electronics

frequency stability The frequency stability of an oscillator is the amount by which its frequency drifts from the desired value. It is desirable that any frequency drift should be very small and the maximum allowable change in frequency is normally specified as so many parts per million, e.g. ± 1 part in 106 would mean […]
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Oscillators An oscillator is an electronic circuit designed to produce an alternat­ing e.m.f. of known frequency and waveform. In this chapter only oscillator circuits which produce an output voltage of sinusoidal waveform will be discussed. An oscillator is an amplifier that provides its own input signal, which is derived from the output signal (Fig. 1). […]
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Multi-stage Amplifiers Very often the voltage gain that an amplifier is required to provide is greater than can be supplied by a single stage. It is then necessary to connect two, or more, stages in cascade to obtain the required gain The term ‘cascade’ means that the output terminals of one stage are connected to […]
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Design of a single-state Audio-frequency Amplifer In the design of a single-stage audio-frequency amplifier a number of factors must be taken into account. These include the choice of operating point and the required voltage gain. Other factors such as the required bandwidth and the noise performance are also of importance but are beyond the scope […]
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Equivalent Circuits The voltage gain of a transistor amplifier can be calculated using an equivalent circuit, or model, of the transistor. An equivalent circuit is one that behaves in exactly the same way as the device it represents. Two equivalent circuits are often employed for audio-frequency amplifier calculations; these are the h parameter circuit and […]
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Determination of Gain using a Load Line The voltage gain of a FET amplifier or the current gain of a bipolar transistor amplifier can be determined with the aid of a load line drawn on the output current-output voltage characteristics of the device. The currents and voltages existing in the collector or drain circuit of […]
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FET Bias The drain characteristics shown in Fig. 13 show that a JFET is conducting when the gate-source voltage VGS is zero. The simplest method of biasing an n-channel JFET is therefore that given in Fig. 12. The disadvantages are (a) the maximum input signal amplitude must be very small if excessive distortion is to […]
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Bais and Stablization To establish the chosen operating point is necessary to apply a bias voltage or current to a FET or transistor. Transistor Bias If the current flowing into the base of a common-base-connected transistor is reduced to zero, only the collector leakage current still flows. When there is an input current the d.c. […]
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Small-signal Audio ­frequency Amplifiers An amplifier is a circuit that has two input terminals and two output terminals as shown by Fig. 1(a). Very often one input terminal and one output terminal are common, see Fig. 6.1(b). The action of the circuit is to increase the amplitude of, or amplify, the signal applied to the […]
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Shift Register A shift register is a digital circuit which can be used as a temporary store of data. It can be made using either J—K or D flip-flops as shown by Figs .16(a) and (b). Data to be stored in a register is applied one bit at a time (or serially) to the data […]
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