Variable capacitance element and high-frequency device

摘要

A high-frequency device includes an antenna coil, a variable capacitance element, and an RFIC. The variable capacitance element is configured by capacitor units in each of which a ferroelectric film is sandwiched between capacitor electrodes, and a capacitance value changes according to a control voltage applied between the capacitor electrodes. A control voltage application circuit configured by a plurality of resistance elements of different resistance values, and a resistance element of the variable capacitance element unit configured to apply a control voltage to the variable capacitance element are arranged in a layered manner above the capacitor unit. Thus, a variable capacitance element and a high-frequency device that includes a control voltage application circuit eliminating problems such as distortion due to active elements and growing IC size along with complication of circuit architecture, and ensuring reliability on impact due to falling or the like, are provided.

主权项

1. A high-frequency device comprising:
an antenna coil; a variable capacitance element configured to change a resonant frequency of an antenna circuit including the antenna coil; and an RFIC connected to the variable capacitance element; wherein the variable capacitance element includes:
ferroelectric capacitors each configured such that a ferroelectric film is sandwiched between capacitor electrodes and such that a capacitance value changes according to a value of a control voltage applied between the capacitor electrodes; anda control voltage application circuit including a resistance voltage divider circuit including a plurality of resistance elements having different resistance values and configured to apply a control voltage to the variable capacitance element; the variable capacitance element is provided on a substrate and made of a thin film material, and the plurality of resistance elements are provided on the substrate in one layer; the variable capacitance element is provided in a single integrated circuit; and the one layer of the plurality of resistance elements is provided on top of a layer including the ferroelectric film.