Small Signal Diode is the type of P-N junction diode which operates on low voltage signals. It is a small non-linear semiconductor device generally used in electronic circuits; its junction area is very tiny. Because of that, the junction has less capacitance & low charge storing capacity. It enables the small-signal diode to have a high switching speed with a very fast recovery time. Many electronic systems use small signals diodes, these can be categorized as AC (continuously varying) signals or a pulse whose amplitude is restricted to a few volts, or in several cases a few milli or even microvolts. Such small signal diodes are used in radio, audio, and video signals as well as digital signals that may be found in the home, in industrial equipment, automotive, aeronautic, and musical systems.
There are various small types of signal diodes available in both wire-ended and surface mount (SMT) formats. They vary from rectifier diodes in some ways; they usually have smaller junction areas giving the junction-less capacitance making them more useful at higher frequencies. High-speed small signal diodes, frequently called switching diodes. They are smaller in size than dedicated power rectifiers and have lower maximum reverse voltage parameters.
Characteristics of Small Signal diode
Peak Reverse Voltage (VPR)
- Peak Reverse Voltage is the maximum reverse voltage that can be applied to the diode before it breaks down.
Reverse Current (IR)
- The Reverse current is the current (very small value) that flows when it is reverse biased.
Maximum Forward Voltage at Peak Forward Current (VF at IF)
Reverse Recovery Time
- Reverse Recovery Time is the time required for reverse current to fall from forwarding current to IR.
V-I Characteristics of a Signal Diode
The direction of conventional current flowing through the diode meaning that the diode will only conduct if a positive supply is connected to the Anode terminal and a negative supply is connected to the Cathode terminal thus only allowing the current to flow through it in one direction only, acting more like a one-way electrical valve, this condition is known as forwarding Biased Condition.
Though we know that if we connect the external energy source in the other direction, the diode will block any current flowing through it, and as an alternative, it will act as an open switch, this condition is known as Reversed Biased Condition.
Forward and Reversed Biased Diode of signal diode biasing
An ideal small signal diode conducts current in one direction (forward-conducting) and blocks current in the other direction (reverse-blocking) is called as forwarding and Reversed Biased Diode of signal diode biasing.
Signal Diodes are used in a wide variety of applications such as switches in rectifiers, current limiters, and voltage snubbers or wave-shaping circuits.
