VitalSigns Digital Stethoscope turn-key IC- VSA-0X

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VitalSigns Digital Stethoscope turn-key IC- VSA-0X

December 27, 2017 Uncategorized 0

The digital stethoscope is a electrical device that used by doctors to hear the sound from our body.

Conventional circuit  of digital stethoscope is pretty complicated.

There are plenty of functions a big LCD, multi-level of filters.

To accomplish the goal of a digital stethoscope usually need a  luxury circuit design (FIG.1)

This circuit comes from synopsys.

It is a good demonstration for current digital stethoscope design that includes

power management IC,

ECM microphone,

audio codecs, and  kinds of amplifier.


To simplified it, we can find some other simpler circuit (FIG.2).

it put a ECM microphone in the rubber sleeve and amplified around 20 times with an OP (U1a).

After amplified, the audio signal goes through a low pass filter of Sallen-key structure (U1b).

The last step do a signal buffer operation (U5) to drive the headphones.

For the above circuit, we can find several topics to discuss:

(1) ECM microphone v.s. MEMS microphone

As we know, ECM microphone introduce more noise than the MEMS microphone.

Besides, the size of ECM microphone is much bigger than MEMS microphone.

About the power consumption, it takes around 20~50 times power than MEMS type.

For size , power and noise level, ECM microphone is not a good solution for digital stethoscope design.


(2) Complex power module

In order to deal with the pre-amplifier. It needs a +/- 9V power to drive the OP with a big data swing.

It is not a good choice for the circuit design, because it makes the battery selection, charging and power stage design difficult.

(3) Big circuit size

The circuit needs 4 parts. ECM microphone in the sleeve and pre-amplifier, low pass filter and a headphone drive.

The other problem is we shall put the ECM microphone into the rubber sleeve. It might introduce more noise problems.

It is impossible to fit all the circuit into the conventional stethoscope.

VitalSigns Technology provides an turn-key solution to make all circuit above into a stethoscope with a powerful chip named VSA-01 / VSA-02.

VSA-0X is a great stethoscope front-end IC.

It makes the design of a digital stethoscope easy.

The chip has built in a MEMS microphone pre-amplifier and headphone driver.

All you need to do is connect the power and MEMS microphone.


The chip size of VSA-0X is around 4 mm x 4 mm  and all the application circuit  can be fit in the stethoscope bell structure.

The noise level is mere 1/20 of the conventional OP type pre-amplifier circuit.

The application circuit is simple and effective.

If you want to make it a wireless stethoscope, that only needs to add a WIFI or Bluetooth module and connect the OUT signal to a 12-bit SAR-ADC channel.

All the audio data can be sent the software and heard in the cloud.

Please contact us for the stethoscope turn-key IC VSA-0X .



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