Hi everyone!
I am currently embarking on a project where I will design an ultrasound device that can Measure both the wall thickness and blood flow speed in the artery. The ultrasound transducers that I will be using resonate at 5Mhz. Therefore I have to produce a 5 MHz wave at a certain voltage to drive the transducer. After doing some reading i designed a Colpitts oscillator circuit at a 5 MHz corner frequency. Here is a model i produced on LT spice.

I understand that this circuit may not produce the most stable 5Mhz waveform, however I am quite committed at this point to make it work. The problem i am coming to is that this waveform needs to be pulsed for the ultrasound imaging to work. I have calculated that it needs to transmit for 0.6 microseconds (3 wave cycles) and then the ultrasound device has to flip to receive for 20 microseconds for all the necessary "echoes" to return.

My questions are:
How do i go about transmitting an receiving for this time? some sort of T/R switch?
What voltage Vpp should i want to amplify my drive signal too? And how would i go about amplifying the signal, an RF amplifier?

Any help would be much appreciated

 

What about your transducers? Will they ring longer than the available time window 600 nanoseconds and 20 microseconds?

What do systems that do something similar do?

 

Isn't it usual to just hit the transducer with a sharp pulse and let it ring at its natural resonant frequency?

 

What about your transducers? Will they ring longer than the available time window 600 nanoseconds and 20 microseconds?

What do systems that do something similar do?

They have backing blocks that stop the resonating for long period of times. I don't actually have a choice in the design of the ultrasound transducer and therefore don't fully know how the backing block works on the transducer.

 

Isn't it usual to just hit the transducer with a sharp pulse and let it ring at its natural resonant frequency?

Does the pulse not have to be a pulse at the resonant frequency, its not as simple as just hitting the transducer with a DC pulse and then letting it ring is it?

 

Hi B3,
Do you have a model type for the transducer?

E
I guess you realise the longer the transducer ringing period it will interfere with any very short range echo's and so limit the shortest measurable range.

 

its not as simple as just hitting the transducer with a DC pulse and then letting it ring is it?

It would be a sharp very narrow pulse. A bit like striking a bell or cymbal. Might not work, though, if the transducer is already heavily damped by the backing block.