Fujitsu Corporation

Fujitsu Vlsi Limited

Tsuyoshi Moribe

Kazuyoshi Arimura

Susumu Kato

Masahiro Yamamoto

Takehito Doi

Mayo Kitano

Masaki Kishi

Kiyoshi Matsuo

Yoshiharu Kamiya

Hideki Sumi

To present a variable capacity circuit and a control method of variable capacity capable of extending a variable capacity width of a variable capacity element to a maximum extent without increasing an element area of the variable capacity element or varying the level of control voltage, a variable capacity circuitcomprises a capacity value control circuitvaractors VAand VAand resistance elements Rand RThe capacity value control circuitissues a variable output voltage CNTOUT depending on input control voltage VT, and controls the potentials at both ends of the varactors simultaneously. The output voltage CNTOUT is variably adjusted so as to have a negative correlation to the control voltage VT. Variable width of terminal voltage VD can be extended from a variable width SAto a variable width SA(range is +/&#x2212;(Vcc)). As a result, as shown in, the changeable area of a varactor capacity value CV can be extended from a changeable area CAto a changeable area CA

Variable capacity circuit and control method of variable capacity circuit

Oscillators have capacitors, respectively, whose capacitances change according to an external force and generate first oscillating signals according to the capacitances. Each of the capacitors is disposed, for example, between a substrate and a mass body that is movably disposed to face the substrate and oscillates in a direction perpendicular to the substrate. A detecting unit detects a relative difference between the capacitances of the capacitors as a difference between frequencies of the first oscillating signals. An angular speed or acceleration applied in a horizontal direction of the substrate is calculated according to the frequency change detected by the detecting unit. Therefore, a capacitance difference detecting circuit and a MEMS sensor that detect a minute change in the capacitances of the two capacitors caused by the external force are formed.

Capacitance difference detecting circuit and MEMS sensor

A phase shift circuit that generates a phase shift signal whose amplitude matches at a plurality of frequencies without increasing the circuit area. The phase shifter circuit includes first and second differential amplifiers which generate first and second first phase shift signals having a first amplitude at a first frequency. A third differential amplifier is connected in parallel to the first differential amplifier. The third differential amplifier generates a third phase shift signal having substantially the same amplitude as the first amplitude at a second frequency. The first differential amplifier is activated in accordance with the first frequency and the third differential amplifier is activated in accordance with the second frequency.

Phase shifter circuit

A semiconductor integrated circuit device includes an orthogonal modulator that maintains carrier leak characteristics regardless of attenuation of an output signal level. The orthogonal modulator includes a phase shifter circuit and generates a modulation signal. An auto gain controller amplifies the modulation signal to generate an amplified modulation signal. A gain adjusting circuit adjusts a gain of the phase shifter circuit in accordance with a control signal.

Semiconductor integrated circuit device with variable gain amplifier

A signal level converter is disclosed, for converting a signal having a first logic voltage swing characteristic to a signal having a second voltage swing characteristic. The converter comprises a level converting section and a differential circuit coupled thereto. The level converting section converts the supplied signal at the first logic voltage swing to an intermediate signal at a logic voltage swing different from the first voltage swing. The differential circuit 3, being supplied with the intermediate signal, produces an output signal at the second voltage swing level that corresponds to the potential difference between a high and low potential power supplies.

Growing community of inventors

Kasugai, Japan

Tsuyoshi Moribe