# "reverse diode"

Started by July 9, 2012
```Is there a passive device similar to a diode that has low impedance at 0 fo=
rward voltage and high impedance at some larger voltage?

e.g., flip the diode curve horizontally then center the knee of the several=
hundred mV above 0V.

One can emulate such a device a number of ways more or less but can one be =
made based on fundamental physical principles so that it behaves very simil=
ar to a "reverse diode"(by which I do not mean a reverse biased diode... so=
please do not conflate the two).

Is there any simple reason why such a semiconductor based device can not ex=
ist? i.e., Is it possible to have a semiconductor device with an IV curve t=
hat **looks** like I(V) =3D 1/V or 1/V^2?

```
```On Sun, 8 Jul 2012 22:11:05 -0700 (PDT), "jon.jukoba@gmail.com"
<jon.jukoba@gmail.com> wrote:

>e.g., flip the diode curve horizontally then center the
>knee of the several hundred mV above 0V.

There will always be a junction potential to overcome.
```
```On 2012-07-09, jon.jukoba@gmail.com <jon.jukoba@gmail.com> wrote:
> Is there a passive device similar to a diode that has low impedance
> at 0 forward voltage and high impedance at some larger voltage?

1N5309

> e.g., flip the diode curve horizontally then center the knee of the several hundred mV above 0V.

could be tricky.

>
> One can emulate such a device a number of ways more or less but can one be made based on fundamental physical principles so that it behaves very similar to a "reverse diode"(by which I do not mean a reverse biased diode... so please do not conflate the two).
>
> Is there any simple reason why such a semiconductor based device can not exist? i.e., Is it possible to have a semiconductor device with an IV curve that **looks** like I(V) = 1/V or 1/V^2?
>

--
&#9858;&#9859; 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---
```
```On 2012-07-09, Chieftain of the Carpet Crawlers <theslipperman@thebarattheendoftheuniverse.org> wrote:
> On Sun, 8 Jul 2012 22:11:05 -0700 (PDT), "jon.jukoba@gmail.com"
><jon.jukoba@gmail.com> wrote:
>
>>e.g., flip the diode curve horizontally then center the
>>knee of the several hundred mV above 0V.
>
>   There will always be a junction potential to overcome.

in a JFET?

--
&#9858;&#9859; 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---
```
```On 9 Jul 2012 08:53:12 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

>On 2012-07-09, Chieftain of the Carpet Crawlers <theslipperman@thebarattheendoftheuniverse.org> wrote:
>> On Sun, 8 Jul 2012 22:11:05 -0700 (PDT), "jon.jukoba@gmail.com"
>><jon.jukoba@gmail.com> wrote:
>>
>>>e.g., flip the diode curve horizontally then center the
>>>knee of the several hundred mV above 0V.
>>
>>   There will always be a junction potential to overcome.
>
>in a JFET?

In a DIODE junction.  Learn to read.
```
```On Monday, July 9, 2012 7:11:05 AM UTC+2, jon wrote:
> Is there a passive device similar to a diode that has low impedance at 0 =
forward voltage and high impedance at some larger voltage?
>=20
> e.g., flip the diode curve horizontally then center the knee of the sever=
al hundred mV above 0V.
>=20
> One can emulate such a device a number of ways more or less but can one b=
e made based on fundamental physical principles so that it behaves very sim=
ilar to a "reverse diode"(by which I do not mean a reverse biased diode... =
so please do not conflate the two).
>=20
> Is there any simple reason why such a semiconductor based device can not =
exist? i.e., Is it possible to have a semiconductor device with an IV curve=
that **looks** like I(V) =3D 1/V or 1/V^2?

Probably not, but search on the tunnel diode, which does have a distinctly =
kinky I(V) curve.

http://en.wikipedia.org/wiki/Tunnel_diode

http://www.electronicsurplus.com/item/8168/

--=20
Bill Sloman, Nijmegen
```
```wrote in message=20

> Is there a passive device similar to a diode that has low
> impedance at 0 forward voltage and high impedance at
> some larger voltage?

> e.g., flip the diode curve horizontally then center the knee
> of the several hundred mV above 0V.

> One can emulate such a device a number of ways more or
> less but can one be made based on fundamental physical
> principles so that it behaves very similar to a "reverse diode"
> (by which I do not mean a reverse biased diode... so please
> do not conflate the two).

> Is there any simple reason why such a semiconductor based
> device can not exist? i.e., Is it possible to have a semiconductor
> device with an IV curve that **looks** like I(V) =3D 1/V or 1/V^2?

A PTC current limiting fuse acts something like this. Also a tungsten =
lamp.

If it does not need to be reversible a fuse would fit this definition.

A tunnel diode may also be similar but it needs to be biased, and then =
it=20
has negative resistance.

Is there a proposed application for a device having this property?

Paul=20

```
```On 07/09/2012 07:14 AM, P E Schoen wrote:
> wrote in message
>
>> Is there a passive device similar to a diode that has low
>> impedance at 0 forward voltage and high impedance at
>> some larger voltage?
>
>> e.g., flip the diode curve horizontally then center the knee
>> of the several hundred mV above 0V.
>
>> One can emulate such a device a number of ways more or
>> less but can one be made based on fundamental physical
>> principles so that it behaves very similar to a "reverse diode"
>> (by which I do not mean a reverse biased diode... so please
>> do not conflate the two).
>
>> Is there any simple reason why such a semiconductor based
>> device can not exist? i.e., Is it possible to have a semiconductor
>> device with an IV curve that **looks** like I(V) = 1/V or 1/V^2?
>
> A PTC current limiting fuse acts something like this. Also a tungsten lamp.
>
> If it does not need to be reversible a fuse would fit this definition.
>
> A tunnel diode may also be similar but it needs to be biased, and then
> it has negative resistance.
>
> Is there a proposed application for a device having this property?
>
> Paul

Sure thing.  A depletion FET with gate and source connected, or a
classical two-terminal BJT current limiter.  (Series pass transistor,
base connected to collector via big R, sense transistor's BE connected
across a sense resistor steals base current when the drop across the
sense resistor reaches V_BE.)

You can add foldback, so that the current decreases at increasing delta-V.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net
```
```On Sun, 8 Jul 2012 22:11:05 -0700 (PDT), "jon.jukoba@gmail.com"
<jon.jukoba@gmail.com> wrote:

>Is there a passive device similar to a diode that has low impedance at 0 forward voltage and high impedance at some larger voltage?
>
>e.g., flip the diode curve horizontally then center the knee of the several hundred mV above 0V.
>
>One can emulate such a device a number of ways more or less but can one be made based on fundamental physical principles so that it behaves very similar to a "reverse diode"(by which I do not mean a reverse biased diode... so please do not conflate the two).
>
>Is there any simple reason why such a semiconductor based device can not exist? i.e., Is it possible to have a semiconductor device with an IV curve that **looks** like I(V) = 1/V or 1/V^2?
>

http://www.analog-innovations.com/SED/PerfectDiodeForChargerIsolation.pdf

...Jim Thompson
--
| James E.Thompson, CTO                            |    mens     |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

I love to cook with wine.     Sometimes I even put it in the food.
```
```jon.jukoba@gmail.com wrote:
> Is there a passive device similar to a diode that has low impedance at 0 forward voltage and high impedance at some larger voltage?
>
> e.g., flip the diode curve horizontally then center the knee of the several hundred mV above 0V.
>
> One can emulate such a device a number of ways more or less but can one be made based on fundamental physical principles so that it behaves very similar to a "reverse diode"(by which I do not mean a reverse biased diode... so please do not conflate the two).
>
> Is there any simple reason why such a semiconductor based device can not exist? i.e., Is it possible to have a semiconductor device with an IV curve that **looks** like I(V) = 1/V or 1/V^2?
>
>
If you are not too picky about voltages, an Esaki diode has low Z at
and near 0V, and then the Z increases at the valley...
```