Sony Corporation

Satoshi Yokoya

Nobutaka Takao

Hiroshi Yasuda

Kotaro Takagi

Norio Numata

Taiwa Okanobu

Nobuhiko Watanabe

Takayuki Inoue

Yoshio Shimizu

Noboru Someno

Ryuji Oki

Kanji Ohnishi

Ikuo Shimizu

Akira Todo

Yukinobu Kawamura

Jon Strom

A radio communication apparatus capable of varying the level of its transmission output, includes a receiving circuit, a transmitting circuit, an amplifier, an extractor, a detector, a variable voltage converter and a control circuit. The receiving circuit receives a signal from a second station such as a base station, and the transmitting circuit transmits a signal to the second station. The amplifier amplifies the output signal obtained from the transmitter, and the extractor extracts data from the output signal of the receiving circuit so as to control the level of the transmission output. The detector detects the level of the transmission output obtained from the amplifier, and the variable voltage converter converts a source voltage into the operating voltage of the amplifier. The control circuit produces a control signal to control the magnitude of the operating voltage supplied from the variable voltage converter to the amplifier in response to both the detection signal from the detector and the output signal from the extractor, and supplies the produced control signal to the variable voltage converter. The transmission output obtained from the amplifier is varied by changing the operating voltage supplied from the variable voltage converter to the amplifier.

Radio communication apparatus in which output power is controlled by

An active filter circuit used in a receiver circuit of a cellular telephone or the like has a voltage/current conversion circuit, an integrating circuit and a current dividing circuit. The voltage/current conversion circuit converts an input signal voltage to a signal current. The signal current output by the voltage/current conversion circuit is divided between the integrating circuit and ground. The current dividing circuit divides the signal current output by the voltage/current conversion circuit between the integrating circuit and ground. The current dividing circuit extracts low frequency components of the input signal voltage from the integrating circuit, and adjusts the cutoff frequency with respect to the extracted low frequency components to change the dividing ratio of the signal current output from the conversion circuit between the integrating circuit and ground.

Active filter circuit and portable telephone apparatus

A radio communication apparatus comprises a transmitting circuit, a receiving circuit, an amplifier, a control circuit and a detecting circuit. The receiving circuit receives a signal from an opposite station such as a base station. The transmitting circuit transmits a signal to the opposite station. The amplifier amplifies the signal to be transmitted from the transmitting circuit. The control circuit controls the level of the transmission signal outputted from the amplifier. The detecting circuit detects the reception state in response to the reception level or the error rate of the signal transmitted from the opposite station. And the control circuit selectively switches, in response to the detection signal obtained from the detecting circuit, the output level of the transmission signal obtained via the amplifier from a high-level mode to a low-level mode when the reception state of the signal transmitted from the opposite station satisfies a preset value.

Radio communication apparatus

A power control circuit for use in radio transmitters such as portable telephone sets includes a power amplifier for amplifying the power of a transmission signal to obtain an output signal; control circuits for controlling the amplitude of the signal output by the power amplifier; a limiter for partially limiting the amplitude of the signal from the power amplifier in order to obtain a limited signal; a multiplication circuit for multiplying the limited signal from the limiter and part of the signal from the power amplifier in order to acquire a multiplied signal; a low-pass filter for extracting a DC component of the multiplied signal from the multiplication circuit; and a comparison circuit for comparing the DC component from the low-pass filter with a reference voltage in order to obtain a comparison output. The comparison output from the comparison circuit is supplied to the control circuits, and the control circuits control the level of the signal from the power amplifier so that the DC component from the low-pass filter will become equal to the reference voltage regardless of temperature change.

Power control circuit

A radio communication apparatus comprising a modulating portion for modulating a carrier with a signal to transmit so as to produce a transmissible signal; a signal transmitting portion for transmitting the transmissible signal; a level adjusting portion for adjusting a level of the signal to transmit or a level of a control signal used for controlling the transmissible signal in accordance with digital control data supplied to the level adjusting portions; a memory for storing digital adjusting data; and a control unit for reading the digital adjusting data from the memory and supplying the level adjusting portion with the digital adjusting data read from the memory or modified digital adjusting data obtained based on the digital adjusting data read from the memory as the digital control data.

Radio communication apparatus with programmable signal modulation

A charge pump circuit for charging a capacitor in response to a phase difference between first and second input signals comprises a constant current source for providing a first constant current; a constant current sink for absorbing a second constant current; a circuit for substantially equalizing the magnitudes of the first and second constant currents; and a switching circuit for providing the first constant current and the second constant current flowing in opposed directions to the capacitor through an output terminal of the charge pump circuit in response to the phase difference between the first and second input signals to produce a voltage level across the capacitor corresponding to the phase difference. In a phase locked loop system employing such a charge pump circuit, a phase comparator produces a phase difference signal for controlling the provision of the first and second constant currents by the switching circuit to the capacitor. The capacitor acts as a loop filter supplying the voltage thereacross as a control voltage to a voltage controlled oscillator of the phase locked loop system.

Phase locked loop system having an oscillator providing a phase

Charge pump circuit

A filter apparatus comprised of a multi-layer printed circuit board has a shielded filter with input and output terminals protruding from the circuit board, when the filter is mounted on the printed circuit board. Two insulating substrates form the printed circuit board, and a connective conductive pattern is formed on an inner surface of one of the substrates that faces the other substrate. Conductive layers are formed on respective outer surfaces of the substrate opposing the connection conductive pattern, wherein at least one of the input and output terminals of the filter is connected to the connective conductive pattern and the conductive layers are grounded, thereby shielding the connective conductive pattern.

Filter apparatus

A radiotelephone apparatus employed as a so-called portable telephone or a car telephone includes an outer casing, a chassis base plate provided in the outer casing and mounting an electronic circuit section containing above all a heated element or elements, and a fan containing section containing a heat sink and a fan device connected in a heat conductive relation with the chassis base plate. The electronic circuit section and the fan containing section within the outer casing are isolated from each other by an air current interrupting device for air cooling heated electronic components while preventing dust and dirt in the air from flowing into portions in the casing other than the fan containing section. An air intake window is provided in the vicinity of mechanically operating portion of the apparatus for self cleaning dust and dirt sucked by the air flow through the normal telephone operation.

Radiotelephone apparatus

A radio communication apparatus has a modulating portion for modulating a carrier with a signal to be transmitting so as to produce a transmission signal. A signal transmitting portion causes the transmissible signal to be subjected to power amplification. The transmissible signal is transmitted after having been subjected to power amplification. A cooling device is provided for cooling by force a heat source contained in the signal transmitting portion in response to a condition detector for detecting a temperature condition or an operating condition of the signal transmitting portion. An operation control unit is operative to cause the cooling device to be in operation when a particular temperature condition in which temperature of the signal transmitting portion has exceeded a predetermined value or a particular operating condition in which the signal transmitting portion has been in a predetermined state is detected by the condition dectector.

Radio communication apparatus having cooling means

An electronic apparatus includes a plurality of selectively actuable selection devices for causing the apparatus to perform a plurality of distinct operations. A first actuation of a selection device establishes a first condition to cause the apparatus to generate an externally detectable identification such as by voice synthesis of the selected operation, and a second actuation of the selection device establishes a second condition to cause the apparatus to perform the selected operation and identify the operation on a display. In a preferred embodiment, the selection devices are each a push button actuable from a rest position to a first depressed position to establish the first condition by actuating a first switch, and thereafter actuable from the first depressed position to a second depressed position to establish the second condition by actuating a second switch.

Selectively actuable electronic apparatus

A pilot signal detecting circuit for use in an AM stereo receiver capable of receiving and demodulating AM stereo signals broadcast according to any of several different AM stereo modulation methods, in which the particular method employed in broadcasting the AM stereo signals is determined by detecting the individual pilot signal and providing an indication of the particular method employed in modulating the broadcast AM stereo signal. Replicas of each of the different pilot signal frequencies in each of the different AM stereo modulation systems are generated and a signal containing the pilot signal is extracted from the demodulated received AM stereo signal. The replicas are compared with the extracted pilot signal to determine the identity of the AM stereo modulation system employed in the received AM stereo signal. A phase-locked-loop is employed to extract the pilot signal from the received signal and a synchronous detector and envelope detector are employed to demodulate the left and right channel stereo signals from the received AM stereo signal. Comparison of the replica and the received pilot signal is performed in identical phase detectors which receive a corresponding replica of the pilot signal produced by another phase-locked-loop and a frequency divider.

Pilot signal detecting circuit for AM stereo signals

Decoding or demodulating circuitry can produce stereo right channel and left channel signals from AM stereo signals that have been coded according to any of the well known methods. A stereo sum signal made up of the left and right channel stereo signals added together, and a stereo difference signal made up of the difference between the stereo left and right channel signals are developed and fed to a matrix to interconnect these signals to extract or separate the left and right channel stereo signals. At least one of the known methods of stereo coding requires phase shifting of these two developed signals and suitable phase shift circuitry, along with a switching circuit provides the matrix with the appropriate signals when that method of stereo coding is employed at the broadcast side. The stereo sum signal is developed using envelope detection and the stereo difference signal is developed using synchronous detection, with the synchronous detector employing signals developed in the envelope detection process. When the stereo broadcasting wave belongs to the other coding systems, the stereo sum and difference signals are respectively supplied directly to the matrix circuit through the switches.

AM stereo decoder for multiple coding systems

A phase-locked loop circuit comprises an oscillator, a phase comparator which compares the phase of an input signal with the phase of an oscillator signal, a detector which detects when the phase-locked loop circuit is locked within a predetermined frequency range and produces a corresponding lock detecting signal, and a filter circuit including a variable current source which produces a variable current in response to a change of state of the lock detecting signal to control the bandwidth of the filter circuit, a filter element which receives the variable current, a differential amplifier which receives the phase-compared signal, a current mirror circuit which receives the variable current from the variable current source, and a buffer circuit connected to the filter element which supplies an output signal to the oscillator to lock the frequency of the oscillator signal to the frequency of the input signal.

Phase-locked loop circuit with variable bandwidth filter

An amplitude limiter for an AM broadcast transmitter to minimize energy in the broadcasted signal outside an allocated broadcast bandwidth. The secondary and higher order spectra (i.e. second and higher harmonics) of a broadcasted AM stereophonic signal are minimized by limiting the amplitude of the audio signal, prior to modulation onto the carrier, within a predetermined portion of the audio frequency range. This is achieved by controlling the gain of the audio signals in that predetermined portion as a function of the level of a submodulation component also within that predetermined portion of the audio frequency range.

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Kanagawa, Japan

Satoshi Yokoya