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SECTION 1---BASIC VARACTOR THEORY What Is a Varactor? - Varactor Semiconductor Fundamentals-The PN Junction-Junction Operation-Inside The Varactor-Varactor Ratings-Types of Varactors SECTION 2---VARACTOR OPERATION Voltage and Current Response-Multiple Operation-Varactor and Conventional Capacitor in Combination-Varactor Tuned Circuits-Varactor As Frequency Multiplier SECTION 3---RECEIVER APPLICATIONS Tuning Requirements and Considerations - Automatic Frequency Control-R-F Amplifier ( Preselector) SECTION 4---TRANSMITTER APPLICATIONS Tank Tuning-Frequency Multipliers-Frequency Modulation-Amplitude Modulation-R-F Output Control SECTION 5---VARACTOR AMPLIFIERS Basic Principles-Resonant-Slope Amplifiers-Parametric Amplifier-D-C Amplifier SECTION 6---INSTRUMENT APPLICATIONS Absorption Wavemeter-Remote-Tuned Field-Strength Meter-Harmonic Intensifier for Frequency Standard-R-F Sweep Oscillator-Signal Converter-Electronic D-C Voltmeter SECTION 7---SUPPLEMENTARY APPLICATIONS Frequency Divider - Microwave Limiter - Wave Filters - Voltage-Tuned Pi Network-Balanced Modulator-Ultrahigh Resistance Switch-Capacitive Potentiometer-Light-Controlled Capacitor-Negative Reactor-Varactor Effects in Conventional Diodes Preface The varactor, while no youngster, is a comparative new comer [ca 1966] to the semiconductor field. But with the vigor of youth it has already extended dependable solid-state operation into the microwave spectrum, and it has simplified and improved several types of electronic circuits. This is all the more remarkable because the varactor is a simple two-terminal device. From one standpoint the varactor is the fulfilled hope of early workers that somehow the semiconductor diode might be made to amplify, multiply, and switch signals by itself unaided by other electrodes or even by the property of negative resistance. It is also the answer to the long-felt need for a simple device which can convert voltage changes into useful amounts of capacitance change at high Q and with good temperature stability. Despite its novel features and dramatic performance, the varactor is no laboratory curiosity. It has taken its place in the ranks of workhorse electronic components and promises to assume increased future importance. Research and development continue in varactor design and applications. This guide attempts to explain the varactor and to describe some of its applications, in essentially non-mathematical language. The author hopes that the discussion will help electronics people of all classes to understand this device and to use it advantageously. -RPT also see:
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