MAHATMA GANDHI INSTITUTE OF TECHNICAL EDUCATION & RESEARCH CENTER SUBJECT NAME: Analog Electronics ENROLLMENT NO:

1. Frequency Multiplication 2. FSK Demodulator 3. FM demodulation 4. Three terminal regulator Ics: basic block schematic 5. 78XX & 79XX series

-PLLs can multiply the clock frequency Distribute a lower frequency on the board Multiply it up on-chip Possible to adjust the frequency on the fly

- -FSK is used in computer peripherals and radio wireless communication of binary data or codes. - -The carrier frequency is shifted to either fh or fl depending on whether a binary “1” or “0” is to be transmitted respectively. - -Thus if a “1” is to be sent,the transmitter will transmit a signal at frequency “fh” and if a “0” is to be sent then the transmitter frequency “fl”.

 What are Frequency demodulators ?  They produce output voltage whose instantaneous amplitude is directly proportional to the instantaneous frequency of the input FM wave.  Methods: 1.Frequency Discriminator followed by an envelope detector.  Slope Circuit  signal differentiation method 2.Phase locked loop demodulator. 3.Zero-crossing detector. 4.Ratio-detector. (old)

 First, transfer the information from the angle to the magnitude  For example: derivate of a sinusoid results in multiplying the magnitude of the sinusoid by the derivate of its angle, the derivative of the above FM signal becomes form Is this signal amplitude or frequency modulated?

 Because the information is also contained in the amplitude we can use AM demodulation Envelope detector can be used because The message is always represented by the positive term of the envelope.

The same idea can be used for PM demodulation. A PM signal has the form If this signal is passed through an envelope detector, the output will be proportional to the derivative of the message signal. An integrator will solve the problem

 What if the amplitude A is not constant because of channel noise? i.e. A(t)  At the output of the differentiator, we will have other terms d/dt (A(t)) The use of bandpass limiter also suppresses the channel noise when the noise is small.

PLLs when fed with an FM signal directly produce an output signal that is proportional to the message signal. PLL has low cost and superior performance even at low SNR (signal-to-noise ratio) Where do we take the output? Compare with the case of carrier acquisition.

 -The discrete component regulators circuits such as the zener voltage regulators are not much used in practice. -Now adays the voltage regulators circuits are available in the integrated circuit form and the IC regulators are widely used.

1. The power supply design becomes easy and quick. 2. The IC regulators are cheap and are easily available. 3. IC regulators are small hence they reduce the size of the power supply. 4. They are easy to use. 5. IC regulators are versatile.

The three terminal IC voltage regulators are classified in to foliowing categories: 1. Fixed voltage regulators 2. Adjustable output voltage regulators

 Both the 78XX and 79XX regulators can be used to provide +ve or -ve output voltages  C 1 and C 2 are generally optional. C 1 is used to cancel any inductance present, and C 2 improves the transient response. If used, they should preferably be either 1  F tantalum type or 0.1  F mica type capacitors.