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An alternative, which is used for voltage references that need to be highly stable over long periods of time, is to use a Zener diode with a temperature coefficient (TC) of +2 mV/°C (breakdown voltage 6.2–6.3 V) connected in series with a forward-biased silicon diode (or a transistor B–E junction) manufactured on the same chip. [4]
Many electronic devices, such as diodes, transistors and vacuum tubes, whose function is processing time-varying signals, also require a steady (DC) current or voltage at their terminals to operate correctly. This current or voltage is called bias. The AC signal applied to them is superposed on this DC bias current or voltage.
In electronics, the Zener effect (employed most notably in the appropriately named Zener diode) is a type of electrical breakdown, discovered by Clarence Melvin Zener. It occurs in a reverse biased p-n diode when the electric field enables tunneling of electrons from the valence to the conduction band of a semiconductor , leading to numerous ...
In the Zener diode, the concept of PIV is not applicable. A Zener diode contains a heavily doped p–n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is "clamped" to a known value (called the Zener voltage), and avalanche does not ...
PN junction operation in forward-bias mode, showing reducing depletion width. In forward bias, the p-type is connected with a positive electrical terminal and the n-type is connected with a negative terminal. The panels show energy band diagram, electric field, and net charge density. The built-in potential of the semiconductor varies ...
A bias voltage between the diode and ground offsets the output voltage by that amount. For example, an input signal of peak value 5 V (V INpeak = 5 V) is applied to a positive clamp with a bias of 3 V (V BIAS = 3 V), the peak output voltage will be: V OUTpeak = 2 × V INpeak + V BIAS V OUTpeak = 2 × 5 V + 3 V V OUTpeak = 13 V
Depending on the voltage level of each input and direction of the diode, each diode may or may not be forward-biased. If any are forward-biased, the shared output wire will be one small forward voltage drop within the forward-biased diode's input. If no diode is forward-biased then no diode will provide drive current for the output's load (such ...
Severely overloaded Zener diodes in reverse bias shorting. A sufficiently high voltage causes avalanche breakdown of the Zener junction; that and a large current being passed through the diode causes extreme localised heating, melting the junction and metallisation and forming a silicon-aluminium alloy that shorts the terminals.