The flow of electrons is always from anode to cathode outside of the cell or device, regardless of the cell or device type and operating mode, with the exception of diodes, where electrode naming always assumes current in the forward direction ( that of the arrow symbol ), i. e., electrons flow in the opposite direction, even when the diode reverse-conducts either by accident ( breakdown of a normal diode ) or by design ( breakdown of a Zener diode, photo-current of a photodiode or solar cell ).

In a semiconductor diode, the anode is the P-doped layer which initially supplies holes to the junction.

When a positive voltage is applied to anode of the diode from the circuit, more holes are able to be transferred to the depleted region, and this causes the diode to become conductive, allowing current to flow through the circuit.

* In a diode, it is the negative terminal at the pointed end of the arrow symbol, where current flows out of the device.

An exception is when a diode reverse-conducts, either by accident ( breakdown of a normal diode ) or by design ( breakdown of a Zener diode, photo-current of a photodiode or solar cell ).

In a semiconductor diode, the cathode is the N – doped layer of the PN junction with a high density of free electrons as a result of doping, and an equal density of fixed positive charges, which are the dopants that have been thermally ionized.

Like a typical diode, there is a fixed anode and cathode in a Zener diode, but it will conduct current in the reverse direction ( electrons from anode to cathode ) if its breakdown voltage or " Zener voltage " is exceeded.

In most diodes, a white or black painted band identifies the cathode terminal, that is, the terminal that conventional current flows out of when the diode is conducting.

In electronics, a diode is a two-terminal electronic component with asymmetric transfer characteristic, with low ( ideally zero ) resistance to current flow in one direction, and high ( ideally infinite ) resistance in the other.

A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material with a p-n junction connected to two electrical terminals.

A vacuum tube diode, now used only in some high-power technologies and by enthusiasts, is a vacuum tube with two electrodes, a plate ( anode ) and filament ( cathode ).

The most common function of a diode is to allow an electric current to pass in one direction ( called the diode's forward direction ), while blocking current in the opposite direction ( the reverse direction ).

Semiconductor diodes begin conducting electricity only if a certain threshold voltage or cut-in voltage is present in the forward direction ( a state in which the diode is said to be forward-biased ).

The voltage drop across a forward-biased diode varies only a little with the current, and is a function of temperature ; this effect can be used as a temperature sensor or voltage reference.

The diode ( originally a crystal diode ) rectifies the AM radio frequency signal, leaving only the positive peaks of the carrier wave.

From the Shockley ideal diode equation given above, it might appear that the voltage has a positive temperature coefficient ( at a constant current ), but usually the variation of the reverse saturation current term is more significant than the variation in the thermal voltage term.

Vacuum tube diode: electrons from the hot cathode flow towards the positive anode, but not vice versa.

In this mode the diode is often reverse biased ( with the cathode positive ), dramatically reducing the response time at the expense of increased noise.

Above 5. 6 volts, the avalanche effect becomes predominant and exhibits a positive temperature coefficient. TC depending on zener voltage In a 5. 6 V diode, the two effects occur together and their temperature coefficients nearly cancel each other out, thus the 5. 6 V diode is the component of choice in temperature-critical applications.

The diode in series rectifies the incoming signal, allowing current flow only when the positive input terminal is at a higher potential than the negative input terminal.

The two resistors R3 and R4 form a resistive summing circuit with weighted inputs that adds the negative bias voltage V-to the positive diode logic output voltage.

As a result, the unipolar ( positive ) diode output voltage ( about V + for logical one and 1. 0 V for logical zero ) is converted into a bipolar voltage ( a few volts above and below ground ) to drive the output transistor.

When a center-tapped transformer is combined with a bridge ( four diode ) rectifier, it is possible to produce a positive and a negative voltage with respect to a ground at the tap.

A Zener diode connected to ground will protect against positive transients to the value of the Zener breakdown, and will protect against negative transients greater than a normal forward diode drop.

Let an AC voltage of sufficiently large magnitude be superimposed on the dc bias, such that during the positive cycle of the AC voltage, the diode is driven deep into the avalanche breakdown.

In effect, the negative differential resistance of the diode cancels the positive resistance of the load circuit, thus creating a circuit with zero resistance, which will produce spontaneous oscillations.

The negative peaks of the AC waveform are " clamped " to 0 V ( actually − V < sub > F </ sub >, the small forward bias voltage of the diode ) by the diode, therefore the positive peaks of the output waveform are 2V < sub > pk </ sub >.

A spike of positive or negative voltage on an input or output pin of a digital chip, exceeding the rail voltage by more than a diode drop, is a common cause of latchup.

The diode voltage has a negative temperature coefficient ( i. e. it decreases with increasing temperature ), and the junction voltage difference has a positive temperature coefficient.

When the same AC signal reverses polarity, current flows through the second diode filling up the second capacitor with both the positive end from AC source and the first capacitor, charging the second capacitor to twice the charge held in the first.

When the input is positive, it is amplified by the operational amplifier and it turns the diode on.

However since the diode is a one-port ( two terminal ) device, a nonreciprocal component is needed to separate the outgoing amplified signal from the incoming input signal.

A zener diode or resistor may be added between the IC's ground terminal and ground.

Clearly, there is no source of energy in a two terminal diode.

In the Gunn diode, three regions exist: two of them are heavily N-doped on each terminal, with a thin layer of lightly doped material in between.

Because the diode is a one-port ( two terminal ) device, an amplifier circuit must separate the outgoing amplified signal from the incoming input signal to prevent coupling.

This allows the diode to operate at signal frequencies, at the expense of a higher forward voltage drop.

This effect, called Zener breakdown, occurs at a precisely defined voltage, allowing the diode to be used as a precision voltage reference.

Braunstein observed infrared emission generated by simple diode structures using gallium antimonide ( GaSb ), GaAs, indium phosphide ( InP ), and silicon-germanium ( SiGe ) alloys at room temperature and at 77 kelvin.

When the coil is energized with direct current, a diode is often placed across the coil to dissipate the energy from the collapsing magnetic field at deactivation, which would otherwise generate a voltage spike dangerous to semiconductor circuit components.

HiPER requires about 270 kJ of laser energy, so assuming a first-generation diode laser driver at 10 % the reactor would require about 3 MJ of electrical power.

Because they convert electricity into laser light with much higher efficiency, diode lasers also run cooler, which in turn allows them to be operated at much higher frequencies.

Thus, when the device is forward biased, with the p-side at higher electric potential, the diode conducts current easily ; but the current is very small when the diode is reverse biased.

* The beam divergence at an emitting surface, such as that of a light-emitting diode ( LED ), laser, lens, prism, or optical fiber end face.

Increasing the dimensions of the intrinsic region ( and its stored charge ) allows the diode to look like a resistor at lower frequencies.

* Schottky TTL ( S ), introduced in 1969, which used Schottky diode clamps at gate inputs to prevent charge storage and improve switching time.

An example is the p-n junction diode ( curve at right ).

However, in some diode applications, the AC signal applied to the device is small and it is possible to analyze the circuit in terms of the dynamic, small-signal, or incremental resistance, defined as the one over the slope of the V – I curve at the average value ( DC operating point ) of the voltage ( that is, one over the derivative of current with respect to voltage ).

The computer knows that if the diode detects light as it is drawing a square ( or after the screen refreshes ) then, that is the target at which the gun is pointed.

Essentially, the diode tells the computer whether or not the player hit something, and for < var > n </ var > objects, the sequence of the drawing of the targets tell the computer which target the player hit after 1 + ceil ( log < sub > 2 </ sub >(< var > n </ var >)) refreshes ( one refresh to determine if any target at all was hit and ceil ( log < sub > 2 </ sub >(< var > n </ var >)) to do a binary search for the object that was hit ).

From that point on, the relatively low impedance of the diode keeps the voltage across the diode at that value.

The infrared diode modulates at a speed corresponding to a particular function.

When the emitter voltage is driven approximately one diode voltage above the voltage at the point where the P diffusion ( emitter ) is, current will begin to flow from the emitter into the base region.