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Micrel chip test...

S

server

Guest
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.



--

Father Brown\'s figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.
 
A

Anthony William Sloman

Guest
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.
Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

--
Bill Sloman, Sydney
 
M

Michael Kellett

Guest
On 05/12/2021 03:22, Anthony William Sloman wrote:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.

Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

Actually it was quite interesting.
MK
 
S

server

Guest
On Sun, 5 Dec 2021 15:56:48 +0000, Michael Kellett <mk@mkesc.co.uk>
wrote:

On 05/12/2021 03:22, Anthony William Sloman wrote:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.

Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

Actually it was quite interesting.

MK
It\'s only the chip and four connectors. All the signal traces are in
plain sight.

What bugs me is the transition from the 50 ohm traces (32 mils wide)
into and out of the 10-mil chip pins. Electromagnetic analysis
nightmare.

The good news is that a pad of an 0603 resistor is almost exactly
buried in the trace width, so has no transmission-line penalty.

I added a second trimpot instead of R77, so we can easily tweak both
the tail current (MODSET) and the equalization. EQ might affect the
minimum possible pulse width.



--

Father Brown\'s figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.
 
S

server

Guest
On Sun, 05 Dec 2021 08:27:50 -0800, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 5 Dec 2021 15:56:48 +0000, Michael Kellett <mk@mkesc.co.uk
wrote:

On 05/12/2021 03:22, Anthony William Sloman wrote:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.

Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

Actually it was quite interesting.

MK

It\'s only the chip and four connectors. All the signal traces are in
plain sight.

What bugs me is the transition from the 50 ohm traces (32 mils wide)
into and out of the 10-mil chip pins. Electromagnetic analysis
nightmare.

The good news is that a pad of an 0603 resistor is almost exactly
buried in the trace width, so has no transmission-line penalty.

I added a second trimpot instead of R77, so we can easily tweak both
the tail current (MODSET) and the equalization. EQ might affect the
minimum possible pulse width.
Equalization makes our modern world possible.



--

Father Brown\'s figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.
 
L

Lasse Langwadt Christensen

Guest
søndag den 5. december 2021 kl. 04.22.43 UTC+1 skrev bill....@ieee.org:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.
Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is..
feel free to post your own more impressive pcbs with thoroughly documented schematics to show everyone how it should be done
 
J

John S

Guest
On 12/5/2021 1:36 PM, Lasse Langwadt Christensen wrote:
søndag den 5. december 2021 kl. 04.22.43 UTC+1 skrev bill....@ieee.org:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.
Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.


feel free to post your own more impressive pcbs with thoroughly documented schematics to show everyone how it should be done
+1
 
A

Anthony William Sloman

Guest
On Monday, December 6, 2021 at 3:28:01 AM UTC+11, jla...@highlandsniptechnology.com wrote:
On Sun, 5 Dec 2021 15:56:48 +0000, Michael Kellett <m...@mkesc.co.uk
wrote:
On 05/12/2021 03:22, Anthony William Sloman wrote:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.

Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

Actually it was quite interesting.

It\'s only the chip and four connectors. All the signal traces are in
plain sight.

What bugs me is the transition from the 50 ohm traces (32 mils wide)
into and out of the 10-mil chip pins. Electromagnetic analysis
nightmare.
The Motorola/ON-Semiconductor data sheets for their ECLinPS chips included capacitance to ground for each of the inputs - I narrowed my 50R traces to 75R in the cm or so around the inputs to compensate.

I\'ve no idea whether it was a useful exercise - the layout did work, and I was able to pick up the same signal on two different inputs (which hadn\'t worked with Gigabit Logic\'s GaAs chips a few years earlier but at 800MHz rather than 200MHz - the Ga As chips weren\'t as nice as ECLinPs).

The good news is that a pad of an 0603 resistor is almost exactly
buried in the trace width, so has no transmission-line penalty.

I added a second trimpot instead of R77, so we can easily tweak both
the tail current (MODSET) and the equalization. EQ might affect the
minimum possible pulse width.
But without a circuit diagram that doesn\'t say anything all that intelligible.

--
Bill Sloman, Sydney
 
A

Anthony William Sloman

Guest
On Monday, December 6, 2021 at 6:36:58 AM UTC+11, lang...@fonz.dk wrote:
søndag den 5. december 2021 kl. 04.22.43 UTC+1 skrev bill....@ieee.org:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.
Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

feel free to post your own more impressive pcbs with thoroughly documented schematics to show everyone how it should be done.
The most recent one was in 1997, and I don\'t have immediate access to them. It got into the annual report of the Radboud (Nijmegen) University Technische Zaken - the science faculty workshop - but not in any detail.

I had to modify I pulse generator for their home built electron spin resonance spectrometer, which had was producing pulse with more jitter than they liked - less than a nanosecond but still enough to be a problem.

The original circuit had been built some ten year earlier with carefully selected TTL parts, which had to be replaced from time to time as they aged.

I bolted on an ECLinPs resynchronising section that tied the edge back to the 200 MHz master clock before spitting it out through an ECL-to-TTL converter. There must have been some jitter on the output, but the spectroscopists couldn\'t see it so they were happy.

We got the okay to do the job better with rather more ECL (and the MC100E195 delay generator - auto-recalibrated every few minutes) and I generated a lot of circuit diagrams, and the software person wrote a lot of code - but the project ran out of money before we could get to the layout stage. We\'d told them how expensive it was going to be early on, but they lost the funding they thought that they had.

--
Bill Sloman, Sydney
 
A

Anthony William Sloman

Guest
On Monday, December 6, 2021 at 11:33:21 PM UTC+11, amdx wrote:
On 12/5/2021 7:39 PM, Anthony William Sloman wrote:
On Monday, December 6, 2021 at 6:36:58 AM UTC+11, lang...@fonz.dk wrote:
søndag den 5. december 2021 kl. 04.22.43 UTC+1 skrev bill....@ieee.org:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
<snip>

The most recent one was in 1997, and I don\'t have immediate access to them. It got into the annual report of the Radboud (Nijmegen) University Technische Zaken - the science faculty workshop - but not in any detail.

I had to modify I pulse generator for their home built electron spin resonance spectrometer, which had was producing pulse with more jitter than they liked - less than a nanosecond but still enough to be a problem.

The original circuit had been built some ten year earlier with carefully selected TTL parts, which had to be replaced from time to time as they aged.

I bolted on an ECLinPs resynchronising section that tied the edge back to the 200 MHz master clock before spitting it out through an ECL-to-TTL converter. There must have been some jitter on the output, but the spectroscopists couldn\'t see it so they were happy.

We got the okay to do the job better with rather more ECL (and the MC100E195 delay generator - auto-recalibrated every few minutes) and I generated a lot of circuit diagrams, and the software person wrote a lot of code - but the project ran out of money before we could get to the layout stage. We\'d told them how expensive it was going to be early on, but they lost the funding they thought that they had.

Which one doesn\'t belong. recent, year, 1997?
\"Most recent\" is a matter of fact - there\'s no suggestion that 1997 is a recent year. Larkin seems to be trying to tell us that he is up with the start of the art, and if that is the case, the art hasn\'t changed much in the past thirty years. In reality most of the fast stuff today is buried inside fancy (and rather expensive) fast programmable logic devices which I\'ve not been able to get my claws on.

The fiddling around with microstrip lines (on the surface of a printed circuit board ) and the less dispersive buried stripline (on inner layers of a multiplayer board) goes back rather more than thirty years. It\'s a necessary part of putting stuff together, but not all that exciting.

--
Bill Sloman, Sydney
 
L

Lasse Langwadt Christensen

Guest
mandag den 6. december 2021 kl. 02.39.17 UTC+1 skrev bill....@ieee.org:
On Monday, December 6, 2021 at 6:36:58 AM UTC+11, lang...@fonz.dk wrote:
søndag den 5. december 2021 kl. 04.22.43 UTC+1 skrev bill....@ieee..org:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.
Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

feel free to post your own more impressive pcbs with thoroughly documented schematics to show everyone how it should be done.

The most recent one was in 1997, and I don\'t have immediate access to them. It got into the annual report of the Radboud (Nijmegen) University Technische Zaken - the science faculty workshop - but not in any detail.
So you have spent nearly 25 years moaning about how terrible what everyone
else is doing is compared to what fabulous things you did when you actually did something ...
 
S

server

Guest
On Mon, 6 Dec 2021 08:35:26 -0800 (PST), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

mandag den 6. december 2021 kl. 02.39.17 UTC+1 skrev bill....@ieee.org:
On Monday, December 6, 2021 at 6:36:58 AM UTC+11, lang...@fonz.dk wrote:
søndag den 5. december 2021 kl. 04.22.43 UTC+1 skrev bill....@ieee.org:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.
Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

feel free to post your own more impressive pcbs with thoroughly documented schematics to show everyone how it should be done.

The most recent one was in 1997, and I don\'t have immediate access to them. It got into the annual report of the Radboud (Nijmegen) University Technische Zaken - the science faculty workshop - but not in any detail.


So you have spent nearly 25 years moaning about how terrible what everyone
else is doing is compared to what fabulous things you did when you actually did something ...
His stories about actually designing things ages ago sound mostly like
failures.

Ignore him.



--

Father Brown\'s figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.
 
J

John S

Guest
On 12/6/2021 10:35 AM, Lasse Langwadt Christensen wrote:
mandag den 6. december 2021 kl. 02.39.17 UTC+1 skrev bill....@ieee.org:
On Monday, December 6, 2021 at 6:36:58 AM UTC+11, lang...@fonz.dk wrote:
søndag den 5. december 2021 kl. 04.22.43 UTC+1 skrev bill....@ieee.org:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.
Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

feel free to post your own more impressive pcbs with thoroughly documented schematics to show everyone how it should be done.

The most recent one was in 1997, and I don\'t have immediate access to them. It got into the annual report of the Radboud (Nijmegen) University Technische Zaken - the science faculty workshop - but not in any detail.


So you have spent nearly 25 years moaning about how terrible what everyone
else is doing is compared to what fabulous things you did when you actually did something ...
Another +1
 
A

Anthony William Sloman

Guest
On Tuesday, December 7, 2021 at 4:07:51 AM UTC+11, jla...@highlandsniptechnology.com wrote:
On Mon, 6 Dec 2021 08:35:26 -0800 (PST), Lasse Langwadt Christensen <lang...@fonz.dk> wrote:
mandag den 6. december 2021 kl. 02.39.17 UTC+1 skrev bill....@ieee.org:
On Monday, December 6, 2021 at 6:36:58 AM UTC+11, lang...@fonz.dk wrote:
søndag den 5. december 2021 kl. 04.22.43 UTC+1 skrev bill....@ieee.org:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
<snip>

> His stories about actually designing things ages ago sound mostly like failures.

John Larkin does like to think that.

> Ignore him.

John Larkin\'s ego is a fragile thing, and he prefers to imagine that his boasting is more impressive than it actually is.

--
Bill Sloman, Sydney
 
A

Anthony William Sloman

Guest
On Tuesday, December 7, 2021 at 3:35:31 AM UTC+11, lang...@fonz.dk wrote:
mandag den 6. december 2021 kl. 02.39.17 UTC+1 skrev bill....@ieee.org:
On Monday, December 6, 2021 at 6:36:58 AM UTC+11, lang...@fonz.dk wrote:
søndag den 5. december 2021 kl. 04.22.43 UTC+1 skrev bill....@ieee.org:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
<snip>

The most recent one was in 1997, and I don\'t have immediate access to them. It got into the annual report of the Radboud (Nijmegen) University Technische Zaken - the science faculty workshop - but not in any detail.

So you have spent nearly 25 years moaning about how terrible what everyone
else is doing is compared to what fabulous things you did when you actually did something ...
I don\'t complain about everybody. I complain about John Larkin boasting about stuff that wasn\'t fabulous when we did it some thirty years earlier.

It certainly isn\'t the only stuff I talk about. I do keep applying for jobs - about one a month at the moment. It is very unlikely that I will ever get one - I get maybe a nibble per year - but in the meantime I just dabble with LTSpice when something interesting shows up here (which isn\'t often).

I\'ve got a design for a tunable low distortion sine wave oscillator that I ought to turn into a working circuit, but - absent anybody who might need it - there isn\'t the motivation to push it through KiCad and get a board made.

--
Bill Sloman, Sydney
 
P

Phil Hobbs

Guest
jlarkin@highlandsniptechnology.com wrote:
On Sun, 05 Dec 2021 08:27:50 -0800, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 5 Dec 2021 15:56:48 +0000, Michael Kellett <mk@mkesc.co.uk
wrote:

On 05/12/2021 03:22, Anthony William Sloman wrote:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.

Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

Actually it was quite interesting.

MK

It\'s only the chip and four connectors. All the signal traces are in
plain sight.

What bugs me is the transition from the 50 ohm traces (32 mils wide)
into and out of the 10-mil chip pins. Electromagnetic analysis
nightmare.

The good news is that a pad of an 0603 resistor is almost exactly
buried in the trace width, so has no transmission-line penalty.

I added a second trimpot instead of R77, so we can easily tweak both
the tail current (MODSET) and the equalization. EQ might affect the
minimum possible pulse width.

Equalization makes our modern world possible.
Yup. Decision-feedback EQ in particular.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
S

server

Guest
On Tue, 7 Dec 2021 11:24:59 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Sun, 05 Dec 2021 08:27:50 -0800, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 5 Dec 2021 15:56:48 +0000, Michael Kellett <mk@mkesc.co.uk
wrote:

On 05/12/2021 03:22, Anthony William Sloman wrote:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.

Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

Actually it was quite interesting.

MK

It\'s only the chip and four connectors. All the signal traces are in
plain sight.

What bugs me is the transition from the 50 ohm traces (32 mils wide)
into and out of the 10-mil chip pins. Electromagnetic analysis
nightmare.

The good news is that a pad of an 0603 resistor is almost exactly
buried in the trace width, so has no transmission-line penalty.

I added a second trimpot instead of R77, so we can easily tweak both
the tail current (MODSET) and the equalization. EQ might affect the
minimum possible pulse width.

Equalization makes our modern world possible.

Yup. Decision-feedback EQ in particular.

Cheers

Phil Hobbs
It started with loading coils for telegraphs. Later in, long-distance
phone and radio and then TV.

https://royalsocietypublishing.org/doi/10.1098/rsta.2017.0457

I used to use a lot of cheap 88 mH toroids, left-over telephone
loading coils.

A transatlantic wire or fiber cable wouldn\'t be econonomic without
equalization. DDR rams, PCIe, JESD204, constellation modulations, all
sorts of stuff wouldn\'t be practical on FR4 without adaptive
equalization.

I wonder if any on-chip runs are equalized, or just buffered often.



--

Father Brown\'s figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.
 
P

Phil Hobbs

Guest
jlarkin@highlandsniptechnology.com wrote:
On Tue, 7 Dec 2021 11:24:59 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Sun, 05 Dec 2021 08:27:50 -0800, jlarkin@highlandsniptechnology.com
wrote:

On Sun, 5 Dec 2021 15:56:48 +0000, Michael Kellett <mk@mkesc.co.uk
wrote:

On 05/12/2021 03:22, Anthony William Sloman wrote:
On Sunday, December 5, 2021 at 4:16:24 AM UTC+11, jla...@highlandsniptechnology.com wrote:
Lately we\'re doing some small 6-layer boards with breakaway tabs for
fixturing. So there can be freebie little circuits that snap off.

We use the Micrel SY88022 laser driver in a few off-label
applications, and we don\'t know enough about it, so I hung a test
circuit on an upcoming board.

https://www.dropbox.com/s/xu559d7y81n4q6g/T502_SY88.jpg?raw=1

This chip is similar to the Maxim part that Leo Bodnar uses in his
cool fast pulsers.

Every fast SFP module must have something like this inside, and a lot
more.

Classic Larkin content-less boasting. A printed circuit layout without a schematic to provide any idea of what it is actually doing, or how.

We know that Larkin wants to impress, and we know that he doesn\'t want to do it in any way that would reveal how unimpressive the effort actually is.

Actually it was quite interesting.

MK

It\'s only the chip and four connectors. All the signal traces are in
plain sight.

What bugs me is the transition from the 50 ohm traces (32 mils wide)
into and out of the 10-mil chip pins. Electromagnetic analysis
nightmare.

The good news is that a pad of an 0603 resistor is almost exactly
buried in the trace width, so has no transmission-line penalty.

I added a second trimpot instead of R77, so we can easily tweak both
the tail current (MODSET) and the equalization. EQ might affect the
minimum possible pulse width.

Equalization makes our modern world possible.

Yup. Decision-feedback EQ in particular.

Cheers

Phil Hobbs

It started with loading coils for telegraphs. Later in, long-distance
phone and radio and then TV.

https://royalsocietypublishing.org/doi/10.1098/rsta.2017.0457

I used to use a lot of cheap 88 mH toroids, left-over telephone
loading coils.

A transatlantic wire or fiber cable wouldn\'t be econonomic without
equalization. DDR rams, PCIe, JESD204, constellation modulations, all
sorts of stuff wouldn\'t be practical on FR4 without adaptive
equalization.

I wonder if any on-chip runs are equalized, or just buffered often.
There\'s DFE done on long lines in processors.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
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