Ultrasonic probe and ultrasound diagnostic apparatus
An ultrasound diagnostic apparatus and an ultrasonic probe are provided which are capable of reducing a leak current even in combined use of a low voltage transmission circuit and a high voltage transmission circuit including a buffer. The ultrasonic probe includes: a high voltage transmission circuit for transmitting a relatively high voltage; a low voltage transmission circuit for transmitting a relatively low voltage; and a transducer for selectively receiving a voltage transmitted from the high voltage transmission circuit and the low voltage transmission circuit. The high voltage transmission circuit includes: a current source for varying a current generated thereby and a current drawn thereby based on a set signal; a buffer for driving the transducer in accordance with the currents generated and drawn by the current source; and an impedance controller connected to an input terminal and an output terminal of the buffer.
1. An ultrasonic probe, comprising:
a high voltage transmission circuit for transmitting a relatively high voltage;
a low voltage transmission circuit for transmitting a relatively low voltage; and
a transducer for selectively receiving a voltage transmitted from the high voltage transmission circuit and the low voltage transmission circuit,
wherein the high voltage transmission circuit includes:
a current source for varying a current generated thereby and a current drawn thereby based on a set signal;
a buffer for driving the transducer in accordance with the currents generated and drawn by the current source; and
an impedance connected to an input terminal and an output terminal of the buffer, the impedance being only a resistance connected parallel to the buffer between the input terminal and the output terminal of the buffer.
2. The ultrasonic probe according to claim 1 , wherein
the buffer includes an N-type MOS transistor and a P-type MOS transistor, and
when an output resistance of the N-type MOS transistor and the P-type MOS transistor is ro, and an output impedance of the current source is Zout, a resistance value Rzctl of the resistance is in a range of ro≤Rzctl<<Zout.
3. The ultrasonic probe according to claim 1 , further comprising
a receive circuit for amplifying an echo signal received by the transducer,
wherein a high voltage switch is installed between (i) the transducer and (ii) the low voltage transmission circuit and the receive circuit, and when the voltage is transmitted from the high voltage transmission circuit, the high voltage switch turns off.
4. The ultrasonic probe according to claim 3 , wherein when the voltage is transmitted from the low voltage transmission circuit, the high voltage switch turns on, and the receive circuit turns off.
5. The ultrasonic probe according to claim 3 ,
wherein a low voltage switch is installed between the receive circuit, the high voltage switch and the low voltage transmission circuit, and
when the voltage is transmitted from the low voltage transmission circuit, the low voltage switch turns off.
6. An ultrasound diagnostic apparatus, comprising the ultrasonic probe according to claim 1 .