Patent ID: 7791423

Claim:
In a two-frequency switchover type crystal oscillator in which first and second IC chips are connected to common wiring patterns of a circuit substrate and to first and second crystal resonators to form first and second oscillation circuits, and said first and second oscillation circuits are selectively operated in accordance with a selection mechanism; a two-frequency switchover type crystal oscillator in which surfaces opposite to circuit function surfaces of said first and second IC chips are connected to form a two-stage structure; IC terminals of the circuit function surface of said first IC chip are directly connected both electrically and mechanically to said wiring patterns; and IC terminals of the circuit function surface of said second IC chip are connected electrically by wire bonding to said wiring patterns; wherein those wiring patterns of said wiring patterns that are connected to power source, output, and ground terminals of said first and second IC chips are connected in common with respect to said first and second oscillation circuits, wherein said power source, said output and said ground terminal of said first IC chip are directly connected both electrically and mechanically to said wiring pattern of said power source, said output and said ground terminal, wherein said power source, said output and said ground terminal of said second IC chip are connected electrically by wire bonding to said common wiring pattern of said power source, said output and said ground terminal, and wherein said selection mechanism is formed of an inverter element that inverts an external signal between input and output sides thereof and switching elements that are connected between the input and output sides of said inverter element.