Methods of Sweep Voltage Generation:
It is not possible to achieve precise linearity in sweep voltages by electronic means, various methods of sweep voltage generation are enumerated below.
1. Exponential Charging: In this method of time-base waveform generation, a capacitor is charged exponentially through a resistor from a constant voltage source to a voltage quite small as compared to the source voltage.
2. Constant Current Charging: In this methods of sweep voltage generation, a capacitor is charged linearly from a constant current source.
3. Miller Circuit: In this circuit an operational integrator is used for converting a step into a ramp waveform.
4. Phantastron Circuit: It is a version of the Miller circuit that needs a pulse input instead of an external step or gating signal waveform.
5. Bootstrap Circuit: In this circuit, a constant current is approximated by maintaining a constant voltage across a series combination of a resistor and a capacitor.
6. Compensating Network: This circuit is required to be used in conjunction with bootstrap and Miller time base generators so as to improve linearity.
7. Inductor Circuit: An R-L-C series circuit is used to yield more linear charging of capacitor than that can be achieved by only an RC circuit.
All the above circuits may make use of vacuum tubes, gas tubes, transistors or other semiconductor devices depending upon convenience, speed, application and other practical considerÂations.