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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]
All cathodes are connected to the output, which has a pull-down resistor. If any input is high, its diode will be forward-biased and conduct current, and thus pull the output voltage high [b]. If all inputs are low, all diodes will be reverse-biased and so none will conduct current. The pull-down resistor will quickly pull the output voltage low.
Various semiconductor diodes. Left: A four-diode bridge rectifier. Next to it is a 1N4148 signal diode. On the far right is a Zener diode. In most diodes, a white or black painted band identifies the cathode into which electrons will flow when the diode is conducting. Electron flow is the reverse of conventional current flow. [2] [3] [4]
It can be converted to a Schmitt trigger by connecting an additional base resistor R to one of the inputs (Q1's base in the figure). The two resistors R and R 4 form a parallel voltage summer (the circle in the block diagram above) that sums output (Q2's collector) voltage and the input voltage, and drives the single-ended transistor ...
A resistor at a certain temperature has a thermal noise associated with it. A noise generator might have two resistors at different temperatures and switch between the two resistors. The resulting output power is low. (For a 1 kΩ resistor at room temperature and a 10 kHz bandwidth, the RMS noise voltage is 400 nV. [3])
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 ...
The load line diagram at right is for a resistive load in a common emitter circuit. The load line shows how the collector load resistor (R L) constrains the circuit voltage and current. The diagram also plots the transistor's collector current I C versus collector voltage V CE for different values of base current I base.
When more accuracy is desired in modelling the diode's turn-on characteristic, the model can be enhanced by doubling-up the standard PWL-model. This model uses two piecewise-linear diodes in parallel, as a way to model a single diode more accurately. PWL Diode model with 2 branches. The top branch has a lower forward-voltage and a higher ...