Lambda diode gyrator, pt 2

B

bitrex

Guest
With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

<https://imgur.com/a/NZM9lBl>

While preserving the low-frequency response
 
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response
Click to expand...

Why not a capacitor and a resistor as a highpass? That will go to GHz.




--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
On 7/9/19 2:30 PM, bitrex wrote:
On 7/9/19 2:18 PM, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one

I never understood the appeal of gyrators. One opamp, or one LC, makes
a second-order section.

Maybe they have some advantages for on-chip analog filters. JT used to
like them.



They were probably more attractive at a certain time when cost of op-amp
sections had fallen to make them almost-jellybeans but precision
components were not and there were advantages wrt component tolerance
variation. 0.1% resistors and caps aren't going to break the bank nowadays.

They're useful for simulating very large inductances IIRC there was a JT
patent for a FSK modem that used a gyrator as the inductance in a
parallel RL to make a narrowband filter for some laughably low frequency
by today's standards like 25kHz or something.
Click to expand...

parallel LC, rather
 
On 7/9/19 2:18 PM, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one

I never understood the appeal of gyrators. One opamp, or one LC, makes
a second-order section.

Maybe they have some advantages for on-chip analog filters. JT used to
like them.
Click to expand...

They were probably more attractive at a certain time when cost of op-amp
sections had fallen to make them almost-jellybeans but precision
components were not and there were advantages wrt component tolerance
variation. 0.1% resistors and caps aren't going to break the bank nowadays.

They're useful for simulating very large inductances IIRC there was a JT
patent for a FSK modem that used a gyrator as the inductance in a
parallel RL to make a narrowband filter for some laughably low frequency
by today's standards like 25kHz or something.
 
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one
Click to expand...

I never understood the appeal of gyrators. One opamp, or one LC, makes
a second-order section.

Maybe they have some advantages for on-chip analog filters. JT used to
like them.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.
Click to expand...

The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one
 
On 7/9/19 2:18 PM, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.




The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one

I never understood the appeal of gyrators. One opamp, or one LC, makes
a second-order section.

Maybe they have some advantages for on-chip analog filters. JT used to
like them.
Click to expand...

There used to be a Bob Pease video on YT where he designed a floating
inductance gyrator of very large value like 1H or something, someone
posted it here at one point, idk if anyone agreed with my belief at the
time that a floating 1H equivalent inductance gyrator that's limited to
tens of uA of output current is IMO a fucking useless device it's a
resistor made with like 12 parts
 
On 7/9/19 8:27 PM, George Herold wrote:
On Tuesday, July 9, 2019 at 2:23:15 PM UTC-4, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one


Well for me it was that can get good caps, (and inductors, are more
complicated.)

I like the state variable filter... and better opamps, make it better.
(mostly 100k Hz and below.)

Speaking of caps. Is there a good, (good means mostly
low dissipation factor, though size/ price also matters.)
1 uF cap? At 0.1 uF I'm using cog ceramics.
Maybe I should just stack up 0.1uF ceramics and add some
more R?
(I'm using some polystyrene automotive ones from DK
in the current design, but DF is not great.)

George H.
Click to expand...

Which are the ones you're using now, specifically? 1uF polystyrene caps
sounds pricey and large!

The PCB mount plastic caps I've used in that range before are these
metalized polyester EVOX/KEMET units:

<https://www.mouser.com/datasheet/2/212/F3294_MMK-1101858.pdf>

about $1 in singles, 50 cent in hundreds for the 63VDC type. the loss
tangent is rated at <= 0.005 @ 1kHz.
 
On Tuesday, July 9, 2019 at 2:23:15 PM UTC-4, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one
Click to expand...

Well for me it was that can get good caps, (and inductors, are more
complicated.)

I like the state variable filter... and better opamps, make it better.
(mostly 100k Hz and below.)

Speaking of caps. Is there a good, (good means mostly
low dissipation factor, though size/ price also matters.)
1 uF cap? At 0.1 uF I'm using cog ceramics.
Maybe I should just stack up 0.1uF ceramics and add some
more R?
(I'm using some polystyrene automotive ones from DK
in the current design, but DF is not great.)

George H.


I never understood the appeal of gyrators. One opamp, or one LC, makes
a second-order section.

Maybe they have some advantages for on-chip analog filters. JT used to
like them.



--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Click to expand...
 
On 7/9/19 2:18 PM, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one

I never understood the appeal of gyrators. One opamp, or one LC, makes
a second-order section.

Maybe they have some advantages for on-chip analog filters. JT used to
like them.
Click to expand...

The main benefit of op amp gyrators is low component sensitivity--it's
0.5, just like a passive LC. I've never used a built-up one either.

On the other hand, a cap multiplier is also a gyrator. ;)

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 Wed, 10 Jul 2019 10:23:57 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 7/9/19 2:18 PM, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one

I never understood the appeal of gyrators. One opamp, or one LC, makes
a second-order section.

Maybe they have some advantages for on-chip analog filters. JT used to
like them.



The main benefit of op amp gyrators is low component sensitivity--it's
0.5, just like a passive LC. I've never used a built-up one either.

On the other hand, a cap multiplier is also a gyrator. ;)

Cheers

Phil Hobbs
Click to expand...

I designed the Winch Control Intercommunications Subsystem for the
C5A. Part of it was a very c-multiplier-like circuit to filter the DC
supply for the audio parts. There is a clever RC circuit that has a
gain of over 1, and I discovered it by accident; my c-multiplier
oscillated.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
On Tuesday, July 9, 2019 at 8:44:07 PM UTC-4, bitrex wrote:
On 7/9/19 8:27 PM, George Herold wrote:
On Tuesday, July 9, 2019 at 2:23:15 PM UTC-4, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one


Well for me it was that can get good caps, (and inductors, are more
complicated.)

I like the state variable filter... and better opamps, make it better.
(mostly 100k Hz and below.)

Speaking of caps. Is there a good, (good means mostly
low dissipation factor, though size/ price also matters.)
1 uF cap? At 0.1 uF I'm using cog ceramics.
Maybe I should just stack up 0.1uF ceramics and add some
more R?
(I'm using some polystyrene automotive ones from DK
in the current design, but DF is not great.)

George H.

Which are the ones you're using now, specifically? 1uF polystyrene caps
sounds pricey and large!

The PCB mount plastic caps I've used in that range before are these
metalized polyester EVOX/KEMET units:

https://www.mouser.com/datasheet/2/212/F3294_MMK-1101858.pdf

about $1 in singles, 50 cent in hundreds for the 63VDC type. the loss
tangent is rated at <= 0.005 @ 1kHz.
Click to expand...

Sorry, they are PET not polystyrene... my mistake.
https://www.digikey.com/products/en?keywords=495-1119-nd

GH
 
On 7/10/19 11:00 AM, George Herold wrote:
On Tuesday, July 9, 2019 at 8:44:07 PM UTC-4, bitrex wrote:
On 7/9/19 8:27 PM, George Herold wrote:
On Tuesday, July 9, 2019 at 2:23:15 PM UTC-4, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one


Well for me it was that can get good caps, (and inductors, are more
complicated.)

I like the state variable filter... and better opamps, make it better.
(mostly 100k Hz and below.)

Speaking of caps. Is there a good, (good means mostly
low dissipation factor, though size/ price also matters.)
1 uF cap? At 0.1 uF I'm using cog ceramics.
Maybe I should just stack up 0.1uF ceramics and add some
more R?
(I'm using some polystyrene automotive ones from DK
in the current design, but DF is not great.)

George H.

Which are the ones you're using now, specifically? 1uF polystyrene caps
sounds pricey and large!

The PCB mount plastic caps I've used in that range before are these
metalized polyester EVOX/KEMET units:

https://www.mouser.com/datasheet/2/212/F3294_MMK-1101858.pdf

about $1 in singles, 50 cent in hundreds for the 63VDC type. the loss
tangent is rated at <= 0.005 @ 1kHz.

Sorry, they are PET not polystyrene... my mistake.
https://www.digikey.com/products/en?keywords=495-1119-nd

GH
Click to expand...

That makes sense. Raw polystyrene is an almost ideal dielectric except
that the Dk is low and can't be made that thin. I have some 0.22uF
polystyrene caps and they're really big and probably cost a lot (can't
remember what I paid for 'em exactly, though.)
 
On 7/10/19 11:00 AM, George Herold wrote:
On Tuesday, July 9, 2019 at 8:44:07 PM UTC-4, bitrex wrote:
On 7/9/19 8:27 PM, George Herold wrote:
On Tuesday, July 9, 2019 at 2:23:15 PM UTC-4, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one


Well for me it was that can get good caps, (and inductors, are more
complicated.)

I like the state variable filter... and better opamps, make it better.
(mostly 100k Hz and below.)

Speaking of caps. Is there a good, (good means mostly
low dissipation factor, though size/ price also matters.)
1 uF cap? At 0.1 uF I'm using cog ceramics.
Maybe I should just stack up 0.1uF ceramics and add some
more R?
(I'm using some polystyrene automotive ones from DK
in the current design, but DF is not great.)

George H.

Which are the ones you're using now, specifically? 1uF polystyrene caps
sounds pricey and large!

The PCB mount plastic caps I've used in that range before are these
metalized polyester EVOX/KEMET units:

https://www.mouser.com/datasheet/2/212/F3294_MMK-1101858.pdf

about $1 in singles, 50 cent in hundreds for the 63VDC type. the loss
tangent is rated at <= 0.005 @ 1kHz.

Sorry, they are PET not polystyrene... my mistake.
https://www.digikey.com/products/en?keywords=495-1119-nd

GH
Click to expand...

Polypropylene is generally OK. IIRC Win has some stuff on dielectrics
in AoE3. Polystyrene caps went away because it melts at 100C, which
makes reflow soldering sort of hard unless you're using Wood's metal or
something.

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 Wednesday, July 10, 2019 at 12:37:13 PM UTC-4, Phil Hobbs wrote:
On 7/10/19 11:00 AM, George Herold wrote:
On Tuesday, July 9, 2019 at 8:44:07 PM UTC-4, bitrex wrote:
On 7/9/19 8:27 PM, George Herold wrote:
On Tuesday, July 9, 2019 at 2:23:15 PM UTC-4, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one


Well for me it was that can get good caps, (and inductors, are more
complicated.)

I like the state variable filter... and better opamps, make it better.
(mostly 100k Hz and below.)

Speaking of caps. Is there a good, (good means mostly
low dissipation factor, though size/ price also matters.)
1 uF cap? At 0.1 uF I'm using cog ceramics.
Maybe I should just stack up 0.1uF ceramics and add some
more R?
(I'm using some polystyrene automotive ones from DK
in the current design, but DF is not great.)

George H.

Which are the ones you're using now, specifically? 1uF polystyrene caps
sounds pricey and large!

The PCB mount plastic caps I've used in that range before are these
metalized polyester EVOX/KEMET units:

https://www.mouser.com/datasheet/2/212/F3294_MMK-1101858.pdf

about $1 in singles, 50 cent in hundreds for the 63VDC type. the loss
tangent is rated at <= 0.005 @ 1kHz.

Sorry, they are PET not polystyrene... my mistake.
https://www.digikey.com/products/en?keywords=495-1119-nd

GH


Polypropylene is generally OK. IIRC Win has some stuff on dielectrics
in AoE3. Polystyrene caps went away because it melts at 100C, which
makes reflow soldering sort of hard unless you're using Wood's metal or
something.
Click to expand...
Yeah we use to buy more polypropylene caps. But now all the lower voltage
ones seem to have gone away, so you are stuck with higher voltage (bigger)
ones. I use more COG ceramics.. but they top out at ~ 0.1 uF.
(just went searching DK again for large value cog ceramics)

George H.
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 10/07/2019 6:15 pm, George Herold wrote:
On Wednesday, July 10, 2019 at 12:37:13 PM UTC-4, Phil Hobbs wrote:
On 7/10/19 11:00 AM, George Herold wrote:
On Tuesday, July 9, 2019 at 8:44:07 PM UTC-4, bitrex wrote:
On 7/9/19 8:27 PM, George Herold wrote:
On Tuesday, July 9, 2019 at 2:23:15 PM UTC-4, John Larkin wrote:
On Tue, 9 Jul 2019 14:14:06 -0400, bitrex <user@example.net> wrote:

On 7/9/19 12:04 PM, John Larkin wrote:
On Tue, 9 Jul 2019 12:02:02 -0400, bitrex <user@example.net> wrote:

With a more appropriate op amp and better choice of operating
point for the diode it looks like the lambda diode load really does
provide a significant bandwidth improvement as compared to a resistive
load for the gyrator in the high-pass configuration, about 4x, here:

https://imgur.com/a/NZM9lBl

While preserving the low-frequency response

Why not a capacitor and a resistor as a highpass? That will go to GHz.





The "L"-R highpass is the simplest example I could think of for
experimenting with using the LD this way.

I can't of a great real-world use case for a LR gyrator high-pass
structure off the top of my head, maybe someone knows of one


Well for me it was that can get good caps, (and inductors, are more
complicated.)

I like the state variable filter... and better opamps, make it better.
(mostly 100k Hz and below.)

Speaking of caps. Is there a good, (good means mostly
low dissipation factor, though size/ price also matters.)
1 uF cap? At 0.1 uF I'm using cog ceramics.
Maybe I should just stack up 0.1uF ceramics and add some
more R?
(I'm using some polystyrene automotive ones from DK
in the current design, but DF is not great.)

George H.

Which are the ones you're using now, specifically? 1uF polystyrene caps
sounds pricey and large!

The PCB mount plastic caps I've used in that range before are these
metalized polyester EVOX/KEMET units:

https://www.mouser.com/datasheet/2/212/F3294_MMK-1101858.pdf

about $1 in singles, 50 cent in hundreds for the 63VDC type. the loss
tangent is rated at <= 0.005 @ 1kHz.

Sorry, they are PET not polystyrene... my mistake.
https://www.digikey.com/products/en?keywords=495-1119-nd

GH


Polypropylene is generally OK. IIRC Win has some stuff on dielectrics
in AoE3. Polystyrene caps went away because it melts at 100C, which
makes reflow soldering sort of hard unless you're using Wood's metal or
something.
Yeah we use to buy more polypropylene caps. But now all the lower voltage
ones seem to have gone away, so you are stuck with higher voltage (bigger)
ones. I use more COG ceramics.. but they top out at ~ 0.1 uF.
(just went searching DK again for large value cog ceramics)

George H.

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...

Polyphenylene Sulfide is also good as polyproylene at low volatges but
try and get through-hole parts instead of SMD which can deliminate in
reflow.

piglet
 
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