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A transistor is a semiconductor device used to amplify or switch electrical signals and power. It is one of the basic building blocks of modern electronics. [1]
The transistor count is the number of transistors in an electronic device (typically on a single substrate or silicon die).It is the most common measure of integrated circuit complexity (although the majority of transistors in modern microprocessors are contained in cache memories, which consist mostly of the same memory cell circuits replicated many times).
NMOS transistors operate by creating an inversion layer in a p-type transistor body. This inversion layer, called the n-channel, can conduct electrons between n-type source and drain terminals. The n-channel is created by applying voltage to the third terminal, called the gate .
In field-effect transistors (FETs), depletion mode and enhancement mode are two major transistor types, corresponding to whether the transistor is in an on state or an off state at zero gate–source voltage. Enhancement-mode MOSFETs (metal–oxide–semiconductor FETs) are the common switching elements in most integrated circuits.
The introduction of the transistor is often considered one of the most important inventions in history. [1] [2] Transistors are broadly classified into two categories: bipolar junction transistor (BJT) and field-effect transistor (FET). [3] The principle of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925. [4]
The invention of the high-electron-mobility transistor (HEMT) is usually attributed to physicist Takashi Mimura (三村 高志), while working at Fujitsu in Japan. [4] The basis for the HEMT was the GaAs (gallium arsenide) MOSFET (metal–oxide–semiconductor field-effect transistor), which Mimura had been researching as an alternative to the standard silicon (Si) MOSFET since 1977.
The input signal is applied across the ground and the base circuit of the transistor. The output signal appears across ground and the collector of the transistor. Since the emitter is connected to the ground, it is common to signals, input and output. The common-emitter circuit is the most widely used of junction transistor amplifiers.
For NPN open collector outputs, the emitter of the NPN transistor is internally connected to ground, [1] so the NPN open collector internally forms either a short-circuit (technically low impedance or "low-Z") connection to the low voltage (which could be ground) when the transistor is switched on, or an open-circuit (technically high impedance ...