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i need help with ultrasound receiver circuit???

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ironjaycuttler

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ultrasound circuit

Hello well i'm trying to build a receiver circuit for one frequency 2 Mhz (echo) but i need two circuits a Rf tuning amplifier and one demodulator my question is if i can build this with Opams or i need circuit tank with transistors or if somebody have circuit receiver for medical aplications i really like some help coz i don't have nothig regardsss for everybody!!!! :D
 

algilsan

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ultrasound receiver

I don't have clear a question, ultrasonics like you said are in the range of 44KHz, so a 5MHz signal it's not this kind.

If you want to receive 5MHz signals first you need to use a transductor for this signals. So you will need an antenna, you can make a dipole yourself, it's easy. then you would need to use resonant circuit to get 5MHz signals. Like are low Freq signals, you can, attach anntena directly to your OA.(but remenber to keep cable distance between antenna an OA as low as possible to minimize losses and reflections, keep input impedance of OA equal to impedance od antenna (usually 50 ohms), then make an OA configuration than include a 5MHz band pass filter centered at this freq. Amplifie this signal with another OA (most commonly OA's have freq range up to 10Mhz, but you have to limite gain). and finally you have your signal

regards
 

echo47

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ultrasound receiver circuit

You didn't say your transducer characteristics, or your bandwidth, or your modulation type, or your required gain, or your power requirements, or ...

Maybe try something like this:

1. FET source-follower input stage (your 2 MHz acoustic transducer probably has low capacitance and high impedance).
2. NPN common-emitter pre-amp stage with LC tuned collector.
3. Analog Devices AD600 gain stage(s), perhaps with LC bandpass filters between stages.
4. Two sampling A/D converters, operated 90-degrees apart to achieve approximate/cheap quadrature sampling. Your sample rate must be higher than your bandwidth to avoid aliasing. This is decimation sampling.
5. DSP chip to do your precision bandpass filtering and demodulation.

Good luck! Tomorrow we build a simple rocket that flies to Mars. :)
 

ironjaycuttler

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ultrasonic receiver circuit

Thanks for your comments!!! Well I try to explain well the work that I want make is about Doppler Ultrasound blood flow detector the type of transducer that I will operate is 2.2 Mhz I have the circuit transmitter is one oscillator that operate 2 Mhz I leave 200 KHz for I can’t damage the crystal of course by frequency, I have problem with receiver circuit coz I have one circuit is a transistor (BC347C) the configuration is common divisor in the collector I have a circuit tank (it amplifies the signal of interest and discriminates other signals), this circuit tank I will use the resonance frequency fr = 1/(2pi*(LC)^1/2)) where L = 63.32 uH and C = 100 pF so my question is if I can use Opams or maybe another circuit that can be more efficient than this, that’s for your help I I hope this can help another peoples too!!! 8O

 

algilsan

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building a ultrasound receiver

As you said, your receiver circuit is a tunned amplificator made by one transistor. So you can use operational amplifiers instead since you are working with freqs not much high. Search for filters design with op amps, like T filters, or something like this. But you must remember, if you use standard op amps you must to limitate gain.

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ironjaycuttler

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bandwidth of ultrasound receiver

Yes u have right i'm using a tunning amplifier!!!! 8) and if i want use amplifier like a filter i will have in consideration like u said take u :eek:

 

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