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:
Nov. 25, 1980
Filed:
Feb. 06, 1979
Yasuo Kominami, Kokubunji, JP;
Masanori Ienaka, Kodaira, JP;
Takeshi Wada, Kodaira, JP;
Yukihiko Miyamoto, Tokyo, JP;
Tsuneo Yamada, Tokyo, JP;
Hitachi, Ltd., , JP;
Abstract
A first intermediate frequency amplifier stage which executes the amplitude limiting operation of a double-converting FM tuner employing the integrated circuit technology is constructed in the form of an integrated circuit. An output signal of the first intermediate frequency amplifier stage is put into a square pulse waveform on the basis of the amplitude limiting operation, and therefore has higher harmonic components of high frequencies. When the higher harmonic components are injected into a second mixer circuit in a second frequency converter circuit, various higher harmonic components which have frequencies higher than a second intermediate frequency appear at the output of the second mixer conduit. When the higher harmonic components at the output of the second mixer circuit are injected into an FM demodulator circuit, beat trouble is induced. The second frequency converter circuit is also constructed in the form of an integrated circuit, and filter means to pass the fundamental waves of a first intermediate frequency signal and to reject the higher harmonic frequency components thereof is connected between the output of the first intermediate frequency amlifier stage executing the amplitude limiting operation and the input of the second mixer circuit, whereby the beat trouble can be prevented.