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Class-C amplifier is the one biased so that the output current is zero for more than one half of an input sinusoidal signal cycle. Figure 2.5 illustrates the operation of the class-C
Lecture 22: Class C Power Amplifiers. We discovered in Lecture 18 (Section 9.2) that the maximum efficiency of Class A amplifiers is 25% with a resistive load and 50% with a transformer-coupled resistive load. Also, Class A amplifiers dissipate energy (in the transistor) even when there is no RF output signal! (Why?)
RF Power Amplifiers are used in a wide variety of applications including Wireless Communication, TV transmissions, Radar, and RF heating. The basic techniques for RF power amplification can use classes as A, B, C, D, E, and F, for frequencies ranging from VLF (Very Low Frequency) through Microwave Frequencies.
A performance comparison was made of the 2N3948 operating at 300 MHz as a Class A small-signal amplifier, and as a Class C* power amplifier delivering a power output of 1 W. Table 1 shows the results of this comparison. The most striking difference in this comparison is in the device input impedance.
Radio frequency amplifiers used in transmitters can be required to produce thousands of kilowatts of output power, and DC amplifiers used in electronic control systems may also need high power outputs to drive motors or actuators of many different types.
Class C Formulas. Transistor Power. Draw a schematic of class B/AB push-pull amplifier and explain its operation. Determine the efficiency of transistor power amplifiers. Discuss the factors that limit the power rating of a transistor and what can be done to improve the power rating. GOOD TO KNOW. 12-1 Amplifier Terms.
Power Amplifiers Many applications do not require linear RF amplification and can therefore make use of the greater efficiency and simplicity offered by Class C tuned power amplifiers. Such applications include amplification of C W, FM, and AM (double-sideband, full-carrier) signals. The CW and FM signals have at
