JP4940120B2 - High voltage analog switch IC - Google Patents

Description

  The present invention relates to a high-voltage analog switch IC, and more particularly to a high-voltage analog switch IC used in an ultrasonic diagnostic apparatus that transmits an ultrasonic signal to a subject and receives reflected waves to obtain internal information of the subject.

  An ultrasonic diagnostic apparatus transmits an ultrasonic signal by applying a probe containing an ultrasonic transducer, which is a piezoelectric element, to a subject, receives a reflected wave, performs image processing, and generates an ultrasonic tomographic image. To get.

  In the electronic scan type ultrasonic diagnostic apparatus, a high voltage analog switch IC is used as a switch for switching an ultrasonic transducer because a transmission pulse has a high voltage.

  The configuration and operation of the conventional example will be described with reference to FIG.

FIG. 7 is a block diagram showing an example of an ultrasonic diagnostic apparatus. As shown in the figure, the ultrasonic diagnostic apparatus 1 is roughly composed of an apparatus main body 2 and an ultrasonic probe 3 for direct application to a subject. The apparatus body 2 includes a transmission circuit 4, a reception circuit 9, and a limiter 10, which are ultrasonic vibrations provided to the ultrasonic probe 3 via the signal line 6, the control circuit 7, and high-voltage analog switches 5 a to 5 h. It is connected to the child 8. The ultrasonic probe 3 is usually composed of an ultrasonic transducer 8 having about 60 to 200 elements. High-voltage analog switch IC corresponding number of, i.e. fraction IC obtained by dividing the number of ultrasonic transducers in the number of channels per 1IC are used to it.

  The control circuit 7 selects a plurality of channels among the high withstand voltage analog switches 5 a to 5 h and turns them on, and the transmission circuit 4 and the selected ultrasonic transducer and reception circuit 9 are brought into conduction by the signal line 6 during that period. Become. Meanwhile, a high-voltage pulse signal is input from the transmission circuit 4 and applied to the selected ultrasonic transducer through the selected high-voltage analog switch. The ultrasonic transducer selected at this time converts the electrical signal into an ultrasonic signal and transmits the ultrasonic signal to the subject. In the subject, a reflected wave is generated and returned to the selected ultrasonic transducer, converted into an electrical signal, and input to the receiving circuit 9 through the limiter 10 as a received signal. Here, the limiter 10 serves to pass only the received signal without passing the high-voltage pulse signal of the transmission circuit 4. Next, the control circuit 7 selects another plurality of channels and performs the same operation as described above. The switching of the high voltage analog switch is performed sequentially. Although omitted in FIG. 7, the received signal returned to the receiving circuit 9 is amplified and subjected to image processing, and is displayed on a screen provided in the apparatus main body as an ultrasonic diagnostic image.

  Existing products of high withstand voltage analog switch ICs include those with 8 channels to 16 channels. For the purpose of reducing the size of an ultrasonic device, there is a high withstand voltage analog switch IC of a type incorporating a bleeder resistor for discharging surplus charges of an ultrasonic transducer. FIG. 8 is a block diagram of a high withstand voltage analog switch IC incorporating a bleeder resistor, and FIG. 9 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus in a state where a plurality of them are connected.

  The function of this IC will be briefly described with reference to FIG. This example shows an example in which an 8-channel output switch is incorporated. The output of the output switch 15 is controlled by the shift register 12 and the latch 13. The output switch is composed of a high withstand voltage analog switch having a rating of 220 V because of the necessity of passing a high voltage pulse signal. The level shifter 14 is responsible for converting the control signal into a high voltage analog switch drive signal. The bleeder resistor 16 is connected to both of the output terminals 17a and 17b of the high withstand voltage analog switch, and can be grounded externally by the RGND terminal 18. In the IC having the configuration shown in FIG. 8, since the output switch 15 is a bidirectional switch, the bleeder resistor 16 is provided at both the output terminals 17a and 17b. FIG. 9 shows the configuration of the ultrasonic diagnostic apparatus when a plurality of analog switch ICs are connected at this time.

JP-A-8-131440 JP 2006-87602 A

  In the IC having the configuration shown in FIG. 8, since the output switch 15 is a bidirectional switch, the bleeder resistor 16 is provided at both the output terminals 17a and 17b. FIG. 9 shows the configuration of the ultrasonic diagnostic apparatus when a plurality of analog switch ICs are connected at this time. Since the bleeder resistor 16 is on both sides of the output switch, not only the piezoelectric element side but also the signal transmission circuit It will also be added to the 4th side. When viewed from the transmission circuit 4 side, the bleeder resistors 16 are connected in parallel for the number of channels. For this reason, there is a problem that the high-voltage pulse signal sent from the transmission circuit is lost as current consumption by the bleeder resistance before passing through the analog switch.

  The present invention has been made in view of the above-mentioned points. The object of the present invention is to solve the above-mentioned problems, and when a user designs a printed circuit board pattern, the bleeder resistance is originally a necessary load. It is an object of the present invention to provide a high withstand voltage analog switch IC in which an IC internal bleeder resistance is set to one element per channel so that it can be connected to only one, and a pad arrangement and a surface mount type package terminal are devised.

  In order to achieve the above object, the high voltage analog switch IC of the present invention is used in an electronic scanning ultrasonic diagnostic apparatus having a plurality of ultrasonic transducers, and drives a plurality of high voltage analog switch output units. And a bleeder resistance terminal that is independent of the high-voltage analog switch output terminal, in a high-voltage analog switch IC that includes a control circuit that performs external charge addition and a bleeder resistance for discharging an extra charge that is integrated on one chip. It is characterized by having. In other words, one bleeder resistor is provided for each channel in the IC, and a bleeder resistor terminal that is independent from one of the output terminals corresponding to each channel output switch element and the other of the output terminals is provided. In this case, a bleeder resistor can be arbitrarily connected only to the piezoelectric element side.

  According to the present invention, since the bleeder resistor can be connected only to the piezoelectric element side that is a load in the ultrasonic diagnostic apparatus using the high-breakdown-voltage analog switch IC with a built-in bleeder resistor, the high-voltage pulse signal from the transmission circuit is connected to the analog switch. It is possible to transmit efficiently without being attenuated on the front side.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a high voltage analog switch IC of the present embodiment. As shown in the figure, a new independent terminal 22 separated from the analog switch output terminals 17a, 17b is provided with one bleeder resistor for each channel.

  FIG. 2 shows an ultrasonic diagnostic apparatus in which a plurality of high voltage analog switch ICs of this embodiment are connected. Except for the piezoelectric element and the transmission circuit section, they are omitted. By separating the bleeder resistor from the analog switch output terminal and providing an independent terminal, the bleeder resistor is provided only on the analog switch output terminal side corresponding to the piezoelectric element side on the printed circuit board on which the IC is mounted as shown in FIG. Can be connected. Since the bleeder resistor is not connected to the transmission circuit 4 side, the high voltage pulse signal can be transmitted to the piezoelectric element side as a load without being attenuated.

  FIG. 3 is a chip plan view showing an output portion of the high voltage analog switch IC of the present embodiment shown in FIG. 2, and FIG. 4 is a schematic diagram showing a state in which the IC chip 31 is wire bonded.

  In the block diagram of this embodiment, the output is composed of 8 channels, but FIG. 3 shows one of them, and the remaining channels are the same and are omitted. Since this IC requires a plurality of output elements that require a high breakdown voltage, an IC having an element isolation structure based on dielectric isolation is used. However, even if pn junction isolation or SOI (Silicon on Insulator) isolation technology is used. good. The areas of the analog output switch of the IC chip 31 are indicated by 32a and 33a. In this example, MOSFETs 32b and 33b are used. Since it is a bidirectional switch, the source of 32b is the same as the source of 33b, and the drain of 32b and the drain of 33b are connected to the output pads 34 and 35, respectively. On the other hand, the bleeder resistor 36 is connected to the pad 37 on one side and to the RGND terminal on the other side by wiring. The output terminal is connected to the inner leads 39a and 41a with a wire 38, sealed with resin 30, the outer lead 39b is one terminal of the output, the outer lead 41b is the other terminal of the output, and the bleeder resistance with the outer loop 40 being independent. Terminal.

  FIG. 4 shows a cross-sectional structure of the IC portion of FIG. In this embodiment, an example of mounting on a surface mounting type package is shown. FIG. 5 shows an example in which this IC is mounted on a print pattern. An analog switch output corresponding to one channel is shown, and the other channel portions are the same and are omitted. As shown in FIG. 5, when the output terminal 40b of the bleeder resistor is independent of the high withstand voltage analog switch output terminal 39b or 41b, the printed pattern 43a is selected on the ultrasonic transducer side as a load. By connecting the outer lead 39b and 40b of the analog switch IC 31 to a common pattern and connecting the other analog switch output terminal 41b to the pattern 43b selected as the transmission circuit side, the bleeder resistance is an ultrasonic vibration that is a load. Can be connected only to the child side. When the 41b side is selected as the ultrasonic transducer side, the printed circuit board pattern may be reversed.

  In this embodiment, an example of an 8-channel multi-output high withstand voltage analog switch IC is shown. However, a high withstand voltage analog switch IC with a plurality of channels, for example, 4 channels and 16 channels may be used. In this embodiment, the output device is a high breakdown voltage N-channel MOSFET, but may be a high breakdown voltage P-channel MOS or a bipolar transistor.

  FIG. 6 is a plan view of an IC chip showing a second embodiment of the present invention. As in FIG. 3, only one analog switch output channel is shown. In this embodiment, two bleeder resistors are provided per channel, and are arranged in the IC chip so that the bleeder resistors 36a and 36b are connected in parallel by wire bonding and can be connected to the inner lead 40a. In this way, it is possible to select the case where only one of the bleeder resistors 36a or 36b is connected to the inner lead 30a or the case where both are connected. In addition, an IC having a resistance value of 1 / 2R and two types of versions can be obtained. If the resistance values of the bleeder resistors 36a and 36b are not the same, it is possible to set a desired resistance value in two parallels. Thereby, even if there is a need for a different value depending on the user for the bleeder resistance value, this embodiment can flexibly cope with them. In this embodiment, the selection is made by wire bonding, but it can also be realized by preparing two types of masks only for the process in the electrode process (for example, AL) on the chip.

It is a block diagram which shows the high voltage | pressure-resistant analog switch IC of Example 1 of this invention. 1 is a configuration diagram illustrating an ultrasonic diagnostic apparatus in which a plurality of high-breakdown-voltage analog switch ICs according to Example 1 of the present invention are connected. 1 is an IC configuration diagram for one channel showing a high voltage analog switch IC of Example 1 of the present invention. It is sectional drawing of the IC part shown in FIG. FIG. 5 is a diagram showing an example in which the IC shown in FIGS. 3 and 4 is mounted on a print pattern. It is IC block diagram for 1 channel which shows Example 2 of this invention. It is a block diagram which shows an example of the conventional ultrasonic diagnostic apparatus. It is a block diagram which shows the high voltage | pressure-resistant analog switch IC which incorporated the conventional bleeder resistance. It is a block diagram which shows the structure of the ultrasonic diagnosing device of the state which connected the multiple high voltage | pressure-resistant analog switch IC of FIG.

Explanation of symbols

1, 2, 3 Ultrasonic diagnostic device 4 Transmitter circuits 5a to 5h High-voltage analog switch 6 Signal line 7 Control circuit 8 Ultrasonic transducer 9 Receiver circuit 10 Limiters 11, 21 High-voltage analog switch IC
12 shift register 13 latch 14 level shifter 15 output switch 16 bleeder resistor 17 output terminal 18 RGND terminal 22 bleeder resistor terminal 30 resin 31 high voltage analog switch IC chips 32a, 32b, 33a, 33b output MOSFET
34, 35 Analog output pads 36, 36a, 36b Bleeder resistors 37, 37a, 37b Bleeder resistor pads 38 Wires 39a, 40a, 41a Inner leads 39b, 40b, 41b Outer leads 42 IC tabs 43a, 43b Print pattern

Claims (5)

Used in electronic scanning ultrasonic diagnostic equipment with multiple ultrasonic transducers, equipped with multiple high-voltage analog switch output units, a control circuit that drives them, and a bleeder resistor for extra charge discharge externally added In a high voltage analog switch IC that integrates them on a single chip,
A high withstand voltage analog switch IC comprising a bleeder resistance terminal independent of the high withstand voltage analog switch output terminal. In the high voltage analog switch IC according to claim 1,
The output switch is a bidirectional switch, and each channel has two output terminals. Each bleeder resistor terminal is connected to one of the two output terminals depending on the board pattern. High withstand voltage analog switch IC characterized in that can be selected. In the high voltage analog switch IC according to claim 1,
The high withstand voltage analog switch IC, wherein the plurality of high withstand voltage analog switches include pads for independent bleeder resistors for a plurality of output channels. In the high voltage analog switch IC according to claim 1,
The plurality of high withstand voltage analog switches include independent bleeder resistors twice as many as the number of output channels and the corresponding number of pads. By wire bonding, one or more bleeder resistors per channel are provided. A high withstand voltage analog switch IC characterized by being able to select two parallel connections. 3. A high voltage analog switch IC according to claim 1 or 2, wherein the high voltage analog switch IC is packaged in a surface mount package .

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