Function Generators, Wave Shaping Circuits | Analog Circuits - Electronics and Communication Engineering (ECE) PDF Download

Function Generators

• A Function Generator generates different voltage signals, such as Sine, Pulse, Triangle.
• The most commonly required signals in electronic circuits are Sine and Pulse.
• Sine wave signals find their use mostly in Analog circuits, such as amplifiers, filters, etc.
• Pulse signals are useful in testing the time response of circuits and also as Clock signals in Digital circuits.
• In a general pulse signal, the high and low level time periods are different. Square wave is a special case when the periods are equal.

Wave Shaping Circuits

Timing circuits networks composed of resistors, capacitors and inductors are called linear network and they do not change the waveform of a sine wave when it is transmitted through them. On the other hand when non-sinusoidal waveforms, (e.g. step, ramp, exponential) are applied to the input of such networks the output signal may have very little resembles with the input waveform. The action of a linear network in producing a waveform at its output different from its input is called linear wave shaping.

• Shaping circuits may be either series RC or series RL circuits.
• The series RC and RL circuits electrically perform the mathematical operation of integration and differentiation.
• Therefore, the circuits used to perform these operations are called integrators and differentiator.
• The differentiator circuits are used to generate sharp narrow pulses either from distorted pulse waveform or from rectangular wave forms.
• The integrator circuits are required to generate a voltage, which are required to generate a voltage, which increases or decreases linearly with time.

The wave shaping is used to perform any one of the following functions:

• To hold the waveform to a particular d.c. level.
• To generate one wave form the other.
• To limit the voltage level of the waveform of some presenting value and suppressing all other voltage levels in excess of the present level.
• To cut-off the positive and negative portions of the input waveform.

Non-sinusoidal Waveforms

Any waveform whose shape is different from that of sinusoidal wave is called a non-sinusoidal waveform.

1. Step Function: A step function shown makes an instantaneous jump from one steady value to another steady value. A step means an instantaneous change in level.
2. Ramp Function: A ramp function is one that voltage increases or decreases linearly with time.
3. Exponential Function: An exponential function is a function of voltage that increases or decreases exponentially with time.