Hi Sandeep

it is a passive one. the non linear behavior is due to Schottky contact, which is different to ohmic one.

hope this help

Sandeep go through this ..i guess u will be able to think it other way round...though it is passive

@Ems Narayanan: Can you show us an application using a diode as an active part?

@Shaikh Imtiyaz: I didn`t yet go through the linked paper, however, can you please answer the following question:

What are the input resp. the output signals of a diode acting as an amplifier?

Thank you.

Sir the entire analysis is with d-c input and output response is in terms of d.c shift in cro or voltage.

...and this is equivalent to "amplification"? Which quantity is amplified?

Sir diode being two terminal device so the only input is d.c input in case now this amplification can be seen in two manner

1) incremental output d.c voltage

2) or very high internal additive voltage

Dear colleagues !

Thank you Sandeep for inviting me to share in answering this question. A diode is a two terminal device having two electrodes, the anode and the cathode.There are many types of diodes according to their physical structure. The conventional rectifier diode is a pn junction diode. It acts as a polarity switch such that it will be on when it is forward biased and off when it is reverse biased. The i-v characteristics is nonlinear and follows the relation I=Is(e^(V/Vt -1) with Is the reverse saturation current and Vt the thermal voltage.This characteristic is well known. The most important notice that the i-v curve is monotonic and does not contain a negative differential resistance.

In order to be able to amplify small signals or to generate oscillations a two terminal device, i,e, a diode, must have a negative differential resistance. In this case the diode will be active. Since the conventional diode has no negative differential resistance it will not be active and since it dissipates electrical energy it can be considered as a passive element.

The M-S schottky rectifier diode behaves as the conventional pn rectifier diode.

If the doping concentration on both sides of the pn junction is increased to the degeneracy limit a tunnel diode is produced. Because of the additional tunneling current the iv characteristics will have the so called N-Shape containing a negative differential resistance.T he tunnel diode is used to amplify and generate microwave signals.

There are also microwave diodes such as the Gunn diode and the IMPATT diode which shows negative differential resistance and accordingly they are considered active devices.

In summary, the diode will be active when it has a negative differential resistance, other wise it is passive. Having negative resistance the diode will be capable of amplifying and generating signals.

For more details consult the book: S M Sze, Physics of semiconductor devices.

Thank you

@ Abdelhalim Zekry,

thank you for this clarification that appears to be necessary.

Maybe we should first answer the question, "What is passive and what active in electronics?"

https://www.researchgate.net/post/What_is_passive_and_what_active_in_electricity_and_electronics_Can_we_make_passive_elements_become_less_passive_neutral_or_even_active?

https://www.researchgate.net/post/Is_a_transistor_really_an_amplifying_element_Is_it_an_active_or_passive_device_Are_there_amplifying_elements_Is_it_possible_to_amplify_energy_at_all

and then to see what the diode is (for a company of the diode, we can look in parallel and a transistor:)

So, if we assume that the active element is the one that contains а source: the ordinary diode is passive but the photodiode is active; the transistor is passive.

If we assume that the active element is the one that can electrically controll the electrical power: the ordinary diode is passive, the photodiode is passive as well but the transistor is active.

And finally, if you look at any textbook on basic electronics, and you see the constant voltage source (with Vf = 0,7 V) in the diode equivalent circuit, you can reach the conclusion that the ordinary diode is also an active element:) Here is an example:

http://www.nptel.iitm.ac.in/courses/Webcourse-contents/IIT-ROORKEE/BASIC-ELECTRONICS/lecturers/lecture_4/lecture4_page1.htm

Regards, Cyril

Shaikh, congratulations on your desire to invent a new kind of amplifier! Еven if you fail, moving towards that goal, you can make а real invention... But we have a lot to talk with you about your arrangement.

1. IMO even in the case of a high DC supply voltage, there is no current flowing through your circuit because of the high- ("infinite-") resistive voltmeter. So the diode is cut-off; its high-resistance rd and the "infinite" voltmeter resistance Rv form a voltage divider with a transfer ratio of almost 1 (if you look at the forward-biased diode IV curve in the picture below, you will see that when there is no current passing, there is no voltage across the diode).

2. I can not understand how this 1.5 V appeared across the diode when the supply voltage is 0 V?

3. And finally, what is the input and what the output of this "amplifier"? Where is the gain (a ratio > 1) here? Do you know that amplifiers amplify power (not either voltage or current?

You can see also our discussions in the related question below

https://www.researchgate.net/post/Voltage_or_current_controlled_device_is_a_BJT_And_what_does_voltage_controlled_and_current_controlled_mean_Is_this_a_property_of_the_BJT

Regards, Cyril

Cyril thanx i attatching some thing here which i guess will give rest to few of your question

Cyril you can the arrnagement yourself and at 0v you will see the current also at the output terminal of diode where we taking voltage..regrds

Diode is a active element because it will have internal energy at the time of manufacturing. so active elements are those elements which have internal energy at the time of manufacturing e.g all types of sources,diode, transistors and SCR family etc.

Reading all the answers above, my impression is that there are different definitions about "active" and "passive". On the other hand, is such a classification really necessary? Does it help to increase knowledge?

No Lutz, I think it is not "really necessary"... but it is absolutely necessary to answer the "provocative" statements above that are contrary to our notions of the world:

Ems: "Any device, which is nfluenced by external forces by its terminals or otherwise, to change its fundamental properties" - then, is a thermistor... and any generating transducer, an active device as well?

Ems: "Depends upon the application" (i.e., the diode can be either active or passive)

Shaikh: "vdd = 0v and vk = 1.51V and vak = 1.51v" that simply means "the voltage across a diode is 1.51 V without applying any supplying voltage" or simply, "the diode produces voltage"

Ashok: "Diode is a active element because it will have internal energy at the time of manufacturing."

As for me, I would accept that any electrical element that "reacts" to the change in the input quantity (e.g., voltage, current...) by changing some of its properties (e.g., resistance) is active. Then all types of nonlinear (dynamic) resistors (including diodes) would be active devices.

But it is now accepted only those devices, which react with a sufficient "vigor" to the input "intervention" so that to obtain a "gain", to be considered as active... and these are the negative differential resistors...

Other devices (circuits) react to the input "intervention" by including and "vigorously" varying the voltage of an additional supplying voltage source... and these are the true negative resistors...

The two types of elements above are active since they are "self-variable". Besides them, constant sources are considered as active ones since they can produce energy. Maybe, in this way, they react to the passivity of the passive elements:)... so they are also varying elements?

This is the typical BJT behavior - to act as a constant-current non-linear resistor.

About the link above

http://www.researchgate.net/go.Deref.html?url=http%3A%2F%2Fwiki.answers.com%2FQ%2FWhy_diode_is_active_device_when_all_other_active_devices_require_external_power_supply

It seems there are two types of switches - a "passive switch" (a diode) and an "active switch" (a transistor)...:) The passive switch does not amplify the power (Pout = Pin) while the active switch amplifies the power Pout > Pin). Do not take these thoughts too seriosly:)

Even if i accept that diode have internal charge additive energy then i request one available here to kindly go through every readings which i have noted you will see that at some point of time the output voltage is also less than input...whats that????????? I guess whether amplifier or active device i must get some pat for noting that behaviour

Shaikh, each amplifying arrangement is composed of three components: an input voltage source, a controlling element (a transistor), a power supply (a constant voltage source) and a load. What (where) are these elements in your arrangement?

Cyril i agrees with you...but what the name you want to suggest to device whose is able to either follow the input or giving higher out put for certain input. Now i do not agree with believe that voltage inside diode is responsible for above behavior bec if that the case then the there must be some better explanation to decrease in output in my observation

Dear Shaikh,

I can agree that the output of your device (1N4007) can follow the input when it is unloaded (open circuit) but I cannot imagine how it will "give higher output for certain input". I repeat my request: I want to know what is input and what is output in your "amplifying" arrangement.

Regards, Cyril

@Abdelhalim Zekry, Cyril Mechkov, EMS Narayanan, Lutz von Wangenheim, Shaikh Imtiyaz - thank you very much for your valuable comments ....

Sandeep i guess i too did contributed may be less than others though lol

all the semiconductor and their devices are active elements in the electronic circuit,

Dear Narayanan the active elements are those that can enhance the signal in the electronic circuit. For example semiconductor conductivity increase with increase in temperature. So it is active.

If you apply the temperature to the conductor its conductivity decreases but not that much because it already have large conductivity. Thats why we used conductors as an electrodes because they are passive. We never use semiconductors or their devices as electrodes.

Even if you apply a voltage to the single diode, its shows you rectifying behavior.

Quote: "For example semiconductor conductivity increase with increase in temperature. So it is active."

With the same logic you could say: Each resistor is an active element because its resistance changes with temperature. I am not sure if this is really a valid criterion to distinguish between active and passive.

Perhaps it is "active", but not enough:)?

So many definition for properties: PASSIVE AND ACTIVE.

It seems to me that answer is not in Electronic but in Circuit Theory. I liked Cyril question and efforts in this topic. But, maybe is bemused construction "passive device"? In Circuit Theory the properties PASSIVE and ACTIVE is defined for the model of component or device. So, for dissipative elements ( I consider that model of rectifier diode is represented by ideal or real diode) the properties of passive or active is determined by product of voltage and current of v-i characteristic. If is product (v*i)

Every diode has a threshold voltage within itself, hence it can be called as an active device. On the other hand a diode doesn't work unless and until it is biased with a supply, hence it can be called as a passive device too.

P-n junction diode is an active device.It consists of 2 layers, P-type & n-type.Holes are the majority charge carriers in P-type & electrons are Majority charge carrier. When it is reverse biased then a thick depletion layer of immobile ions are present.

It has +ve resistance of coefficient so there is no problem of secondary breakdown.And parallel operation is also possible.In rectifier circuit, during +ve half as well as -ve half of i/p signal voltage, o/p votage is fixed and +ve. It has some amplification capability.

Thank you everyone ...

Passive. Non-linear, but passive.

@EMS Narayan

Complementing what Abdelhalim Zekry said above...

If you use as definition that passive components as ones that cannot supply energy themselves, then in DC, if they are in the first or third quadrants only on the I x V curve, which diodes are, then they are passive. If you consider AC, then think of di x dv curve and tunnel diodes become active (on a short transient), but in DC they are also passive.

@Denis Pelin, I like your definition of active and passive, but the crux of the question is on the interpretation of DC and AC behaviour. The product of I*V (in DC behaviour) for the tunnel diode is always positive. It is just the di*dv (AC behaviour) that can it be negative in certain areas of the curve (negative slope).

@EMS Narayanan,

I agree with you. As I said, it depends on the definitions of 'active' / 'passive' that one uses! :-)

Best wishes

EMS Narayanan, I would like to comment your assertion "I can operate a switch in a passive mode, but, it is an active device. The same argument goes for diodes."

I can agree that all kinds of 4--terminal (e.g., relays) and 3-terminal (e.g., transistors) switching elements are active devices since they allow to control big power by many times less power (what is the widespread definition of an active device).

But in the case of the exotic 2-terminal diode switch, the magnitudes of the input and output power are the same. So, there is no amplification and the diode should be classified as a passive device.

BTW, the sorry fact that the input and the output of the diode switch is the same, has caused many problems when using diodes as switches; see for example my question about "diode-based" logic gates:

https://www.researchgate.net/post/What_is_the_basic_idea_of_the_input_logical_part_of_transistor-transistor_TTL_diode-transistor_DTL_and_diode_DL_logic_gates_Are_they_related

Regards, Cyril

But yet, does "active function" mean "amplification" (Pout > Pin)?

Far as I know, "back-to-back diode" is a formal model of the bipolar transistor since there is no connection between the operation of the two diodes. Here is an example of a "back-to-back LED" but it is not an active element (a LED transistor:)

http://www.circuit-fantasia.com/ResearchGate/LEDTL.AVI

Quote EMS Narayanan: "Just for example, I can use a back-to-back diode as a transistor, which then becomes an active element in combination."

Can you really? I cannot.

Did you try it? Do you know how a BJT really works?

Finally, we should make a conclusion to close the issue. So, what is a diode - an active or passive device?

Encyclopedia:)

 I am agree to above comments. can you say diode (1N4148)  is active or passive device?

The product v*i is not negative for the tunnel diode. What can be negative is dv*di.

In parametric amplifier, every diode with junction capacitance depending on bias voltage is an active device, converting power on pumping frequency to the power of the signal.  In rectifier, extra power is needed to overcome the forward threshold voltage so the diode is definetely passive.

Whether diode is active or passive depends on the circuit.