102,400 one-shots...

P

Phil Hobbs

Guest
So we\'re just finishing up a lidar detector chip in collaboration with
the chip design house (who does the actual circuitry, floor plan, and
polygon-pushing) and the airplane folks.

We did the original proof of concept using a dead-bug prototype with
pHEMTs and CFAs and sampling diodes and stuff, which was enough to get
the program going. At this point we\'re subcontractors to the camera
folks, basically helping with the design, doing the demo camera, and
coaching everybody. (We aren\'t head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of taping
out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers, unless
I\'ve miscounted. (We tried to get them to use a sane number of
monostables, such as 0, but couldn\'t make that one stick. They take up
less space than registers, we\'re told.)

The power budget is going to be entertaining. ;)

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
 
On Friday, 7 April 2023 at 19:59:52 UTC+2, Phil Hobbs wrote:
So we\'re just finishing up a lidar detector chip in collaboration with
the chip design house (who does the actual circuitry, floor plan, and
polygon-pushing) and the airplane folks.

We did the original proof of concept using a dead-bug prototype with
pHEMTs and CFAs and sampling diodes and stuff, which was enough to get
the program going. At this point we\'re subcontractors to the camera
folks, basically helping with the design, doing the demo camera, and
coaching everybody. (We aren\'t head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of taping
out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers, unless
I\'ve miscounted. (We tried to get them to use a sane number of
monostables, such as 0, but couldn\'t make that one stick. They take up
less space than registers, we\'re told.)

The power budget is going to be entertaining. ;)
Click to expand...
too late
lidar systems banned in public use world-wide
 
On Fri, 7 Apr 2023 13:59:33 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

So we\'re just finishing up a lidar detector chip in collaboration with
the chip design house (who does the actual circuitry, floor plan, and
polygon-pushing) and the airplane folks.
Click to expand...

Just between us, what did that cost?

We did the original proof of concept using a dead-bug prototype with
pHEMTs and CFAs and sampling diodes and stuff, which was enough to get
the program going. At this point we\'re subcontractors to the camera
folks, basically helping with the design, doing the demo camera, and
coaching everybody. (We aren\'t head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of taping
out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers, unless
I\'ve miscounted. (We tried to get them to use a sane number of
monostables, such as 0, but couldn\'t make that one stick. They take up
less space than registers, we\'re told.)
Click to expand...

I\'d like to do some custom mixed-signal chips. Apparently it\'s not a
totally crazy idea any more.

The power budget is going to be entertaining. ;)
Click to expand...

A mutual friend wants me to do another driver for his electro-optical
gadget. Fast driver. How does one get rid of 60 watts on maybe half a
square inch of PCB? And not block the light?

Charging and discharging capacitors, in principle, takes no power.

Cheers

Phil Hobbs
Click to expand...
 
On Fri, 7 Apr 2023 11:21:40 -0700 (PDT), a a <manta103g@gmail.com>
wrote:

On Friday, 7 April 2023 at 19:59:52 UTC+2, Phil Hobbs wrote:
So we\'re just finishing up a lidar detector chip in collaboration with
the chip design house (who does the actual circuitry, floor plan, and
polygon-pushing) and the airplane folks.

We did the original proof of concept using a dead-bug prototype with
pHEMTs and CFAs and sampling diodes and stuff, which was enough to get
the program going. At this point we\'re subcontractors to the camera
folks, basically helping with the design, doing the demo camera, and
coaching everybody. (We aren\'t head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of taping
out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers, unless
I\'ve miscounted. (We tried to get them to use a sane number of
monostables, such as 0, but couldn\'t make that one stick. They take up
less space than registers, we\'re told.)

The power budget is going to be entertaining. ;)

too late
lidar systems banned in public use world-wide
Click to expand...

San Francisco is crawling with driverless cars that are decorated with
spinning gadgets.

google waymo lidar

Somebody showed us a single-chip lidar rangefinder that works at a few
inches and costs a couple of dollars. Can\'t remember who.
 
On Friday, April 7, 2023 at 1:23:39 PM UTC-7, John Larkin wrote:
On Fri, 7 Apr 2023 13:59:33 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

So we\'re just finishing up a lidar detector chip in collaboration with
the chip design house (who does the actual circuitry, floor plan, and
polygon-pushing) and the airplane folks.
....
It contains 102,400 one-shots and 106,496 Class A amplifiers, unless
I\'ve miscounted. (We tried to get them to use a sane number of
monostables, such as 0, but couldn\'t make that one stick. They take up
less space than registers, we\'re told.)
Click to expand...

So, it\'s similar to a dynamic RAM versus static RAM storage?

...How does one get rid of 60 watts on maybe half a
square inch of PCB? And not block the light?

Charging and discharging capacitors, in principle, takes no power.
Click to expand...

If you charge \'em with a switch to +V, and discharge \'em with a switch to GND,
it certainly DOES take power. Switches aren\'t zero-impedance, so it warms them
(and/or the capacitors aren\'t zero-ESR, and it warms them instead).
 
Am 07.04.23 um 22:23 schrieb John Larkin:

I\'d like to do some custom mixed-signal chips. Apparently it\'s not a
totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his electro-optical
gadget. Fast driver. How does one get rid of 60 watts on maybe half a
square inch of PCB? And not block the light?
Click to expand...

Our wafer testers got rid of 50000 Watts for 4K test pins
in less than a cubic meter, and it went this way:
\"My uncle works at DaimlerBenz/Mercedes here in Böblingen,
I\'ll ask him\" and he made it work. Masses of nekkid square
centimeter chips, Alu block, copper tubes, cold water...

:) Gerhard
 
On Friday, April 7, 2023 at 4:23:39 PM UTC-4, John Larkin wrote:
On Fri, 7 Apr 2023 13:59:33 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

So we\'re just finishing up a lidar detector chip in collaboration with
the chip design house (who does the actual circuitry, floor plan, and
polygon-pushing) and the airplane folks.
Just between us, what did that cost?

We did the original proof of concept using a dead-bug prototype with
pHEMTs and CFAs and sampling diodes and stuff, which was enough to get
the program going. At this point we\'re subcontractors to the camera
folks, basically helping with the design, doing the demo camera, and
coaching everybody. (We aren\'t head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of taping
out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers, unless
I\'ve miscounted. (We tried to get them to use a sane number of
monostables, such as 0, but couldn\'t make that one stick. They take up
less space than registers, we\'re told.)
I\'d like to do some custom mixed-signal chips. Apparently it\'s not a
totally crazy idea any more.

The power budget is going to be entertaining. ;)
A mutual friend wants me to do another driver for his electro-optical
gadget. Fast driver. How does one get rid of 60 watts on maybe half a
square inch of PCB? And not block the light?

Charging and discharging capacitors, in principle, takes no power.
Click to expand...

If that were true, CMOS devices could be built that would operate at MHz, but draw no dynamic power. CMOS power dissipation is purely in the charge being shuttled when toggling the signal levels. I\'ve never heard of any way around it, other than not changing signal levels.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
 
On Fri, 7 Apr 2023 23:23:39 +0200, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:

Am 07.04.23 um 22:23 schrieb John Larkin:

I\'d like to do some custom mixed-signal chips. Apparently it\'s not a
totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his electro-optical
gadget. Fast driver. How does one get rid of 60 watts on maybe half a
square inch of PCB? And not block the light?

Our wafer testers got rid of 50000 Watts for 4K test pins
in less than a cubic meter, and it went this way:
\"My uncle works at DaimlerBenz/Mercedes here in Böblingen,
I\'ll ask him\" and he made it work. Masses of nekkid square
centimeter chips, Alu block, copper tubes, cold water...

:) Gerhard
Click to expand...

There are some \"pin driver\" chips used in test systems, but as far as
I can tell they are not sold to civilians.
 
On 2023-04-07 16:23, John Larkin wrote:
On Fri, 7 Apr 2023 13:59:33 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

So we\'re just finishing up a lidar detector chip in collaboration
with the chip design house (who does the actual circuitry, floor
plan, and polygon-pushing) and the airplane folks.

Just between us, what did that cost?
Click to expand...

It was surprisingly reasonable--even a dedicated engineering run (20ish
wafers) was about $50k, I think, and the multiproject wafer approach (a
la MOSIS) is considerably cheaper than that. This was on an XFAB 180 nm
process with APDs and SPADs.

We\'ve been kicking around doing the guts of a laser noise canceller on a
transistor array chip--onsemi will do that for just a few $k.

We did the original proof of concept using a dead-bug prototype
with pHEMTs and CFAs and sampling diodes and stuff, which was
enough to get the program going. At this point we\'re
subcontractors to the camera folks, basically helping with the
design, doing the demo camera, and coaching everybody. (We aren\'t
head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of
taping out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers,
unless I\'ve miscounted. (We tried to get them to use a sane number
of monostables, such as 0, but couldn\'t make that one stick. They
take up less space than registers, we\'re told.)

I\'d like to do some custom mixed-signal chips. Apparently it\'s not a
totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his electro-optical
gadget. Fast driver. How does one get rid of 60 watts on maybe half a
square inch of PCB? And not block the light?
Click to expand...

A loop of copper tube with water running through it, or maybe a vapor
chamber heat spreader with a finned heat sink someplace nearby. Vapor
chambers are about 10x better than copper, iirc. Digikey sells them.

> Charging and discharging capacitors, in principle, takes no power.

The canonical method for charging and discharging caps fast and
efficiently is to use an inductor and diode to force the charge waveform
to be half a cycle of a sine wave. That\'s how a lot of lidar laser
drivers work.

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
 
On 2023-04-07 17:52, Ricky wrote:
On Friday, April 7, 2023 at 4:23:39 PM UTC-4, John Larkin wrote:
On Fri, 7 Apr 2023 13:59:33 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

So we\'re just finishing up a lidar detector chip in collaboration
with the chip design house (who does the actual circuitry, floor
plan, and polygon-pushing) and the airplane folks.
Just between us, what did that cost?

We did the original proof of concept using a dead-bug prototype
with pHEMTs and CFAs and sampling diodes and stuff, which was
enough to get the program going. At this point we\'re
subcontractors to the camera folks, basically helping with the
design, doing the demo camera, and coaching everybody. (We aren\'t
head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of
taping out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers,
unless I\'ve miscounted. (We tried to get them to use a sane
number of monostables, such as 0, but couldn\'t make that one
stick. They take up less space than registers, we\'re told.)
I\'d like to do some custom mixed-signal chips. Apparently it\'s not
a totally crazy idea any more.

The power budget is going to be entertaining. ;)
A mutual friend wants me to do another driver for his
electro-optical gadget. Fast driver. How does one get rid of 60
watts on maybe half a square inch of PCB? And not block the light?

Charging and discharging capacitors, in principle, takes no power.

If that were true, CMOS devices could be built that would operate at
MHz, but draw no dynamic power. CMOS power dissipation is purely in
the charge being shuttled when toggling the signal levels. I\'ve
never heard of any way around it, other than not changing signal
levels.
Click to expand...

The inductor + diode trick does it.

It\'s tough to get big enough on-chip inductors to do it with logic, of
course, but maybe not absolutely impossible--kinetic inductance in small
superconducting circuits can be startlingly large.

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
 
On Fri, 7 Apr 2023 19:59:07 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2023-04-07 17:52, Ricky wrote:
On Friday, April 7, 2023 at 4:23:39?PM UTC-4, John Larkin wrote:
On Fri, 7 Apr 2023 13:59:33 -0400, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

So we\'re just finishing up a lidar detector chip in collaboration
with the chip design house (who does the actual circuitry, floor
plan, and polygon-pushing) and the airplane folks.
Just between us, what did that cost?

We did the original proof of concept using a dead-bug prototype
with pHEMTs and CFAs and sampling diodes and stuff, which was
enough to get the program going. At this point we\'re
subcontractors to the camera folks, basically helping with the
design, doing the demo camera, and coaching everybody. (We aren\'t
head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of
taping out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers,
unless I\'ve miscounted. (We tried to get them to use a sane
number of monostables, such as 0, but couldn\'t make that one
stick. They take up less space than registers, we\'re told.)
I\'d like to do some custom mixed-signal chips. Apparently it\'s not
a totally crazy idea any more.

The power budget is going to be entertaining. ;)
A mutual friend wants me to do another driver for his
electro-optical gadget. Fast driver. How does one get rid of 60
watts on maybe half a square inch of PCB? And not block the light?

Charging and discharging capacitors, in principle, takes no power.

If that were true, CMOS devices could be built that would operate at
MHz, but draw no dynamic power. CMOS power dissipation is purely in
the charge being shuttled when toggling the signal levels. I\'ve
never heard of any way around it, other than not changing signal
levels.


The inductor + diode trick does it.
Click to expand...

My Pockels Cell driver charges the capacitive load in a few
nanoseconds, and then recovers the energy in a few more. That\'s why it
is so small and runs off a wall wart.

http://www.highlandtechnology.com/DSS/T850DS.shtml

It does use an inductor, so the architecture would probably be hard to
replicate in an IC.
 
On Fri, 7 Apr 2023 19:24:52 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2023-04-07 16:23, John Larkin wrote:
On Fri, 7 Apr 2023 13:59:33 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

So we\'re just finishing up a lidar detector chip in collaboration
with the chip design house (who does the actual circuitry, floor
plan, and polygon-pushing) and the airplane folks.

Just between us, what did that cost?

It was surprisingly reasonable--even a dedicated engineering run (20ish
wafers) was about $50k, I think, and the multiproject wafer approach (a
la MOSIS) is considerably cheaper than that. This was on an XFAB 180 nm
process with APDs and SPADs.

We\'ve been kicking around doing the guts of a laser noise canceller on a
transistor array chip--onsemi will do that for just a few $k.

We did the original proof of concept using a dead-bug prototype
with pHEMTs and CFAs and sampling diodes and stuff, which was
enough to get the program going. At this point we\'re
subcontractors to the camera folks, basically helping with the
design, doing the demo camera, and coaching everybody. (We aren\'t
head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of
taping out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers,
unless I\'ve miscounted. (We tried to get them to use a sane number
of monostables, such as 0, but couldn\'t make that one stick. They
take up less space than registers, we\'re told.)

I\'d like to do some custom mixed-signal chips. Apparently it\'s not a
totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his electro-optical
gadget. Fast driver. How does one get rid of 60 watts on maybe half a
square inch of PCB? And not block the light?

A loop of copper tube with water running through it, or maybe a vapor
chamber heat spreader with a finned heat sink someplace nearby. Vapor
chambers are about 10x better than copper, iirc. Digikey sells them.

Charging and discharging capacitors, in principle, takes no power.

The canonical method for charging and discharging caps fast and
efficiently is to use an inductor and diode to force the charge waveform
to be half a cycle of a sine wave. That\'s how a lot of lidar laser
drivers work.

Cheers

Phil Hobbs
Click to expand...

In theory, one can run up a parallel LC circuit and, once pumped, get
a zillion cap charge and discharge cycles for free after that.

Then, at any zero crossing, short it out for as long as you like, and
turn it loose any time after that to resume the oscillation.

Nice example of a differential equation with initial conditions.
 
On 2023-04-07 17:23, Gerhard Hoffmann wrote:
Am 07.04.23 um 22:23 schrieb John Larkin:

I\'d like to do some custom mixed-signal chips. Apparently it\'s not
a totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his
electro-optical gadget. Fast driver. How does one get rid of 60
watts on maybe half a square inch of PCB? And not block the light?

Our wafer testers got rid of 50000 Watts for 4K test pins in less
than a cubic meter, and it went this way: \"My uncle works at
DaimlerBenz/Mercedes here in Böblingen,
Click to expand...

As an aside, when I was at IBM we had a research group there, which
among non-German speakers was usually called \"Bubblegum.\" ;)

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
 
On 2023-04-07 21:08, John Larkin wrote:
On Fri, 7 Apr 2023 19:24:52 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2023-04-07 16:23, John Larkin wrote:
On Fri, 7 Apr 2023 13:59:33 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

So we\'re just finishing up a lidar detector chip in collaboration
with the chip design house (who does the actual circuitry, floor
plan, and polygon-pushing) and the airplane folks.

Just between us, what did that cost?

It was surprisingly reasonable--even a dedicated engineering run (20ish
wafers) was about $50k, I think, and the multiproject wafer approach (a
la MOSIS) is considerably cheaper than that. This was on an XFAB 180 nm
process with APDs and SPADs.

We\'ve been kicking around doing the guts of a laser noise canceller on a
transistor array chip--onsemi will do that for just a few $k.

We did the original proof of concept using a dead-bug prototype
with pHEMTs and CFAs and sampling diodes and stuff, which was
enough to get the program going. At this point we\'re
subcontractors to the camera folks, basically helping with the
design, doing the demo camera, and coaching everybody. (We aren\'t
head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of
taping out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers,
unless I\'ve miscounted. (We tried to get them to use a sane number
of monostables, such as 0, but couldn\'t make that one stick. They
take up less space than registers, we\'re told.)

I\'d like to do some custom mixed-signal chips. Apparently it\'s not a
totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his electro-optical
gadget. Fast driver. How does one get rid of 60 watts on maybe half a
square inch of PCB? And not block the light?

A loop of copper tube with water running through it, or maybe a vapor
chamber heat spreader with a finned heat sink someplace nearby. Vapor
chambers are about 10x better than copper, iirc. Digikey sells them.

Charging and discharging capacitors, in principle, takes no power.

The canonical method for charging and discharging caps fast and
efficiently is to use an inductor and diode to force the charge waveform
to be half a cycle of a sine wave. That\'s how a lot of lidar laser
drivers work.

Cheers

Phil Hobbs

In theory, one can run up a parallel LC circuit and, once pumped, get
a zillion cap charge and discharge cycles for free after that.

Then, at any zero crossing, short it out for as long as you like, and
turn it loose any time after that to resume the oscillation.

Nice example of a differential equation with initial conditions.
Click to expand...

That\'s basically the dual of the inductor + diode thing, which switches
automatically at the voltage peak.

+20V
0--LLLL-->|--*---------* 40V peak
| |
| LD Triple-stack Osram laser
few nF CCC |
CCC 0
| \\ EPC GaN FET
| 0
| |
GND GND

The Uber one I took apart a few years ago had a total inductance (around
that cap - laser - switch loop) of just under 400 pH, about half in the
source and half in the drain. (Ascertained by dorking LTspice till the
waveforms agreed with my data.)

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
 
On 2023-04-08 07:52, Phil Hobbs wrote:
On 2023-04-07 21:08, John Larkin wrote:
On Fri, 7 Apr 2023 19:24:52 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2023-04-07 16:23, John Larkin wrote:
On Fri, 7 Apr 2023 13:59:33 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

So we\'re just finishing up a lidar detector chip in collaboration
with the chip design house (who does the actual circuitry, floor
plan, and polygon-pushing) and the airplane folks.

Just between us, what did that cost?

It was surprisingly reasonable--even a dedicated engineering run (20ish
wafers) was about $50k, I think, and the multiproject wafer approach (a
la MOSIS) is considerably cheaper than that.  This was on an XFAB 180 nm
process with APDs and SPADs.

We\'ve been kicking around doing the guts of a laser noise canceller on a
transistor array chip--onsemi will do that for just a few $k.

We did the original proof of concept using a dead-bug prototype
with pHEMTs and CFAs and sampling diodes and stuff, which was
enough to get the program going.  At this point we\'re
subcontractors to the camera folks, basically helping with the
design, doing the demo camera, and coaching everybody.  (We aren\'t
head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of
taping out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers,
unless I\'ve miscounted. (We tried to get them to use a sane number
of monostables, such as 0, but couldn\'t make that one stick.  They
take up less space than registers, we\'re told.)

I\'d like to do some custom mixed-signal chips. Apparently it\'s not a
  totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his electro-optical
gadget. Fast driver. How does one get rid of 60 watts on maybe half a
square inch of PCB? And not block the light?

A loop of copper tube with water running through it, or maybe a vapor
chamber heat spreader with a finned heat sink someplace nearby.  Vapor
chambers are about 10x better than copper, iirc.  Digikey sells them.

Charging and discharging capacitors, in principle, takes no power.

The canonical method for charging and discharging caps fast and
efficiently is to use an inductor and diode to force the charge waveform
to be half a cycle of a sine wave.  That\'s how a lot of lidar laser
drivers work.

Cheers

Phil Hobbs

In theory, one can run up a parallel LC circuit and, once pumped, get
a zillion cap charge and discharge cycles for free after that.

Then, at any zero crossing, short it out for as long as you like, and
turn it loose any time after that to resume the oscillation.

Nice example of a differential equation with initial conditions.


That\'s basically the dual of the inductor + diode thing, which switches
automatically at the voltage peak.

+20V
   0--LLLL-->|--*---------*  40V peak
                |         |
                |         LD   Triple-stack Osram laser
       few nF  CCC        |
               CCC        0
                |          \\  EPC GaN FET
                |         0
                |         |
               GND       GND

The Uber one I took apart a few years ago had a total inductance (around
that cap - laser - switch loop) of just under 400 pH, about half in the
source and half in the drain.  (Ascertained by dorking LTspice till the
waveforms agreed with my data.)
Click to expand...

I should add that Uber wasn\'t using the inductor trick--they had a 40V
power supply and a resistor. Demonstrating that they weren\'t the same
circuit was the point of the exercise.

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
 
Am 08.04.23 um 13:38 schrieb Phil Hobbs:
On 2023-04-07 17:23, Gerhard Hoffmann wrote:
Am 07.04.23 um 22:23 schrieb John Larkin:

I\'d like to do some custom mixed-signal chips. Apparently it\'s not
a totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his
electro-optical gadget. Fast driver. How does one get rid of 60
watts on maybe half a square inch of PCB? And not block the light?

Our wafer testers got rid of 50000 Watts for 4K test pins in less
than a cubic meter, and it went this way: \"My uncle works at
DaimlerBenz/Mercedes here in Böblingen,

As an aside, when I was at IBM we had a research group there, which
among non-German speakers was usually called \"Bubblegum.\" ;)
Click to expand...

Böblingen was the old HP campus, the wafertester was the Verigy
V93K, ex HP. I had one reserved for me for 4 days a week.
The tester chips had an onchip Mips 4000, a CPU I do like very
much.
There was an engineering hall with 300 engineers,
285 of which were software people. Even me, I integrated TDRs
into a 10 Meg lines software system. Don\'t try to explain what
a TDR does to a pure software guy.

A textbook example of how you can turn one of the world\'s best
technology companies into a pile of debris ready to be eaten by
other companies.

The IBM campus is 5-10 Km more south; a friend of mine was developing
caches for IBM mainframes there.

Cheers, Gerhard
 
On Friday, April 7, 2023 at 1:59:52 PM UTC-4, Phil Hobbs wrote:
So we\'re just finishing up a lidar detector chip in collaboration with
the chip design house (who does the actual circuitry, floor plan, and
polygon-pushing) and the airplane folks.

We did the original proof of concept using a dead-bug prototype with
pHEMTs and CFAs and sampling diodes and stuff, which was enough to get
the program going. At this point we\'re subcontractors to the camera
folks, basically helping with the design, doing the demo camera, and
coaching everybody. (We aren\'t head coach--maybe offensive coordinator.) ;)

It\'s been going for a couple of years, and we\'re at the point of taping
out the first of the second-generation chips.

It contains 102,400 one-shots and 106,496 Class A amplifiers, unless
I\'ve miscounted. (We tried to get them to use a sane number of
monostables, such as 0, but couldn\'t make that one stick. They take up
less space than registers, we\'re told.)
Click to expand...

They\'re probably right. If you need a small duration pulse, like a trigger, then an on-chip monostable is very space conservative:

https://www.worldscientific.com/doi/pdf/10.1142/S0218126619200019

.... exhaustive of all the possible features, but the core function appears quite economical.

What\'s a Class A amplifier? A simple N-MOS with a MOS current source load. Again, not exactly a space hog.

The power budget is going to be entertaining. ;)

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
Click to expand...
 
On Sat, 8 Apr 2023 07:38:39 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2023-04-07 17:23, Gerhard Hoffmann wrote:
Am 07.04.23 um 22:23 schrieb John Larkin:

I\'d like to do some custom mixed-signal chips. Apparently it\'s not
a totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his
electro-optical gadget. Fast driver. How does one get rid of 60
watts on maybe half a square inch of PCB? And not block the light?

Our wafer testers got rid of 50000 Watts for 4K test pins in less
than a cubic meter, and it went this way: \"My uncle works at
DaimlerBenz/Mercedes here in Böblingen,

As an aside, when I was at IBM we had a research group there, which
among non-German speakers was usually called \"Bubblegum.\" ;)

Cheers

Phil Hobbs
Click to expand...

What do Germans call bubblegum? I\'d expect a very long word.
 
On Sat, 8 Apr 2023 14:47:29 +0200, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:

Am 08.04.23 um 13:38 schrieb Phil Hobbs:
On 2023-04-07 17:23, Gerhard Hoffmann wrote:
Am 07.04.23 um 22:23 schrieb John Larkin:

I\'d like to do some custom mixed-signal chips. Apparently it\'s not
a totally crazy idea any more.


The power budget is going to be entertaining. ;)

A mutual friend wants me to do another driver for his
electro-optical gadget. Fast driver. How does one get rid of 60
watts on maybe half a square inch of PCB? And not block the light?

Our wafer testers got rid of 50000 Watts for 4K test pins in less
than a cubic meter, and it went this way: \"My uncle works at
DaimlerBenz/Mercedes here in Böblingen,

As an aside, when I was at IBM we had a research group there, which
among non-German speakers was usually called \"Bubblegum.\" ;)

Böblingen was the old HP campus, the wafertester was the Verigy
V93K, ex HP. I had one reserved for me for 4 days a week.
The tester chips had an onchip Mips 4000, a CPU I do like very
much.
There was an engineering hall with 300 engineers,
285 of which were software people. Even me, I integrated TDRs
into a 10 Meg lines software system. Don\'t try to explain what
a TDR does to a pure software guy.

A textbook example of how you can turn one of the world\'s best
technology companies into a pile of debris ready to be eaten by
other companies.

The IBM campus is 5-10 Km more south; a friend of mine was developing
caches for IBM mainframes there.

Cheers, Gerhard
Click to expand...

I have two wonderful books.

The HP Way by David Packard 1995

and

The Journey by Carla Fiorina 2000

Everybody should read them. The second one will only take a few
minutes.
 
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