Abstract: A semiconductor device capable of preventing degradation of signal quality due to inclusion of noise and reducing the circuit scale. The constitution of a transmitter/receiver for transmitting/receiving a signal is fabricated on a semiconductor substrate (100). Part of the transmission and reception is performed by analog processing, and the other part is performed by digital processing. The digital processings of the transmission and reception are performed by using a common digital processing unit (20). A reception processing block (10) for analog processing of reception is disposed near a corner of the rectangular semiconductor substrate (100), and digital signal processing unit (20) is disposed near another corner not adjacent to the former corner.

Abstract: The present invention provides a variable gain amplifier including a plurality of initial-stage LNAs 1 to 4 connected parallel to one input terminal IN, a next-stage LNA 5 connected after the initial-stage LNAs 1 to 4 and a variable current source 20 that performs control such that a total value of initial-stage control currents IB1 to IB4 simultaneously flowing through the initial-stage LNAs 1 to 4 is kept constant and such that-next-stage control currents IB13 and IB24 of magnitude proportional to the initial-stage control currents IB1 to IB4 which are let flow through the initial-stage LNAs 1 to 4 are let flow through the next-stage LNA 5, wherein the necessity for causing an excessively large fixed current to flow through the next-stage LNA 5 is eliminated and the next-stage control currents IB13 and IB24 are reduced to a minimum necessary magnitude so that increases of useless current consumption can be suppressed.

Abstract: An FM transmitter which can be easily connected to an existing computer or the like and does not need any troublesome operation is provided. An FM transmitter 100 has an USB device function which can be connected to a PC 400 as an USB host device and comprises a power supply circuit 130 which is connected to the power supply pin of an USB socket 410 to generate a predetermined operating voltage when an USB plug 110 is connected to the USB socket 410 of the PC 400, an USB controller 120 for requesting that its own apparatus being a device audio source inputs/outputs data by isochronous transfer in a configuration performed by the PC 400 and a transmission processing section 140 which is actuated by the operating voltage supplied by the power supply circuit 130 and applies FM-modulation to audio data outputted from the PC 400 via the USB socket 410 for transmission.

Abstract: It is an object of the present invention to provide a variable gain amplifier circuit operable with a low power supply voltage and with less noise generated inside the circuit. In the variable gain amplifier circuit, a third MOS transistor is connected between the respective sources of two MOS transistors constituting a differential amplifier circuit and to the gate of the third MOS transistor, and a DC bias voltage for operating the third MOS transistor in a non-saturated region is supplied. If the output voltage of an AM intermediate frequency variable gain amplifier circuit increases, a control voltage for reducing the resistance between the source and drain of the third MOS transistor is applied to reduce the gain of the AM intermediate frequency variable gain amplifier circuit.

Abstract: The oscillating unit 11 generates a signal having a frequency of n*f, i.e., n times a target frequency f. The control voltage generation circuit 21 compares the phase difference between a divided signal of a signal generated in the oscillating unit 11 and the reference signal, and outputs a DC control voltage according to the phase difference to the oscillating unit 11, thereby controlling an oscillation frequency. The divider circuit 22 converts a signal generated in the oscillating unit 11 to the target frequency f, by dividing the aforementioned signal into n equal units. By setting the oscillation frequency of the oscillating unit at n times the target frequency, the inductance and the capacitors can be formed on a semiconductor integrated circuit board.

Abstract: An object of the present invention is to provide a receiver, a digital-analog converter and a tuning circuit in which temperature compensating components can be formed on a semiconductor substrate while reducing component costs. An FM receiver 100 is constituted by including an antenna 1, a high frequency receiving circuit 2, a local oscillator 3, two digital-analog converters (DACs) 4, 6, a control section 8, a mixing circuit 9, an intermediate frequency amplification circuit 10, a detection circuit 11, a low frequency amplification circuit 12 and the speaker 13. The DACs 4, 6 have a predetermined temperature coefficient, of which output voltage is changed in accordance with ambient temperature. When a characteristic of VCO 31 is changed with variations of ambient temperature so as to cause a control voltage applied to the VCO 31 to be changed, output voltages of the DACs 4, 6 are also changed similarly.

Abstract: An oscillator capable of reducing a noise component when partly formed by using the CMOS process or the MOS process. A high-frequency amplifier circuit, a mixing circuit, a local oscillator 13, intermediate-frequency filters, an intermediate-frequency amplifier circuit, a limit circuit, an FM detection circuit, and a stereo demodulation circuit which constitute an FM receiver are formed as a one-chip component. The local oscillator 13 is formed on a semiconductor substrate by using the CMOS process or the MOS process and the transistors constituting the circuit are p-channel type FETs 21, 22. Moreover, the local oscillator 13 has a resonance circuit whose one end is connected to a DC bias circuit composed of a resistor 27 and the center voltage of the oscillation is set to a value higher than 0 V.

Abstract: The purpose of the present invention is to reduce the noise of an analog circuit of a radio-use semiconductor apparatus. A power supply voltage is supplied to a low-noise amplifier 12 and a partial circuit of a stereo demodulation circuit 16 from an analog-use power supply. A power supply voltage is supplied to a digital circuit 19, an MPXPLL 17, and pilot signal detection circuit 18 of the stereo demodulation circuit 16 from a digital-use power supply that is separate from the analog-use power supply. This configuration prevents noise generated in a digital circuit from propagating to the analog circuit within the stereo demodulation circuit.

Abstract: A limit circuit capable of providing high gain. The limit circuit included in an FM receiver comprises, for example, seven amplifiers (11 to 17), and a BPF (18) inserted substantially in the middle thereof. Each of the amplifiers (11 to 17) operates as a differential amplifier, and has a gain of about 13 dB. The BPF (18) serving as a limit circuit passes components in a bandwidth wider than the bandwidth of the signal to be amplified. The level of 1/f noise and heat noise can be reduced by eliminating low-frequency components and high-frequency components of the Signal amplified by the four amplifiers (11 to 14), respectively. Therefore, each of the amplifiers (15 to 17) connected to the rear end of the BPF (18) is not animated by the noise component.

Abstract: A mobile device equipped with an AM radio, wherein noise to be mixed with AM radio output audio can be reduced. A cellular phone 100 is a mobile device equipped with an AM radio, the mobile device comprising a telephone processing section 10 for performing a predetermined process, while displaying the operational contents on displays 32, 34; and an AM radio tuner section 20, integral to the telephone processing section 10, for receiving an AM radio broadcast and outputting a demodulated audio signal. The mobile device includes an operating section 30 for instructing the AM radio tuner section 20 to commence the reception of the AM radio broadcast: and a control section 40 for changing the display state of the displays 32, 34 when the operating section 30 is used to instruct a reception commencement.

Abstract: An arbitrary threshold value (Ei0) is established which defines a boundary as to activating an RF-AGC circuit (21) if the value of the field intensity (Ei) of a received signal is greater than what value while the value of the field intensity of a signal at a desired frequency being a predetermined value (Ei0) in a weak field area. The established value (Ei0) is used to provide a threshold value establishing/controlling part (22) that controls the ON/OFF of the operation of the RF-AGC circuit (21). In this way, a set maker or the like of an IC including an automatic gain control part (11) can perform a field test or the like such that a preferable value obtained by a result of the field test or the like can be used as an AGC start level (Ei0), whereby an optimum AGC control can be performed based on the preferable AGC start level (Ei0).

Abstract: In order for circuit blocks 1 to 3 composed by the CMOS process, and analog lines 5?1, 5?2, and 5?3 connected thereto not to overlap on the layout, the analog lines 5?1 and 5?2 are wired so that such lines roundabout the layout of the AM/FM common circuit block 3. Through this, the distance of the signal line within the AM/FM common circuit block 3 and the analog lines 5?1 and 5?2 can become as long as possible, the signal line within the AM/FM common circuit block 3 and the analog lines 5?1 and 5?2 would not be coupled via parasitic capacity, and mutual interference occurring between the signal line and the analog lines 5?1 and 5?2 can be suppressed. In another aspect, a semiconductor integrated circuit with a CMOS structure includes an analog circuit and a feedback loop, wherein an analog signal line for the feedback loop is wired outside a layout of the analog circuit.

Abstract: Image processing device and method wherein processing is simplified. The image processing device is provided with line memories 320, 322, 324 for storing image data composed of brightness data of a plurality of pixels constituting an image, a control circuit 334, an address generating circuit 326 and the like for reading out brightness data of 3×3 pixels, which is 9 pixels in total, having a target pixel at the center, among the stored brightness data, and a brightness-data calculating circuit 332 for calculating new brightness data corresponding to the target pixel after image quality adjustment by using the read out brightness data of the 9 pixels.

Abstract: A stereophonic separation can be adjusted without narrowing the dynamic range. Between the sources of a MOS transistor (Q5), to which a composite signal is inputted, and a MOS transistor (Q6), to which a reference voltage is inputted, there are connected in parallel the series connections of resistors and switch elements (R1) and (SW1), (R2) and (SW2), (R3) and (SW3), and so on. The separation level can be so adjusted in DC operations that the resistors (R1 to R5) may exert no influence on the output voltage of the MOS transistor (Q5), and in AC operations that the values of the parallel resistors (R1 to R5) may be varied.

Abstract: A cellular phone with an AM radio, which can reduce noises, as might otherwise be mixed into the output audio of the AM radio. A cellular phone 100 comprises a cellular phone unit 10 for performing a waiting processing, a line connecting processing and a speech processing, which are performed by transmitting/receiving electric waves between itself and a base station, an AM radio tuner section 20 for receiving the AM radio broadcasts and outputting a demodulated audio signal, and a control section 40 acting as telephone function stopping unit for stopping the operations of the cellular phone unit 10 when the AM radio tuner section 20 is operating.

Abstract: A frequency synthesizer includes an AND circuit (17) for detecting whether a frequency synthesizer is in a lock state according to a signal outputted from an Up terminal and a Down terminal of a phase comparator and switching circuits (18, 19) for switching between presence and absence of connections of constant current circuits (14, 15) constituting a charge pump circuit (4) according to the output signal of the AND circuit (17). When the AND circuit (17) has detected a high impedance state of the charge pump circuit (4), the switching circuits (18, 19) disconnects the constant current circuits (14, 15) by the switching circuits (18, 19). Thus, it is possible to eliminate current flowing into the charge pump circuit (4) without using a control signal from outside such as a power cut signal and an intermittent signal.

Abstract: An image processing device wherein processing is simplified. The image processing device 1 performs an image quality adjustment to adjust the quality of an image constituted of pixels arranged along scanning lines. The image processing device 1 comprises three line memories 320 and the like to which brightness data corresponding to the respective pixels is inputted in order of scanning and in which brightness data for adjacent three scanning lines is stored, a control circuit 334 and an address generating circuit 326 for reading out brightness data of 9 pixels in total, i.e. on three pixels continuous in the horizontal positions from each of the three line memories 320 and the like, a brightness data buffer 330 in which the read out nine-pixel brightness data is stored, and a brightness-data calculating circuit 332 for calculating new brightness data which corresponds to the target pixel after image quality adjustment by using the brightness data of the 9 pixels.

Abstract: An object of the present invention is to provide a receiver, a digital-analog converter and a tuning circuit in which temperature compensating components can be formed on a semiconductor substrate while reducing component costs. An FM receiver 100 is constituted by including an antenna 1, a high frequency receiving circuit 2, a local oscillator 3, two digital-analog converters (DACs) 4, 6, a control section 8, a mixing circuit 9, an intermediate frequency amplification circuit 10, a detection circuit 11, a low frequency amplification circuit 12 and the speaker 13. The DACs 4, 6 have a predetermined temperature coefficient, of which output voltage is changed in accordance with ambient temperature. When a characteristic of VCO 31 is changed with variations of ambient temperature so as to cause a control voltage applied to the VCO 31 to be changed, output voltages of the DACs 4, 6 are also changed similarly.

Abstract: A plurality of plane antennas 6-1 and 6-2 are embedded in the equipment body section 1, and every time occurrence of reception failure is detected by the internal electronics circuit, switching between the antennas used is established. Spatial diversity through selectively switching and using the plurality of plane antennas 6-1 and 6-2 is performed. Through this, even when reception sensitivity of one antenna in use deteriorates, good reception sensitivity can be gained through switching to another antenna. Thus, this can avoid inconvenience where calls are cut off.

Abstract: An object of the present invention is to provide a receiver, a digital-analog converter and a tuning circuit in which temperature compensating components can be formed on a semiconductor substrate while reducing component costs. An FM receiver 100 is constituted by including an antenna 1, a high frequency receiving circuit 2, a local oscillator 3, two digital-analog converters (DACs) 4, 6, a control section 8, a mixing circuit 9, an intermediate frequency amplification circuit 10, a detection circuit 11, a low frequency amplification circuit 12 and the speaker 13. The DACs 4, 6 have a predetermined temperature coefficient, of which output voltage is changed in accordance with ambient temperature. When a characteristic of VCO 31 is changed with variations of ambient temperature so as to cause a control voltage applied to the VCO 31 to be changed, output voltages of the DACs 4, 6 are also changed similarly.