Patent ID: 11921241
Assignee: FUJIFILM HEALTHCARE CORPORATION
Field: Medical technology (Instruments)
Classification: CPC B  G  A | IPC G

Claim 6:
7. An ultrasonic probe transmitting an ultrasonic wave to a diagnostic organ and receiving a reception signal that is a reflected wave, the ultrasonic probe comprising:
a plurality of transducers;
a plurality of low-noise amplifier circuits individually corresponding to the plurality of transducers, wherein each of the plurality of low-noise amplifier circuits has a variable resistor negative feedback unit making a resistance value variable by a voltage signal inputted to a control terminal of the variable resistor negative feedback unit; and
a control circuit,
wherein the control circuit includes:
a dummy circuit generating a bias voltage of the variable resistor negative feedback unit in each of the plurality of the low-noise amplifier circuits; and
an adding circuit outputting an added signal generated by adding the bias voltage from the dummy circuit and a control signal increasing or decreasing with a lapse of time, and wherein
each of the plurality of low-noise amplifier circuits input an output of the adding circuit to the control terminal of the variable resistor negative feedback unit to perform variable control on a gain of the low-noise amplifier circuit,
the low-noise amplifier circuit is an inverter circuit having a first P-channel field effect transistor connected in series to a first N-channel field effect transistor,
the variable resistor negative feedback unit is a unit having a second N-channel field effect transistor connected in parallel to a second P-channel field effect transistor,
one end of the parallel connection of the second N-channel field effect transistor to the second P-channel field effect transistor is connected to a connecting point of the first P-channel field effect transistor to the first N-channel field effect transistor, and another end of the parallel connection is connected to gates of the first P-channel field effect transistor and the first N-channel field effect transistor,
a first added signal which is an output of the adding circuit outputting a sum of the bias voltage from the dummy circuit and a first control signal increasing or decreasing with a lapse of time and whose level is shifted by a gate-to-source voltage of a third N-channel field effect transistor is connected to a gate terminal of the second N-channel field effect transistor of the low-noise amplifier circuit,
a second added signal which is an output of the adding circuit outputting a sum of the bias voltage from the dummy circuit and a second control signal having a slope inverted to the first control signal with a lapse of time and whose level is shifted by a gate-to-source voltage of a third P-channel field effect transistor is connected to a gate terminal of the second P-channel field effect transistor of the low-noise amplifier circuit, and
by these connections, the gain of the low-noise amplifier circuit is variably controlled.