Abstract: The present invention provides a tuner apparatus operating as a common tuner capable of receiving both satellite digital TV and terrestrial TV broadcasting. A tuner configured, according to the invention operates as follows. As the tuner apparatus receives satellite TV broadcasting, intermediate-frequency signals SIF1 are supplied to its quadrature detector circuit where the SIF1 signals are demodulated into baseband signals SI and SQ by using oscillation signals supplied thereto from its oscillator. As the tuner apparatus receives terrestrial TV or CATV broadcasting, terrestrial TV or CATV broadcast wave signals are supplied to its mixer circuit where these signals are frequency-converted into intermediate-frequency signals SIF1 that fall within the bandwidth of the satellite TV broadcasting SIF1 signals.

Abstract: The invention provides a television reception circuit wherein a front end circuit of a television receiver is integrated and outputting of an image frequency is suppressed. The television signal reception circuit comprises an integrated circuit which in turn includes an automatic gain circuit for controlling a level of an input signal, first and second frequency mixture circuits to which an output of the automatic gain circuit is inputted, a &pgr;/2 phase shifting circuit for supplying local oscillation frequencies having a phase difference of &pgr;/2 from each other to the first and second frequency mixture circuits, first and second &pgr;/4 phase shifting circuits for shifting phases of outputs of the first and second frequency mixture circuits by +&pgr;/4 and −&pgr;/4, respectively, and an addition circuit for adding outputs of the first and second &pgr;/4 phase shifting circuits.

Abstract: The present invention provides a tuner apparatus operating as a common tuner capable of receiving both satellite digital TV and terrestrial TV broadcasting. A tuner configured, according to the invention operates as follows. As it receives satellite TV broadcasting, intermediate-frequency signals SIF1 are supplied to its quadrature detector circuit where the SIF1 signals are demodulated into baseband signals SI and SQ by using oscillation signals supplied thereto from its oscillator. As it receives terrestrial TV or CATV broadcasting, terrestrial TV or CATV broadcast wave signals are supplied to its mixer circuit where these signals are frequency-converted into intermediate-frequency signals SIF1 that fall within the bandwidth of the satellite TV broadcasting SIF1 signals. The first intermediate-frequency signals SIF1 are supplied to the quadrature detector circuit where the SIF1 signals are frequency-converted into second SIF2 signals by using oscillation signals supplied thereto from the oscillator.

Abstract: A double integration type filter circuit, consisting of a pair of integrators connected in series with each other, has a changeover switch for commutating the filter characteristics to a filter configuration which emphasizes portions proper to the characteristics of the filter circuit to facilitate filter adjustment to reduce filter adjustment time and to realize improved accuracy while providing for automatic adjustment of the filter characteristics.

Abstract: A filter adjustment apparatus adjusts the properties of a filter by changing, for example, the circuit constants of a filter connected in series with a signal processing circuit to correspond with desired optimum properties of the filter. The state of the signal processing circuit is changed to a state not affecting the filter adjustment, to thereby eliminate the influence of the signal processing circuit on the filter characteristics, to facilitate and increase precision of the filter adjustment.

Abstract: Filter adjustment apparatus for adjusting cut-off frequencies or dip frequencies, for example, may be adjusted to desired optimum properties, during application of an input signal of a constant frequency. The optimum filter adjustment data are found, based on data manifested when the level detected output of the filter output crosses a prescribed reference level whereby the filter adjustment operation is simplified and accuracy is improved with a simplified structure, and it is possible to achieve automatic adjustment of the filter characteristics.

Abstract: An integrated voltage controllable oscillator having a transistor for oscillation is further provided with a resonance circuit externally connected to two electrodes of the transistor for oscillation and including a variable capacitance element adapted to vary a resonance frequency of the resonance circuit, and a high impedance element connected between the variable capacitance element and the ground in a circuit adapted to supply a control voltage to the variable capacitance element.

Abstract: A tuner for a television receiver is designed for minimal size and to have a series of external terminals placed along one side thereof. An electronic tuning section including several local oscillator circuits is located within a common shielding case and a phase locked loop channel selection circuit is also located within the case in an isolated compartment thereof. The channel selection circuit and the local oscillator circuits all lie along a straight line parallel to and adjacent one end of the case.