# (HELP)Passive filter and BJt amplifier Project

Discussion in 'Homework Help' started by walou, Aug 26, 2010.

1. ### walou Thread Starter New Member

Aug 26, 2010
2
0
Purpose :

your task will be to design an amplifier and low pass filter (LPF) circuit

Problem statement :
you were tasked to design the amplifier and filter circuit for the radio sets.... benchmarking will be done with this specifications :

Specification
Input waveform : 1v peak to peak sine wave
LPF cutoff frequency : 2khz

Input frequency : 100hz : 1khz : 2khz : 20khz : 200khz
output amplitude : 10 vp-p : <10 vp-p :5vp-p : <=1 vp-p : <=0.1vp-p

tips :
is is suggested that you use a comjbination passive filter and BJYT amplifier (inverting ) circuit

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i dont have any guide to solve this project + with my knowledge of electronic ~~!!! so aWesome,just start to learn

if you all have any suggestion or diagram plss post and help me ....
thanks

2. ### Flow Member

May 30, 2010
37
1
Have you not had any theory on BJT transistors and systems theory before? Cuz that's a bit rough a project without knowledge.

1) A low-pass filter with -20dB per decade. That's a simple first-order filter.
2) A simple BJT invertig amplifier stage with a gain of 10.
3) Connecting the two together. You'll want to match the output impedance of the filter to the input impedance of the amplifier. The two systems will affect each other.

Btw, is that 5V peak to peak voltage at the cutoff frequency fixed? Because the cutoff frequency is usually defined at -3db, or at 1/sqrt(2) times the reference, which would here be around 7.07V, given the maximum output voltage of 10V.

walou likes this.
3. ### walou Thread Starter New Member

Aug 26, 2010
2
0
flow i can say that my knowledge regarding electronic (basic) is zero
do u have any idea or things that i should learn