Hitachi, Ltd.

Hiroshi Hatashita

Takeshi Saitoh

Toshio Nagashima

Susumu Yamamoto

Shigeo Matsuura

Masaki Noda

Keiro Shinkawa

Mitsuhisa Shinagawa

Minoru Moteki

Tomomi Matsumoto

A receiver apparatus having a mixer circuit, an oscillator circuit and a tuner circuit is provided with a trap circuit, interposed between the tuner circuit and the mixer circuit, for removing disturbing mutual modulation waves generated by receiving two or more RF signals. Further, the mixer circuit employs a double balanced mixer structure to offset two or more disturbing mutual modulation waves.

Receiver apparatus

A receiving circuit for receiving an FM-modulated television signal with an energy dispersal signal superposed thereon is used for a television receiver for receiving the FM-modulated television signal. The receiving circuit is provided with a triangle wave signal generator for generating a triangle wave signal in synchronism with a vertical synchronizing signal. The energy dispersal signal superposed on the FM-modulated television signal is suppressed by frequency modulating an oscillation signal of a local oscillator by the triangle wave signal obtained.

FM television signal receiving circuit

An oscillator circuit suitable for use in a local oscillator of a tuner of a television receiver set. A feedback circuit comprised of a feedback capacitor (17) is connected between a junction of a tuning diode (10) and a correcting capacitor (11) connected in series therewith and the emitter of an oscillation transistor (1). Oscillation voltage developing across the correcting capacitor is fedback to the emitter of the oscillation transistor through the feedback capacitor. When the tuning diode is conditioned to have a large capacitance value, a large oscillation voltage is fedback to the transistor through the feedback capacitor whereas when the tuning diode is conditioned to have a small capacitance value, a small oscillation voltage is fedback to the transistor through the feedback capacitor. The oscillator circuit continues to oscillate stably over a wide frequency range whenever the tuning diode changes from the small capacitance value to the large capacitance value or vice versa.

TV Tuner oscillator with feedback for more low frequency power

A double-superheterodyne tuner for a television receiver comprises a tunable oscillator, a fixed oscillator, two mixer stages and a band-pass filter between the mixer stages, and operates at a GHz intermediate frequency between the mixer stages. The two oscillators and the bandpass filter each includes a microstrip line resonator formed in a dielectric body having substantially the same dielectric constant and dielectric constant temperature coefficient to each other, thereby compensating the variation of the resonant frequency in the resonator due to an ambient temperature variation.

Wide-band tuner having a temperature-compensated microstrip resonator

A double superheterodyne tuner including a first and a second frequency converter and a bandpass filter, constituted of microstrip lines, wherein the substrate in which the bandpass filter is built is disposed back to back with the substrates in which the first and second frequency converters are constructed, with the substrate for the bandpass filter extending over the first and second frequency converters, so that a sufficient high-frequency isolation of circuit elements can be effected by the use of smaller shielding plates, the overall size can be reduced and a uniform grounded condition can be obtained.

Double superheterodyne tuner

In a band pass filter of micro strip line structure, an input conductor, an output conductor, a first open end conductor and a second open end conductor are provided. The first and the second open end conductors are located opposite to the input and the output conductors forming narrow gaps between said open end conductors and said input and output conductors. The mutual inductance between the first and the second open end conductors is adjusted by selecting the width of the gap between the first and the second open end conductors.

Band pass filters

A thick film multilayer substrate using a green ceramic sheet is constructed such that at least three conductor layers and at least two dielectric layers are alternately arranged in turn on the green ceramic sheet substrate, a power supply line being formed in the second conductor layer and thus interposed between the first and third conductor layers in which grounded conductors are formed.

Growing community of inventors

Yokohama, Japan

Hiroshi Hatashita