[RFC] new EEM: zapper (high-voltage source/PZT driver)

[dtcallcock]

High voltage supplies are commonly required in ion trap experiments. These are widely commercially available but typical models have many of the following drawbacks:

• Noisy output
• Radiated RFI from the box
• Expensive
• Poor stability
• Low channel density
• High power dissipation when voltage output static
• Unnecessarily high current capability (safety issue as well as being the root cause of most of the above)
• Flaky USB connection with high latency

Use cases

Trap electrode voltages

Zotino only provides ±10V. This is generally fine for small high-electrode-density surface traps. However many groups operate larger surface traps or macroscoptic traps of the 'blade' or 'wafer' variety. These typically need much higher voltages, from a few 10s of Volts up to a few hundred Volts. Requirements are basically the same as for Zotino but scaled to higher voltages. The thesis of Chris Ballance has a good discussion of the requirements and a circuit design that could be the basis of this EEM. This type of trap generally has less electrodes so a <32-ch solution may be acceptable.

Slow piezos

We have several piezo-actuated mirrors on our experiment, such as the Thorlabs Polaris K1S2P. These need 0-150V and have a 0.35uF of capacitance. The Thorlabs MDT694B/MDT693B are ubiquitous in our lab but suffer many of the problems described above. For this use case, the new PiezoDrivePD32 may be a good commercial alternative when coupled with a Zotino. I haven't tested one out but we have been happy with other products from PiezoDrive.

Implementation

DAC

16-bit resolution.

A few options:

• Use Zotino. The card would sit next to Zotino and be connected to the IDC headers on it via a ribbon cable(s). Lower risk, less development work, and the Artiq driver would be pretty much for free. Frees up board real estate as no EEM connector etc. would be needed.

• Use an onboard DAC. The 32-ch AD5372 in Zotino has 8-ch (AD5362) and 16-ch (AD5360) equivalents if that is likely to reduce risk/effort. At 4-ch and 8-ch, more accurite, lower noise DACs are available.

Channel Count

This will probably depend a lot on the power consumption, size, and cost of the output stage we decide on. 8 would be a reasonable starting point.

Ranges

Traps generally require a mix of high positive voltages for endcaps (becasue our ions are positively charged) and lower bipolar voltages for other electrodes. There seems to be 2 options for dealing with this:

• Per board range selection. The board could be configured as either single ended or bipolar. If different ranges are required, you just use two boards. The cheaper the board is and the lower the number of the channels, the less of an issue this is.

• Per channel range selection. Board has three supply rails (+V1, +V2 and -V2). Each channel can be changed to run at 0 to +V1 or -V2 to V2 using jumpers or component selection.

Voltages

It would be good to hear from potential users here. As a starting point, how about:

0 to +V1 or -V2 to +V2 where V1= 200, 100, or 50V and V2 = 100, 50 or 25V

Historically some traps have used >1kV but my guess is that there isn't a sensible design that covers that and 10s of volts.

Bandwidth

Zotino has 75kHz analog bandwidth. This sounds like a reasonable starting point.

There should be the option to install components that drastically limit this to say, 100s of Hz.

Stability

Zotino output stage has "Worst-case OpAmp self-heating is about 25C. At 0.2ppm/C, this is 4ppm, which is fine!" This might be harder to achieve at high voltages but <10ppm would be nice.

Connectors

• Individual Front Panel coax connectors - Often slightly less common connectors are used on HV supplies to prevent accidentaly connecting the wrong thing and destroying it. I have seen SMB, SMC, LEMO OO and LEMO 0B used.

• High Density Connector - D-sub etc.

• Both - Same idea as Zotino, where the high density connector can be installed or a ribbon cable run to a panel with individual connectors on it (ie. a BNC-IDC). We could make a version of BNC-IDC with SMB etc. instead.

[hartytp]

This would be greaT. Those yhorlabs boxes are also quite buggy firmware wise.

Nb Chris’s design uses rectified mains so is quite bulky. Iirc the jqi design based on laser printer ics with post regulation would be the way to go here.

Wonder if this could be a poe design with its own dac?

[dtcallcock]

Those yhorlabs boxes are also quite buggy firmware wise.

As far as I can tell, early Thorlabs USB stuff was shipped with the firmware/software still in alpha. It looks like they are phoning it in a bit less these days but I remain to be convinced.

Wonder if this could be a poe design with its own dac?

For trap voltages an EEM connection would be preferable as latency can be a big problem for things you want to change every few shots of an experiment (like a shim voltage).

I'm not against it having its own DAC so that it can be easily 'humpbacked' into a standalone POE device though.

[dtcallcock]

Nb Chris’s design uses rectified mains so is quite bulky. Iirc the jqi design based on laser printer ics with post regulation would be the way to go here.

It looks like the two circuits have fairly comparable noise and tempco specs so either would work. A quick look at the board files for JQI design makes me think we'd struggle to squeeze more than 3-4ch onto a Eurocard (stripped it down to just the DAC and HV section).

PiezoDrive also make a really nice 3-ch driver PDu150. It's only $120/ch and and you could get 9 channels on a board. On the downside you are limited to only one range (-30 to 150V) and we would have to retrofit a different heatsink solution if we wanted to avoid a 12HP board. They also do custom OEM work so once we have a spec it might be worth asking them for a quote.

[dhslichter]

My recollection is that the cheaper PiezoDrive boards used a DRV2700, a bit noisy but a simple way to not have to deal with rolling your own high voltage rails and amplifiers...

[gkasprow]

Long time ago I built piezo driver for AFM. The idea was similar to this approach but the output stage was fully symmetrical (bipolar). Do we care if piezo is driven in differential or single-ended way? Are there some cases where actuator must be grounded?
Single ended drive simplifies the circuit and enables doubling number of channels. But power supply needs to be symmetrical. If we want to use same supply for all channels than it's fine.

About HV supplies. Is good idea to have them as separate module or integrated with piezo driver?
Separate design gives ability to use it as HV source and more flexibility in connection with piezo driver. But is more error-prone.

I've built series of galvanic isolated (10kV) low noise (fully resonant architecture) HV supplies for GEM detectors, but ranges were different (500 to 1.5kV). It can produce positive or negative voltage and has programmable current limit.
This paper describes both my project and HV supply. Here is module schematic.
HVSUP.PDF
This would be probably an overkill for this project. But I plan to move this design to 3U format and use Humpback as a controller. I'm just curious if there would be any application for it in quantum world.

[dhslichter]

I think for most purposes, something like 150-200V is all one needs. In general most of the piezos we deal with are unipolar, and so would want something like 0-150V or 0-200 V. Similarly, for trap voltages one generally wants to have positive voltages on the end cap electrodes. However, one could envision use cases where bipolar output is desired for trap voltages in a number of cases, so I think it would be good to be able to have a bipolar output option.

[hartytp]

3-4ch onto a Eurocard (stripped it down to just the DAC and HV section).

IMO, 4 channels is probably the right number for this design anyway.

[hartytp]

I've had decent experience with the Thorlabs KPZ modules (apart from the firmware being hilariously buggy). While they're not in a form-factor that's as convenient as an EEM, they achieve a decent density, cost and are fairly low power. It would be good to articulate a bit more clearly the reasons why we need to reinvent this wheel rather than using something like KPZs.

[dtcallcock]

I think a simple Eurocard carrier for the PiezoDrive PDu150 would be my preferred non-wheel-reinventing solution.

It's about 5x cheaper and 100x lower noise than the KPZ. It would need to be driven from Zotino/Fastino/Stabilizer (or front panel pot.) but I won't miss the junky Thorlabs firmware.

[gkasprow]

This would occupy at least 16HP. They have smaller moodules like PDu100B
What about other suppliers like E836.

[hartytp]

@dtcallcock fair enough. That makes sense.

Conceptually I like the idea of doing something like the JQI solution (laser printer IC high voltage source with a feedback circuit to reduce the noise/improve the stability). But, while it would be a fun project, I'm put off by the amount of work it would be to get that working really reliably.

Something like a board with a potted module and a microprocessor + ethernet sounds like a decent compromise that could be done with an acceptable level of work. The firmware Greg's student wrote for Thermostat gives one a good base to work from when writing firmware for new projects like this (a lot of the time consuming boiler plate like hooking up ethernet, writing command handlers, etc is already done for one, which is great).

[dtcallcock]

	PDu150	E836
Voltage	-30 to +150V	-30 to +130V
Gain	20	10
Channels	3	1
Cost/Channel	$120	$446
Bandwidth)	180kHz (no load),1 kHz (1uF)	8kHz (no load)
Noise	26uV (0.3Hz-10MHz, 1uF load)	800uV(0-100kHz)
Power supply	24V	24V

This would occupy at least 16HP.

They make a PCB mount version. I asked them for data on that and asked them how to go about switching out the heatsink.

[jordens]

http://www.powerampdesign.net/pad138datasheet.html and the other models might also be interesting.

[sbourdeauducq]

Conceptually I like the idea of doing something like the JQI solution (laser printer IC high voltage source with a feedback circuit to reduce the noise/improve the stability).
But, while it would be a fun project, I'm put off by the amount of work it would be to get that working really reliably.

Were there a lot of problems at JQI? I don't think it's an annoying circuit to get to work well - you don't even need to make your own transformer, and the chips can't have obscure "features".

[dtcallcock]

http://www.powerampdesign.net/pad138datasheet.html and the other models might also be interesting.

I asked for pricing. The quiescent power dissipation (3.2W/ch vs 0.8W/ch for PDu150) and requirement for external power supply are less convenient. The fact it is an op-amp makes it more flexible for driving trap voltages though.

[dtcallcock]

What about other suppliers like E836.

At $446/channel I don't think it's competitive with the PDu150.

[dtcallcock]

I got Altium files for the PCB mount version of the PDU150 and confirmed they can sell it without a heatsink so that we can add our own to make a lower profile (8HP?) card.

[gkasprow]

We would need dedicated 24V power entry. And it should be different than DC jack already used. Maybe we should switch to SMPS modules mounted to the rack rear wall?

[hartytp]

We would need dedicated 24V power entry.

Why not just a 12V->24V SMPS?

[gkasprow]

All depends how much power you want to draw from 24V. We have 5A limit. So you would have max 2A at 24V

[hartytp]

@gkasprow I'd be a bit surprised if a 3 channel unit used more than 60W. 20W per channel seems like a lot. The PDu150 has a peak current of 300mA, so 7.2W which is well below the 60W that our 12V supplies can deliver.

FWIW, I find it really nice to have a big box of 12V PSUs and to be able to power anything in the lab from them...

[gkasprow]

OK, so no problem then. Conversion from 12 to 24V is not an issue either, there are high efficiency synchronous converters that do it nicely

[gkasprow]

For example this one

[hartytp]

Nice! Well, that would definitely be my preference then.

[gkasprow]

Shall such Zapper be controlled over EEM or by Stabilizer?

[hartytp]

Stabilizer

Definitely not by Stabilizer IMO.

Shall such Zapper be controlled over EEM

Having a MSPS DAC controlled by EEM would be my preference. Ethernet control would also be nice but not worth the design complexity IMO.

[dtcallcock]

Stabilizer
Definitely not by Stabilizer IMO.

It will need to be controlled by Stabilizer in some applications (cavity/laser piezo). However I think it would be easier to do this via an analog connection. If so we just need to decide whether to supply a front panel connector or use a header and an internal connection.

[hartytp]

@dtcallcock ack. I hadn't considered that use case.

If so we just need to decide whether to supply a front panel connector or use a header and an internal connection.

Do both like Zotino? Just need to watch out since on the current stabilizer plan we mix both DACs and ADCs onto the same header.

[dtcallcock]

So you would have max 2A at 24V

From PDu150 datasheet: The maximum supply current is 0.9A at full power.

[gkasprow]

well, we can make the SPI interface first, then upgrade the FPGA. The same we will probably do for Fastino.

[gkasprow]

What about the following spec:

• channel count: 8
• low cost Apex amplifiers, PA341DF would be probably fine
• 8 channel AD5362
• at each output, we can install active AC-coupled noise cancellation circuit that can be disabled by the software when the high-speed operation is required. We can use OPTOMOS relays to disable it.
• the operating voltage could be controlled by DIP switches. Negative -50, -100, -200, positive +50, +100, +200 with limitation of 350V with HW protection against opamp damage. DAC references would need to be adjusted as well.
• COTS DC/DC converters
• what about the offset cancellation ADC?
• EEM interface. It can be always controlled by Stabilizer EEM and supplied by its PoE.
• DSUB connector + on-board IDC connector for BNC breakout.
• programmable current limit, per board.

[gkasprow]

By noise cancellation circuit I meant this approach

[gkasprow]

Two such DC/DC converters could do the job. They go down to 90V but could not find others that can be adjusted more than 90...200V

[restelli]

For everyone considering PDu150, the outputs are differential only, NOT single ended, and you cannot ground-reference one output. Thus it won't work for typical piezo actuators where the signal is ground-referenced on one lead.

Neil Pisenti and I a few years ago designed a ground-referenced low noise piezo driver for the JQI strontium lab based of the DRV2700. Despite the DRV2700 being quite noisy by itself we were able to suppress its ripple and obtain noise levels comparable with the best commercial controllers. Noise characterization and overall design are available in our RSI paper: https://arxiv.org/abs/1609.03607

The project is on Github: https://github.com/JQIamo/hv-piezo-driver

The main limitation of the design is that the control bandwidth is limited for large amplitude signals.

[sbourdeauducq]

If we have a lot of bandwidth (1MHz or more), then this circuit can also be useful with EOMs (e.g. https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=2729) for laser intensity stabilization.

[dtcallcock]

Note that the standard drivers for these are +/- 200V, 100mA beasts. If that's what you are after it may be incompatible with (my hope of) something that's higher channel density, lower noise, and lower power consumption than what's already out there.

[sbourdeauducq]

200V * 1MHz * 14pF = 2.8mA. Are the standard drivers able to go much higher than 1MHz, is the 14pF specification inaccurate, or is there something else going on?

[dtcallcock]

Don't forget that coax cable is some 10s of pF/ft.

Still, their driver does seem a bit over-specced. Also somewhat overpriced at $2.6k...

[jordens]

And there is a factor of 2*pi > 6 as well.

[adamkolodynski]

Hello
I have a few questions about the design of this board.

1. Are onboard DAC required? Using Zotino would make it way simpler, and there is always a possibility to add e.g. fast DAC later, in another version.
2. What power supply is available, except the EEM connector?

[dtcallcock]

Hi #adamkolodynski

Are you developing the spec Greg laid out above?

If so:

Are onboard DAC required? Using Zotino would make it way simpler

Sure, but Zotino is quite expensive. Having to add a pricy 32ch card to use this card would be a bit annoying. Using AD5362 (8ch version of AD5372 32ch DAC on Zotino) should allow a lot of Zotino design/code reuse.

there is always a possibility to add e.g. fast DAC later, in another version.

If the analog BW is <100kHz, then the AD5362 should be able to pretty much saturate that. There could also be an IDC input connector on the board and jumpers to disconnect the DAC to allow this.

What power supply is available, except the EEM connector?

If it has DACs on it and power consumption is reasonable then I think just EEM is fine and in line with what's done elsewhere.

[gkasprow]

About the power supply selection, look here

[JakubKajzer]

Does anybody need a noise cancellation circuit in this module?

[adamkolodynski]

After reading the thread about power supply I see some major issues.
Can we use ADHV4702 with -12V and +110V supply, or keep PA341DF?
Is +110V enough range in this use?
ADHV4702 has 20 mA output current, what load we have to drive if we still target 100 kHz?

[sbourdeauducq]

PA341 is "No longer supported for design in" and no longer supplied by DigiKey.
FWIW I've also had a bad experience with an Apex part that was expensive and not performing so well; I would trust ADI more or even a design with discrete BJTs (not so hard to do IME and you can exceed the performance of commercial ICs - but BJTs with the right characteristics can be subject to sourcing problems as well).

[gkasprow]

I'd give an option to adjust the positive HV value.
The negative would be -5V, the positive could be 105 or 205V. The IC requires 2V supply margin.
The power supplies need to have LC filter and LDOs at its outputs.

[gkasprow]

Before you publish the entire schematic, please open separate issues with proposed parts of schematics like decoupling, DAC, supply, etc It will make the feedback faster.

[adamkolodynski]

I started 2 new issues. First about DAC, and second about the power supply, and will probably add another about the output stage.

[gkasprow]

can you please commit the current version of schematics?

[adamkolodynski]

I have a few questions about connectors.
One I assume will be IDC to connect with this IDC-BNC adapter. I don't know the purpose of SCSI power pins(+-13V) here, should I left them floating?
The second will be standard D-SUB connector, and since we don't use differential output just reference to GND and low currents can we use 15 pins D-SUB with 8 signal pins and 7 GND or simply 25 pins D-SUB with 8/8 pins configuration and rest unconnected.
Zapper.pdf

[gkasprow]

I wouldn't use the same connectors as Zotino. Sooner or later someone will mix the two and cause damage.
Just use the D-SUB connector. High-density D-SUBs may not like the 200V range. Just use standard 15pin D-sub. Maybe there are some standard cables available that could be used as they are? If so, it would be nice to follow their pinout...

[adamkolodynski]

I found standard 15 pin D-sub cable and it belongs to GAMEPORT cable(obsolete standard for joystick). Is it worth following this pinout(picture below): signals to analog and digital pins, gnd to gnd and +5V?

There is 3rd option which is VGA connector but it's high-density D-sub. I checked and there are high voltage rated link
About breakout to BNC from DA-15, is it required to create an adapter similar to existing link

[gkasprow]

VGA have some lines shielded, some not, so it is not good idea.
The Gameports cables were attached to joysticks, I'm not sure if one can buy them.
I was thinking about DB15 serial cables like this one

[adamkolodynski]

I meant exactly cable like this, just I found it described as gameport to gameport, anyway they are hard to find, so I will leave pinout like it is now.
I made some minor changes(resistor tolerance, track width, etc.) to the first release. I already asked @gkasprow as my supervisor for a more complex check, but I would appreciate any feedback.