16, 2008
Filed:
Apr. 25, 2007
Masatoshi Nakabo, Neyagawa, JP;
Mamoru Sekiya, Neyagawa, JP;
Masaaki Inoue, Neyagawa, JP;
Onkyo Corporation, Neyagawa, JP;
Abstract
A low-pass filter with a high signal-to-noise ratio is provided. A low-pass filter includes a first RC filter circuit, a differential operation circuit subtracting an output signal from a low frequency component of an input signal and outputting a differential signal, a second RC filter circuit, a voltage-current conversion circuit, and a capacitor. The voltage-current conversion circuit includes an operational amplifier, a first resistor, and a feedback circuit generating a feedback voltage in accordance with a voltage applied to the first resistor. If resistance values of first to fourth resistors are R, R, R, R, a relational expression of R*R=R*Ris satisfied, and output current i becomes constant regardless of a resistance value of a load resistance. Since only a first resistor is connected between the input and the output of the voltage-current conversion circuit, thermal noise decreases, and a signal-to-noise ratio becomes high.