Abstract: The present invention provides a frequency conversion circuit capable of reducing current without impairing high frequency characteristics. A local oscillator amplifier is formed of a first field effect transistor. A source thereof is grounded by a first capacitor in terms of high frequency, and a gate thereof is connected to one end of each of first and second resistors. The other end of the first resistor is grounded, and the other end of the second resistor is connected to a voltage supply terminal. An intermediate frequency amplifier is formed of a second field effect transistor. A source thereof is grounded through a third resistor and a second capacitor that are connected in parallel with each other. A drain thereof is connected to an intermediate frequency signal output terminal through a third capacitor and an intermediate frequency output matching circuit. The source of the first field effect transistor and the drain of the second field effect transistor are connected through an AC blocking circuit.

Abstract: A frequency converter includes: a first terminal through which a local oscillator signal is input; a second terminal through which an input signal with a frequency to be converted is input; a third terminal through which an output signal with a different frequency resulting from the conversion is output; and a field effect transistor with gate, source and drain terminals for converting the frequency of the input signal and outputting the signal with the different frequency as the output signal. The gate terminal is connected to the first terminal, while the drain terminal is connected to the second and third terminals. The frequency converter further includes a trap circuit, which resonates at a frequency of a harmonic of the local oscillator signal to substantially eliminate the harmonic.

Abstract: The variable gain amplifier of the present invention includes: an amplifier for amplifying an input signal and outputting the amplified signal; an amplifier output-side switch connected to the output of the amplifier at one terminal, whether the amplifier output-side switch is ON or OFF being controlled with a control voltage; and a low-gain circuit including an attenuator for attenuating an input signal and outputting the attenuated signal, and a first switch connected in series with the attenuator, whether the first switch is ON or OFF being controlled with the control voltage. One terminal of the low-gain circuit is connected to an input of the amplifier while the other terminal is connected to the other terminal of the amplifier output-side switch. During low-gain operation, power supply to the amplifier is stopped, and the first switch is ON and the amplifier output-side switch is OFF according to the control voltage.

Abstract: The present invention provides a frequency conversion circuit capable of reducing current without impairing high frequency characteristics. A local oscillator amplifier is formed of a first field effect transistor. A source thereof is grounded by a first capacitor in terms of high frequency, and a gate thereof is connected to one end of each of first and second resistors. The other end of the first resistor is grounded, and the other end of the second resistor is connected to a voltage supply terminal. An intermediate frequency amplifier is formed of a second field effect transistor. A source thereof is grounded through a third resistor and a second capacitor that are connected in parallel with each other. A drain thereof is connected to an intermediate frequency signal output terminal through a third capacitor and an intermediate frequency output matching circuit. The source of the first field effect transistor and the drain of the second field effect transistor are connected through an AC blocking circuit.

Abstract: In a dual-mode radio telephone transmitter operative in both an analog modulation mode based on the FDMA system and a digital modulation mode based on the TDMA system, a DC bias voltage Vdd to be applied to a power amplification circuit is varied in accordance with the type of modulation, so that the input/output characteristics of the power amplification circuit can be optimized. To this end, a micro processor controls a switch interposed between the power amplification circuit and a positive DC power unit in such a manner that the DC bias voltage Vdd is 4.8 V for the FDMA mode, while the DC bias voltage Vdd is 6.0 V for the TDMA mode. The value of another DC bias voltage Vgg in the power amplification circuit is fixed. The value of the DC bias voltage Vdd is set higher in the TDMA mode than in the FDMA mode; thus, it becomes possible to increase the power added efficiency in the FDMA mode, without adversely affecting high linearity and high efficiency in the TDMA mode.

Abstract: This invention relates to an electrolytic ion water generator for producing alkali ion water containing alkali ions and acid ion water containing acid ions by introducing tap water or the like into an electrolytic cell comprising electrodes and ion exchange membranes arranged alternately which electrolyze the electrolytes in the water.Electrolytic cell unit panels having the same shape are constructed by attaching the electrode plate and ion exchange membrane onto each synthetic resin frame. The electrolytic cell unit panels are layered in a water-tight manner facing the front sides to front sides and the rear sides to rear sides via O-rings. A water-inlet external cover is attached at one end of the layered electrolytic cell unit panels, and a water-outlet external cover is attached at the other end of the layered electrolytic cell unit panels in a water-tight manner to secure the total assembly.