Low noise Piezo stack driver amplifier design

[mawyatt]

Sorbothane

Didn't know what's that, so googled it:



 

Interesting. We've used Sorbothane for years, my Thor Labs based optical imaging setup is supported on Sorbothane feet, but did not know how this material came about.

Thanks for video link 

Best,

[RoGeorge]

To me that was a little surrealistic, with that implanted probe in the scientist's tibia, followed by violent mallet hits over the Dr.'s hand!     Then the NFL professional footballer called to put extra strength into the testing mallet hits.   

Science was rough back then.

Not to mention the cool remote sensor for chemical warfare mentioned in the this same topic only a few posts up:

Back in 1980~84 we worked on the XM21 Remote Sensing Chemical Agent detector. This instrument was based upon a precision Laser Controlled small (handheld) closed loop moving mirror Michelson Interferometer sensing 8-12 microns with a Cryo-Cooled (77K) Mercury-Cadium-Telluride detector. The technique employed was called Remote Sensing Spectral Radiometry, and utilized the atmospheric background minute temperature gradients to create a S-B Blackbody "signature" of the atmosphere which reveled the various aerosol chemicals remotely. From this warfare chemical agents and concentrations could be extracted.

By the way, it is such a delight to read about the incredible levels of performance you mention, and about the most unexpected projects you have been a part of, your projects never cease to amaze!   

[mawyatt]

To me that was a little surrealistic, with that implanted probe in the scientist's tibia, followed by violent mallet hits over the Dr.'s hand!     Then the NFL professional footballer called to put extra strength into the testing mallet hits.   

Science was rough back then.

Yes that was a little dramatic, but got my attention!!

Not to mention the cool remote sensor for chemical warfare mentioned in the this same topic only a few posts up:

Back in 1980~84 we worked on the XM21 Remote Sensing Chemical Agent detector. This instrument was based upon a precision Laser Controlled small (handheld) closed loop moving mirror Michelson Interferometer sensing 8-12 microns with a Cryo-Cooled (77K) Mercury-Cadium-Telluride detector. The technique employed was called Remote Sensing Spectral Radiometry, and utilized the atmospheric background minute temperature gradients to create a S-B Blackbody "signature" of the atmosphere which reveled the various aerosol chemicals remotely. From this warfare chemical agents and concentrations could be extracted.

The X21 project was particularly interesting in that US President Regan's chief science advisor said it was impossible for this technique and instrument to work! We lobbied for a demonstration and proved the technique and instrument did indeed work as described, and the project went on to full production and deployment alerting solders in the battlefield of chemical attacks.

The miniature moving mirror interferometer was a masterpiece of engineering, utilizing flexure pivots for the moving mirror, voice coil motor, HeNe laser based closed loop servo control system,  diamond turned corner cube reflectors, small Split-Cycle Sterling Cryo cooler, an 18 bit ADC was phase-locked clocked with the interferometer position (derived from laser fring counts), thus producing coherent sampling interferograms that suppressed outside influences like vibration, temperature, and aging. All this and you could hold it in your hand

By the way, it is such a delight to read about the incredible levels of performance you mention, and about the most unexpected projects you have been a part of, your projects never cease to amaze!   

Thanks, I'm glad you like them. Wish I could convey more but many are still not for public disclosure
I've been very fortunate to work on some interesting and important projects throughout my career, along side some brilliant engineers/scientist, and thankful for the opportunities.

Best, 

[mawyatt]

Me thinks people don't appreciate how smooth the motion has to be for SPMs. IMO, only single extension and flexure devices need apply. Anything cyclic is going to produce artifacts. For the same reason, even though PZTs are maybe 8-bit devices when it comes to precision, you probably want 16-bits just for smooth motion and to avoid exciting unwanted resonances.

Even tho the piezo elements may not be highly accurate, they do have a continuous analog behavior with non-linear properties. These elements can be located inside a high gain precision closed loop system to produce 16~20 bit resolutions, where the ultimate performance is dictated by the position feedback sensor not the piezo elements. Carefully located precision strain gauge bridges work as do capacitive gauges, for use as precision position sensors. You can usually help dampen these unwanted mechanical resonances with a carefully crafted closed loop system, and agree slow movements certainly work to not excite these mechanical resonances.

Best

[Conrad Hoffman]

Long ago I did a closed loop system. It worked well but you have to be careful that the sensing system doesn't introduce noise! Don't ask how I know that.

[Deef700]

Hi all,

I am new on this great blog. I was triggered by this older topic due to the design discussion of the different piezo drivers, interesting. But what about the asymmetric high voltage power supply (booster ?) Does anybody know for example what design is probably used on the PDU150 for getting the asymmetric high voltage rails include negative value ?

Thanks.
Deef

[dzseki]

Hi all,

I am new on this great blog. I was triggered by this older topic due to the design discussion of the different piezo drivers, interesting. But what about the asymmetric high voltage power supply (booster ?) Does anybody know for example what design is probably used on the PDU150 for getting the asymmetric high voltage rails include negative value ?

Thanks.
Deef

Amplifiers are usually fed from symmetrical power supply voltages, but it is not a necessity, V+ and V- can be anywhere as long as their sum is within the specs of the given device. For the PDU150 I'm quite sure that they are using two DC-DC converters, one to gerenerate the negative supply  eg -15V and an other to generate the high voltage supply, that simple.

[Deef700]

Thanks,
that sounds that easy.
Last question in this case about the power supply, which solutions for the DC converters (high + en low - voltage) should you take when you need  100mA RMS ?

[mawyatt]

When we developed a high voltage piezo driver a number of years ago, these were asymmetrical waveform ranges and shouldn't be allowed to go very negative, and were for precision nanometer positioning devices from these folks:

https://www.pi-usa.us/en/products

So the + high voltage was created with a simple low current boost regulator from +12VDC to ~200VDC, and the negative was low current scavenged at ~ -30VDC.

Later we needed a HV AWG amplifier buffer amplifier, and required both + and - HV supply (+-175VDC), so we used the same technique of scavenging the negative voltage but at equal magnitude and current level as the + HV supply.

So a simple boost converter and scavenged negative supply worked well for our needs.

Best,

[Deef700]

Thanks, interesting !
For building a prototype I am first of all trying to find and buy these boost converter and inverted buck boost converter now to get the required 150VDC and -30VDC. Some off the shelf solution for a first test will be helpful. I think both voltages needs to be quite stable as it is starting point for fine positioning of piezo stack.

Later on I will make an own design, already looking to components like the LTC3863 for the negative side for example.

Best regards
Deef

[Deef700]

Hi

I have seen Analog Devices has a lot of more nice DC/DC switching converter chips. Anybody experience with these to create the required asymmetric -30VDC/150VDC ?

Thanks !