Semiconductor device

摘要

The disclosed invention is intended to adjust the driving power of an oscillation circuit to be optimal with a simple circuit configuration. A chip includes an oscillation circuit, an amplifier, an effective value measuring circuit, and a control unit. The oscillation circuit includes an inverting amplifier and a resistor coupled in parallel to the inverting amplifier. The oscillation circuit in which the inverting amplifier is coupled to a crystal oscillator outside the chip generates an oscillation circuit by driving the crystal oscillator. The effective value measuring circuit measures an effective value of an oscillation signal produced by the oscillation circuit. The control unit controls the gain of the inverting amplifier so that the effective value will be equal to a target voltage.

主权项

1. A semiconductor device comprising:
an oscillation circuit including an inverting amplifier whose input terminal and output terminal are coupled, respectively, to an output side and an input side of a crystal oscillator, and produces a voltage at the output terminal as an oscillation signal; an effective value measuring circuit measuring an effective value of the oscillation signal; and a control unit adjusting gain of the inverting amplifier so that the effective value measured by the effective value measuring circuit will be equal to a target voltage, wherein the control unit determines a difference between the effective value and a reference voltage, generates a digital difference value based on the difference, and controls the inverting amplifier based on a comparison of the digital difference value to a target digital difference value.