1. Field of the Invention
The present invention relates to a semiconductor device. In particular, the present invention relates to a semiconductor device functioning as a driver circuit for driving a power device for power supply.
2. Description of the Related Art
A power device is an element used to drive a load such as a motor. The power device can control supply of a large current to a load to perform the supply intermittently by a switching operation.
As an example of the power device, a power transistor such as an insulated gate bipolar transistor (IGBT) can be given. The power transistor has a large gate capacitance compared to other transistors.
Driving of the power transistor is controlled by pulse width modulation (PWM). PWM control is performed in accordance with a PWM signal output from a microcomputer or the like. The voltage of the PWM signal is too low to directly drive the power transistor having a large gate capacitance. Therefore, the PWM signal needs to be converted into a high-voltage signal and supplied to the power transistor.
A driver circuit for converting the PWM signal to a high-voltage signal includes a transistor including silicon. For example, Patent Document 1 discloses a structure of a semiconductor device in which an n-channel transistor and a p-channel transistor are provided over a silicon substrate and the on/off state of IGBT is controlled.