Hello
Ive been given the following assignment problem
PROBLEM
A microphone has a peak open circuit voltage of 50mV with an output resistance of
15kΩ. Design an amplifier to allow this microphone to drive an 8Ω speaker in such a
way that the magnitude of the gain bandwidth product is maximised. The gain
bandwidth product is determined as
The following constraints are placed on your design.
1. The circuit is to be biased from a +10 / -10V DC power supply.
2. The circuit should produce no clipping or distortion in the output voltage
waveform when the input voltage is at its maximum value (50mVpk).
3. You can only use three transistors (and should use all three transistors). You have
available the following types of transistors: NPN transistor 2N3904 and a PNP
transistor 2N3906.
The first problem i had was what exactly should the gain be, i basically decided to choose an output of 5v peak based on a reasonble audio signal, giving a needed gain of 100. Given the largge input and small output impedence requirements, i went with a CC-CE-CC amp setup. This is where i run into problems, ive drawn the circut, managed to calculate some values (which i found very confusing and there is very little in the way of this when it comes to most of the recources i find, any links/info would be mucho appreciated) and simulated it in LTspice (the amp does not need to be built or have any power amp stages, just simulated) and nothing works, ive been at it for god knows how long and im just not getting anywhere on why its not working
Circuit i made:
http://img689.imageshack.us/i/invertingsinglece2.png/
Also i am completley lost as to how to actually choose good values for the capacitors, the ones there are basically just ones i pulled out of the air with no real backround
Anyhelp would be very much appreciated, this assignments worth quite a bit of my course and im getting very depressed at not having anything decent .
Thankyou.
Ive been given the following assignment problem
PROBLEM
A microphone has a peak open circuit voltage of 50mV with an output resistance of
15kΩ. Design an amplifier to allow this microphone to drive an 8Ω speaker in such a
way that the magnitude of the gain bandwidth product is maximised. The gain
bandwidth product is determined as
The following constraints are placed on your design.
1. The circuit is to be biased from a +10 / -10V DC power supply.
2. The circuit should produce no clipping or distortion in the output voltage
waveform when the input voltage is at its maximum value (50mVpk).
3. You can only use three transistors (and should use all three transistors). You have
available the following types of transistors: NPN transistor 2N3904 and a PNP
transistor 2N3906.
The first problem i had was what exactly should the gain be, i basically decided to choose an output of 5v peak based on a reasonble audio signal, giving a needed gain of 100. Given the largge input and small output impedence requirements, i went with a CC-CE-CC amp setup. This is where i run into problems, ive drawn the circut, managed to calculate some values (which i found very confusing and there is very little in the way of this when it comes to most of the recources i find, any links/info would be mucho appreciated) and simulated it in LTspice (the amp does not need to be built or have any power amp stages, just simulated) and nothing works, ive been at it for god knows how long and im just not getting anywhere on why its not working
Circuit i made:
http://img689.imageshack.us/i/invertingsinglece2.png/
Also i am completley lost as to how to actually choose good values for the capacitors, the ones there are basically just ones i pulled out of the air with no real backround
Anyhelp would be very much appreciated, this assignments worth quite a bit of my course and im getting very depressed at not having anything decent .
Thankyou.