Tag: Free Book on Semiconductors
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13.3 The Triode
De Forest’s Audion tube came to be known as the triode tube because it had three elements: filament, grid, and plate (just as the “di” in the name diode refers to two elements: filament, and plate). Later developments in diode tube technology led to the refinement of the electron emitter: instead of using the filament…
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13.2 Early Tube History
Thomas Edison, that prolific American inventor, is often credited with the invention of the incandescent lamp. More accurately, it could be said that Edison was the man who perfected the incandescent lamp. Edison’s successful design of 1879 was actually preceded by 77 years by the British scientist Sir Humphry Davy, who first demonstrated the principle…
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13.1 Introduction to Electron Tubes
An often neglected area of study in modern electronics is that of tubes, more precisely known as vacuum tubes or electron tubes. Almost completely overshadowed by semiconductor, or “solid-state” components in most modern applications, tube technology once dominated electronic circuit design. In fact, the historical transition from “electric” to “electronic” circuits really began with tubes,…
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9.8 Measurement Circuits
Figure below shows a photodiode amplifier for measuring low levels of light. Best sensitivity and bandwidth are obtained with a trans-impedance amplifier, a current to voltage amplifier, instead of a conventional operational amplifier. The photodiode remains to reverse biased for lowest diode capacitance, hence wider bandwidth, and lower noise. The feedback resistor sets the “gain”,…
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9.7 Computational Circuits
When someone mentions the word “computer,” a digital device is what usually comes to mind. Digital circuits represent numerical quantities in binary format: patterns of 1’s and 0’s represented by a multitude of transistor circuits operating in saturated or cutoff states. However, analog circuitry may also be used to represent numerical quantities and perform mathematical…
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9.6 Radio Circuits
(a) Crystal radio. (b) Modulated RF at antenna. (c) Rectified RF at diode cathode, without C2 filter capacitor. (d) Demodulated audio to headphones. An antenna ground system, tank circuit, peak detector, and headphones are the main components of a crystal radio seen in figure (a). The antenna absorbs transmitted radio signals (b) which flow…
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9.4 Oscillator Circuits
Phase shift oscillator. R1C1, R2C2, and R3C3 each provide 60° of phase shift. The phase shift oscillator of the figure above produces a sine wave output in the audio frequency range. Resistive feedback from the collector would be negative feedback due to 180° phasing (base to collector phase inversion). However, the three 60° RC…
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9.3 Amplifier Circuits
Note, Q3 and Q4 in the figure below are complementary, NPN and PNP respectively. This circuit works well for moderate power audio amplifiers. For an explanation of this circuit see “Directly coupled complementary-pair,” Ch 4. Direct coupled complementary symmetry 3 w audio amplifier Back to Main Index of Book
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9.2 Power Supply Circuits
There are three major kinds of power supplies: unregulated (also called brute force), linear regulated, and switching. The fourth type of power supply circuit called the ripple-regulated, is a hybrid between the “brute force” and “switching” designs, and merits a subsection to itself. Unregulated An unregulated power supply is the most rudimentary type, consisting of…
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9.1 ElectroStatic Discharge
At the start of this book, we discussed static electricity and how it is created. This has a lot more significance than might be first assumed, as the control of static electricity plays a large part in modern electronics and other professions. An ElectroStatic Discharge event is when a static charge is bled off in…
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8.15 Op-Amp Data
Parametric data for all semiconductor op-amp models except the CA3130 comes from National Semiconductor’s online resources, available at this website: [*]. Data for the CA3130 comes from Harris Semiconductor’s CA3130/CA3130A datasheet (file number 817.4). Back to Main Index of Book
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8.14 Operational Amplifier Models
While mention of operational amplifiers typically provokes visions of semiconductor devices built as integrated circuits on a miniature silicon chip, the first op-amps were actually vacuum tube circuits. The first commercial, general purpose operational amplifier was manufactured by the George A. Philbrick Researches, Incorporated, in 1952. Designated the K2-W, it was built around two twin-triode…
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8.13 Op-Amp Practical Considerations
Real operational amplifiers have some imperfections compared to an “ideal” model. A real device deviates from a perfect difference amplifier. One minus one may not be zero. It may have have an offset like an analog meter which is not zeroed. The inputs may draw current. The characteristics may drift with age and temperature. Gain…