Part -1:
The written submission should be in the form of a report, with standard referencing, that covers questions 1-5 below
The questions should be read in conjunction with the original laboratory script 1 for the Amplifiers experiment.
1. Redesign the amplifier of Figure 1 such that the DC bias conditions are identical to the original circuit (this means the same collector and emitter voltages and currents), but the AC voltage gain is 5.
2. The original specification for the amplifier asked for a gain of 10, but in the practical implementation it usually comes out slightly less than 10. Why is this, and how accurate would you expect the actual circuit gain to be for the new value of 5?
3. What defines the high frequency bandwidth (upper 3dB point) of the amplifier and how would it change, if at all, if the gain is reduced from 10 to 5?
4. Figure 4 of the labscript gives an outline design for a two-stage direct coupled amplifier in which both stages have series negative feedback. Assuming the first stage (T1) has identical component values to those of Question 1, calculate suitable values for RE2, RF2 and RC2.
5. Find the approximate dynamic range of the output signal from your design for Figure
4. (This is the maximum output signal voltage that can be obtained without 'clipping' on its high and low levels.)
Part -2:
The written submission should be in the form of a report, with standard referencing, that covers questions 1-5 below.
The questions should be read in conjunction with the original laboratory script 2 for the Oscillators experiment.
The Oscillators laboratory experiment was based on the Wien Bridge oscillator design, which uses a lead-lag CR network: at one frequency, the phase shift through the circuit is zero and its 'gain' is
a maximum. In this design the CR network introduces a phase shift of 180 degrees at the oscillation frequency.
1. What defines the maximum output signal amplitude of the two oscillator types, lead- lag, and phase shift, and what is the effect, if any, on the spectral purity of the output signal? (The ideal output waveform would be a pure sinewave; any distortion generates harmonic components as well.)
2. Where on both circuits should the output signal be taken to ensure the minimum level of harmonic distortion?
3. Section 5 of the Oscillators laboratory script introduces amplitude stabilisation. What is the effect, if any, on harmonic distortion of the output signal?
4. Suggest an amplitude feedback control method that could be used to stabilise the output signal from the phase shift oscillator.
5. Discuss the behaviour of the Wien Bridge oscillator if the gain of the op amp circuit is made slightly less than the 3 required for oscillation, and a low amplitude external sinewave is injected into amplifier summing node (i.e. the inverting input of the op amp) via a suitable resistor. (This is Experiment 10 in the labscript.)
Attachment:- Lab Script.rar