The basic structure of the triode is two reverse-connected PN junctions. The patch triode data shows that there are two combinations of pnp and npn. The three connected terminals are called emitters (emitter,E) and (collector,C) in sequence. The source of the patch triode data is related to their function in triode operation. It also shows the circuit symbols of npn and pnp triodes. The emitter is specially marked. The arrow indicates an extremely n-type semiconductor, which is consistent with the symbol of the diode. When no external bias is applied, both pn-junction surfaces will form a depletion region, separating the neutral p-type region from the n-type region.

The electrical characteristics of triodes are related to the bias voltages of the two pn junctions, and the working intervals are also classified according to the bias modes. Here we first discuss the most commonly used so-called "forward active region" (forward active), in which the pn junction between EB poles is maintained at the forward bias voltage, while the pn junction between BC poles is reverse biased, and triodes commonly used as amplifiers are biased in this way. is a schematic diagram of a pnp triode in this bias region. The depletion region of EB junction will narrow due to forward bias, the potential barrier seen by the carrier will become smaller, the holes of the emitter will be injected into the base, and the electrons of the base will also be injected into the emitter. However, the depletion region of BC junction will widen and the potential barrier seen by the carrier will become larger, so it is non-conductive. The potential energy distribution diagrams of holes and electrons are drawn under the conditions of no applied bias and bias in the forward active region. What is the difference between a triode and two reverse-connected pn diodes? The biggest difference is that the two junctions of the triode are quite close. Taking the pnp triode biased in the forward active region as an example, the holes of the emitter are injected into the n-type neutral region of the base, immediately surrounded by most carrier electrons, then diffuse towards the collector, and are also recombined by electrons. When the holes that are not recombined reach the depletion region of the BC junction, they will be accelerated and swept into the collector by the electric field in this region. The holes are the majority of carriers in the collector and quickly reach the ohmic contact connected to the outside by the drift current to form the collector current IC. The size of the IC has little to do with the magnitude of the reverse bias between the BCs. The exterior of the base only needs to provide the electron flow IBrec of the recombination part with the injected holes, and the electron flow InBE injected into the emitter from the base (this part is the part that the triode function does not need). InB E is combined with the emitter and the hole, I .e. InB E = IErec. The main current types of pnp triode in the forward active region can be clearly seen in fig. 3(a) that the hole flow from the emitter into the base is controlled by the forward bias voltage between EB junction surfaces, similar to the case of diode, near the starting voltage.
The basic structure of the triode is two reverse-connected PN junctions. The patch triode data shows that there are two combinations of pnp and npn. The three connected terminals are called emitters (emitter,E) and (collector,C) in sequence. The source of the patch triode data is related to their function in triode operation. It also shows the circuit symbols of npn and pnp triodes. The emitter is specially marked. The arrow indicates an extremely n-type semiconductor, which is consistent with the symbol of the diode. When no external bias is applied, both pn-junction surfaces will form a depletion region, separating the neutral p-type region from the n-type region.
The electrical characteristics of triodes are related to the bias voltages of the two pn junctions, and the working intervals are also classified according to the bias modes. Here we first discuss the most commonly used so-called "forward active region" (forward active), in which the pn junction between EB poles is maintained at the forward bias voltage, while the pn junction between BC poles is reverse biased, and triodes commonly used as amplifiers are biased in this way. is a schematic diagram of a pnp triode in this bias region. The depletion region of EB junction will narrow due to forward bias, the potential barrier seen by the carrier will become smaller, the holes of the emitter will be injected into the base, and the electrons of the base will also be injected into the emitter. However, the depletion region of BC junction will widen and the potential barrier seen by the carrier will become larger, so it is non-conductive. The potential energy distribution diagrams of holes and electrons are drawn under the conditions of no applied bias and bias in the forward active region. What is the difference between a triode and two reverse-connected pn diodes? The biggest difference is that the two junctions of the triode are quite close. Taking the pnp triode biased in the forward active region as an example, the holes of the emitter are injected into the n-type neutral region of the base, immediately surrounded by most carrier electrons, then diffuse towards the collector, and are also recombined by electrons. When the holes that are not recombined reach the depletion region of the BC junction, they will be accelerated and swept into the collector by the electric field in this region. The holes are the majority of carriers in the collector and quickly reach the ohmic contact connected to the outside by the drift current to form the collector current IC. The size of the IC has little to do with the magnitude of the reverse bias between the BCs. The exterior of the base only needs to provide the electron flow IBrec of the recombination part with the injected holes, and the electron flow InBE injected into the emitter from the base (this part is the part that the triode function does not need). InB E is combined with the emitter and the hole, I .e. InB E = IErec. The main current types of pnp triode in the forward active region can be clearly seen in fig. 3(a) that the hole flow from the emitter into the base is controlled by the forward bias voltage between EB junction surfaces, similar to the case of diode, near the starting voltage.