Abstract: The present invention provides an oscillation circuit which enables a further decrease of power consumption. The oscillation circuit comprises a piezoelectric oscillator, such as a quartz oscillator, for generating voltage that oscillates at a natural frequency, an inverter for amplifying this oscillation voltage, a Schmitt trigger circuit for shaping the waveform of the output of the inverter and outputting oscillation output signals, and a constant current source which is connected to a power supply line from a battery and supplies current to the power supply of the inverter and the Schmitt trigger circuit.

Abstract: The present invention provides a transceiver apparatus that permits miniaturization even when the antenna thereof is an unbalanced circuit and the transmitter circuit section and receiver circuit section thereof are balanced circuits. The transceiver apparatus is constituted comprising: a semiconductor integrated circuit device that mounts on the same semiconductor chip a balanced receiver circuit 41 for receiving a received signal as a differential input and balanced transmitter circuit 52 for outputting a transmitted signal as a differential output, and that has at least two terminals 71,72 connected to connecting nodes that connect the balanced receiver circuit 41 and the balanced transmitter circuit 52; first and second capacitors C2,C3 connected to the terminals 71, 72 respectively; an external inductor L1 connected to the first and second capacitors C2, C3; a band pass filter 2 and an antenna 1 coupled to the first capacitor C2; and a third capacitor C1 connected to the second capacitor C3.

Abstract: The present invention provides an oscillation circuit which enables a further decrease of power consumption. The oscillation circuit comprises a piezoelectric oscillator, such as a quartz oscillator, for generating voltage that oscillates at a natural frequency, an inverter for amplifying this oscillation voltage, a Schmitt trigger circuit for shaping the waveform of the output of the inverter and outputting oscillation output signals, and a constant current source which is connected to a power supply line from a battery and supplies current to the power supply of the inverter and the Schmitt trigger circuit.

Abstract: The present invention provides a transceiver apparatus that permits miniaturization even when the antenna thereof is an unbalanced circuit and the transmitter circuit section and receiver circuit section thereof are balanced circuits.

Abstract: A conventional receiver system has a filter circuit with unsatisfactory gain characteristics, and thus does not offer satisfactory reception performance. A receiver system of the invention has a filter circuit employing an equivalent inductor circuit including a capacitor, a gyrator composed of a plurality of operational transconductance amplifiers and having the capacitor as a load, and a resistor connected in series with the capacitor. A conventional receiver system has a band-pass filter circuit with a low third-order input intercept point, and thus does not offer satisfactory reception performance.

Abstract: A frequency modulating (FM) transmitter includes a reference frequency generator, a reference frequency divider, a stereo modulation circuit, an oscillator circuit, a program counter, and a PLL frequency synthesizer. The reference frequency generator is for generating a reference frequency. The reference frequency divider is for frequency dividing the reference frequency. The stereo modulation circuit is for frequency modulating audio signals by using one output of the reference frequency divider to supply resultant stereo modulated signals as FM signals. The oscillator circuit is for generating carrier waves to transmit the FM signals. The program counter is for frequency dividing the carrier waves into variable frequency components. The PLL frequency synthesizer has a phase comparator circuit for comparing the variable frequency components output from the program counter with another output of the reference frequency divider.

Abstract: The receiver includes a ceramic filter which is connected to the output side of a mixer circuit for limiting a band, an intermediate frequency amplifying circuit cascade connected to the output side of the ceramic filter in a plurality of intermediate frequency amplifying stages, and a plurality of passive band-pass filters connected between the respective intermediate frequency amplifying stages of the intermediate frequency amplifying circuit. Thereby, the receiver is able to reduce the size and costs thereof.