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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]
A classic Emerson transistor radio, circa 1958. A transistor radio is a small portable radio receiver that uses transistor-based circuitry. Previous portable radios used vacuum tubes, which were bulky, fragile, had a limited lifetime, consumed excessive power and required large heavy batteries.
The Regency TR-1, which used Texas Instruments' NPN transistors, was the world's first commercially produced transistor radio in 1954. Size: 3×5×1.25 inch (7.6×12.7×3.2 cm) Following development of transistor technology, bipolar junction transistors led to the development of the transistor radio.
The TR-1 is a superheterodyne receiver [2] [11] with four n-p-n germanium transistors and one diode. It contains a single transistor converter stage, followed by two intermediate-frequency amplifier stages. After detection, a single-transistor stage amplifies the audio frequency. All amplifier stages use common emitter amplifiers. Stages are ...
The first discrete-transistor audio amplifiers barely supplied a few hundred milliwatts, but power and audio fidelity gradually increased as better transistors became available and amplifier architecture evolved. [94] Modern transistor audio amplifiers of up to a few hundred watts are common and relatively inexpensive.
The common base current gain (or α) of a point-contact transistor is usually around 2 to 3, [4] whereas α of bipolar junction transistor (BJT) cannot exceed 1. The common emitter current gain (or β) of a point-contact transistor does not usually exceed 1, [4] whereas β of a BJT is typically between 20 and 200. Negative differential ...
The Early effect in bipolar junction transistors is named after Jim Early, who first characterized it and published a paper on it in 1952. [1] The Early effect in bipolar junction transistors is due to an effective decrease in the base width because of the widening of the base-collector depletion region, resulting in an increase in the ...
In analog devices, the floating body effect is known as the kink effect. One countermeasure to floating body effect involves use of fully depleted (FD) devices. The insulator layer in FD devices is significantly thinner than the channel depletion width. The charge and thus also the body potential of the transistors is therefore fixed. [1]