I am tasked with designing a multistage amplifier (maximum 3 stages) for a course project. The project asks us to amplify a sinusoidal signal with an amplitude of 20mV and a frequency of 20kHz. The aim is to achieve maximum symmetry of the signal and to achieve the highest possible gain. Input-output phase is not of consideration. The topology may be DC or AC coupled. Vcc is +12V. Only CE and CC amps are allowed.
I have designed a common-emitter amplifier that has a gain of approximately -200 and I am happy with the gain. However, I observe significant clipping on the negative cycle of the output signal.
I know from my courses that to achieve maximum symmetrical swing, the Vc and Vce voltages should be at a certain level. However, what I want to achieve is to reduce the difference between the positive peak and the negative peak voltages at the output (relative to "center" of the signal). I know that in order to achieve this, I need to make my input signal smaller than 26mV. I have experimented by changing the input voltage to 10mV but I still observed significant asymmetry in terms of positive and negative peaks.
To lower my input signal, do you think that using a common-collector amplifier as first stage is viable? I know that the gain of a common-collector amplifier (at best) is unity and in practical terms is lower than unity, thus it attenuates the input signal to a degree. I am thinking of designing a common-collector amplifier with a NPN BJT as the first stage with a gain of apprixmately 0.1 so that the input signal will be attenuated to around 1-2mV.
Regarding that I need to create this circuit in lab environment, do you think a common-collector as first stage is viable or should I lower the input voltage by simply using a basic voltage divider?
If utilizing a common-collector for this purpose is a good idea, what would be the shortcomings? If its a bad idea, why?