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MICROWIND & DSCH V3.5 - LITE USER'S MANUAL
9.Radio-frequency Circuits
Figure 10-8 : The class A amplifier has a sinusoidal input (PowerAmplifierClassA.MSK)
The sinusoidal input offset is 0.7 V, the amplitude is 0.4V. The power MOS functional point
trajectory is plotted in figure 9-8, and is obtained using the command Simulate on Layout. We
see the evolution of the functional point with the voltage parameters: as Vgs varies from 0.3 V
to 1.1 V, Ids fluctuates between 10 mA and 30 mA. The MOS device is always conducting,
which corresponds to class A amplifiers.
Oscillator
The role of oscillators is to create a periodic logic or analog signal with a stable and predictable
frequency. Oscillators are required to generate the carrying signals for radio frequency
transmission, but also for the main clocks of processors. The ring oscillator is a very simple
oscillator circuit, based on the switching delay existing between the input and output of an
inverter. If we connect an odd chain of inverters, we obtain a natural oscillation, with a period
which corresponds roughly to the number of elementary delays per gate. The fastest oscillation
is obtained with 3 inverters (One single inverter connected to itself does not oscillate). The
usual implementation consists in a series of five up to one hundred chained inverters (Figure 99).
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21/09/2009