Sony Corporation

Seiichi Nishiyama

Hisao Sakurai

Hiroshi Numata

Ryuichiro Kawai

Kiyoshi Furuya

Yutaka Kamaguchi

Masato Kawata

A frequency divider circuit, and a digital PLL circuit including the same, which can suppress jitter occurring in an output signal, including a first circuit module which drives D-FFs connected in series using an input signal as a reference clock signal and divides the input signal by a frequency division ratio selected by a frequency division ratio determining signal to produce a first divided signal; a second circuit module which drives D-FFs connected in series using the first divided signal as a reference clock signal and divides the first divided signal by a frequency division ratio corresponding to the number of D-FFs connected in series to produce an output signal; and an OR circuit which produces a frequency division ratio determining signal based on the outputs of the D-FFs of the second circuit module and a frequency division ratio selecting signal.

Frequency divider circuit and digital PLL circuit

A clamp pulse generating circuit comprising a synchronizing decision circuit for deciding whether an external synchronizing pulse is being input or not; an exclusive-OR circuit, a change-over switch and a pulse width detecting circuit for deciding whether a video signal containing a synchronizing pulse is being input or not; and a pulse generating circuit for generating a clamp pulse at the front or rear edge of the external synchronizing pulse output from a synchronizing separator circuit, and outputting the clamp pulse at the front edge selected by a selection switch when the external synchronizing pulse is being input and forcing to select and output the clamp pulse at the rear edge of the synchronizing pulse irrespective of the presence of the external synchronizing pulse when the video signal containing the synchronizing pulse is being input.

Clamp pulse circuit

A display unit in which a black level is set to a predetermined level in a first display screen having a first aspect ratio and a black level is set to a predetermined level in a second display screen having a second aspect ratio is provided. A darkest signal of a video signal is detected from an image area corresponding to the second display screen. The darkest signal is lowered to a predetermined level in an image area corresponding to the first display screen. In accordance with the principles of the present invention, the situation where a video signal of the second display screen that is to be lowered will not be lowered can be prevented.

Display unit

There is provided a gain control Gilbert amplifier circuit which can be more easily controlled for variation in the gain characteristics of each predriver integrated circuit for primary color image signals R, G, and B, and the variation caused by light emitting efficiency than the prior art. The gain control Gilbert amplifier circuit also operates in a wider frequency range than the conventional circuits, and has a large S/N ratio. One embodiment of the amplifier circuit comprises a grounded-base transistor amplifier circuit having rectifier elements, reference voltage sources, diodes connected to a differentially paired transistors. The rectifier elements are controlled so that a ratio of currents output from constant-current sources can be selected to enable the frequency characteristic of the amplifier circuit to expand by a frequency range.

Wide frequency range amplifier apparatus

In a wide-band amplifier circuit, a third and a fourth transistors are cascaded externally with a first and a second transistors within an integrated circuit which are connected each to output terminals by collectors through the output terminals, and a collector current flowing in the third transistor is transformed into an output voltage by an external resistance. A load capacity parasitic on the output terminal of the integrated circuit is driven by the collector current, thus a possibility of a frequency characteristic deteriorating due to an influence of the load capacity is avoided, and an operating zone can further be expanded to a high frequency band as compared with a prior art one.

Wide-band amplifier apparatus

In a phase shift circuit apparatus, first and second currents, produced by dividing signal current at a predetermined ratio by a variable bias voltage, are respectively supplied to fifth and eighth transistors which constitute the second differential amplification means, and the first and the second currents are respectively divided at predetermined ratios to supply currents, including square components; third, fourth, fifth and sixth currents which are caused to flow through fifth and sixth transistors of the third differential amplification means and seventh and eighth transistors of the fourth differential amplification means, respectively. Seventh and eighth currents which, produced by dividing signal current at predetermined ratios, are supplied to the ninth and the tenth transistors or the eleventh and the twelfth transistors from the first and the second connection nodes, respectively. In this event, currents which are first and second divided sum currents including square components at predetermined ratio are provided to the first and the second load resistances, and at the fourth connection node there is developed an output voltage by composing the first connection node voltage, which leads the input signal by a phase angle of 45.degree., with the second connection node voltage which lags the input signal by a phase angle of 45.degree., and the gain of the output is substantially constant within a variable range of phase.

Phase shift circuit apparatus

In a control system for peripheral devices, by operating only one device for digital-to-analogue conversion, the specific output switching corresponding to that specific device for digital-to-analogue conversion is closed and the other output switching corresponding to the other device for digital-to-analogue conversion are open so that the only the output signal of that specific device for digital-to-analogue conversion can be output. Thus, the accuracy of operation of each device for digital-to-analogue conversion can be easily evaluated.

Control system for peripheral devices

Disclosed is a wide band amplifier comprising a first differential connection circuit made of a first and a second transistor differentially interconnected, a second differential connection circuit made of a third and a fourth transistor differentially interconnected, and a level shift circuit interposingly provided between a load resistance and a power supply. The load resistance is connected to the collector of the first transistor. The bases of the first and the third transistors are supplied with a voltage for gain determination. Furthermore, the bases of the first and the third transistors are supplied with a predetermined operating voltage. The voltage of the level shift circuit is fed to the collector of the fourth transistor. In this setup, the voltage to the load resistance connected to the collector of the first transistor is varied depending on the magnitude of the current flowing through the fourth transistor.

Wide band amplifier

Disclosed is a a wide band frequency amplifier comprising the following: A first and a second transistor constitute a first push-pull amplifier circuit. A first current source is included, of which one end is connected to the second transistor base, the other end connected to ground. A first bias voltage source is interposed between the bases of the first and the second transistors. A third transistor is coupled with the first transistor in Darlington connection, thereby driving the first and the second transistors using an input signal. A fourth and a fifth transistor constitute a second push-pull amplifier circuit. A second current source is provided, of which one end is connected to the fourth transistor base, the other end connected to ground. A second bias voltage source is interposed between the bases of the fourth and the fifth transistors. A sixth transistor is coupled with the fourth transistor in Darlington connection, thereby driving the fourth and the fifth transistors using the input signal. A phase element is interposed between the second transistor base and the output end of the second push-pull amplifier circuit, thus causing the second and the fifth transistors to operate in Darlington connection at a trailing edge of the input signal.

Wide band frequency amplifiers

A wideband amplifier is provided having a plurality of transistors, the bases of which are commonly grounded, a signal source for generating input signals, an input terminal connected to the signal source, a drive amplifier connected to the input terminal, a plurality of input resistors connected to the drive amplifier and to respective emitters of the transistors, a plurality of load resistors connected to respective collectors of the transistors, and an output terminal connected to a junction where the collector and one of the load resistors are connected with each other.

Growing community of inventors

Kanagawa, Japan

Seiichi Nishiyama