CRYSTAL OSCILLATION CIRCUIT

摘要

A crystal oscillation circuit capable of reducing the circuit area and performing stable oscillation with a low current consumption. An oscillation amplifier (11) excites a resonance section consisting of a resistor (R1), a crystal oscillator (X1), and capacitors (C1, C2). A constant voltage generation circuit (12) includes a single-stage differential circuit of transistors (M3 to M7) for generating a constant voltage Vreg serving as a power supply voltage of the oscillation amplifier (11) and a capacitor (C3) for suppressing excessive fluctuation of the constant voltage Vreg. Since the single-stage differential circuit generates the constant voltage Vreg, the phase delay of the constant voltage Vreg is not greater than 90 degrees. Accordingly, there is no need of a capacitor for phase compensation and it is possible to reduce the circuit area and obtain stable oscillation with a low current consumption.