Semiconductor device and ultrasonic diagnostic apparatus using the same
The present invention provides a semiconductor device of a bi-directional analog switch having a high linearity and a low electric power loss. An ultrasonic diagnostic apparatus having a high degree of detection accuracy, comprising the semiconductor device, is also provided. A semiconductor device of a bi-directional analog switch, comprising a switch circuit capable of switching ON or OFF bi-directionally, and built-in driving circuits for the switch circuit, wherein the driving circuit is connected to first and second power supplies, and a first power supply voltage is higher than a maximum voltage of a signal applied to an input/output terminal of the switch circuit, a second power supply voltage is lower than a minimum voltage of a signal applied to an input/output terminal of the switch circuit, and the driving circuit comprises a Zener diode and a p-type MOSFET connected in series between the first power supply and the switch circuit.
1. A semiconductor device comprising:
a switch circuit capable of switching ON or switching OFF, bi-directionally; and
a driving circuit for driving the switch circuit,
wherein,
the driving circuit is connected to a first power supply comprising a first power supply voltage which is equal to or higher than a maximum voltage of a signal applied to a first terminal comprising an input or output terminal of the switch circuit, and the driving circuit is connected to a second power supply comprising a second power supply voltage which is equal to or lower than a minimum voltage of a signal applied to a second terminal comprising an input or output terminal of the switch circuit; and
the driving circuit comprises a Zener diode and a p-type MOSFET connected in series between the first power supply and the switch circuit.
2. A semiconductor device as claimed in claim 1 , further comprising a level-shift control circuit for level-shifting a switch control signal to control the driving circuit.
3. A semiconductor device as claimed in claim 2 , wherein the driving circuit comprising the Zener diode and the p-type MOSFET, the switch circuit, and the level-shift control circuit are formed in a common manufacturing process and within a same substrate.
4. A semiconductor device as claimed in claim 1 , wherein a Zener voltage of the Zener diode is equal to or higher than a threshold voltage of an n-type MOSFET of the switch circuit.
5. A semiconductor device as claimed in claim 1 , wherein the switch circuit is a bi-directional analog switch circuit for
connecting source terminals of two of n-type MOSFETs each other; and
connecting gate terminals of two of n-type MOSFETs each other.
6. An ultrasonic diagnostic apparatus, wherein the semiconductor device as claimed in claim 1 is utilized for
switching a wave-transmission of an ultrasonic signal to an oscillator,
separation-switching a wave-transmission pulse generator and a reception amplifier of the ultrasonic signal; or
switching a probe.