Please give some explaination for there questions. 1. Which capacitor internal t
ID: 2249803 • Letter: P
Question
Please give some explaination for there questions.
1. Which capacitor internal to the transistor limits the high-frequency cutoff frequency of the common emitter (CE) or common source (CS) amplifier? Explain why.
2. One can achieve high voltage gain with CE/CS amplifier but with low cutoff frequency. How could you improve this situation to achieve *both* acceptable cutoff and high gain?
3. For an op-amp circuit, assuming non-inverting/inverting amplifier, how do we determine if there is a risk of instability by looking at the open loop frequency response of the op-amp?
4. For a differential pair biased with a common current source in the emitter/source of the transistors, what limits the maximum/minimum common mode input to the differential pair? Does this change if the bias to differential pair consists of resistor in the common emitter/source node of the differential pair instead of a current source? Explain why/why not.
Explanation / Answer
Stray capacitance is needed in ce or cs amplifier to reduce the noise stability and due to this the upper limit operation for an amplifier is effected and the function of capacitor is to provide dc isolation from voltages to the next circuitand because of that there is a effect on bandwidth
2.due to increse in amplifier gain there will be decrease in bandwidth and due to this some part of the input signal is eliminatedamd die to high gain amplifier introduces some dc offset and in high input impedance increasing the gain leads to dc offset which leads to the effect on operating point
3.the capacitive input makes it very susceptible to random noise signals and the noise or harmonics present in it are ampilfied more than the input signal.this is because of the output proprtional to the input voltage.so limiting the bandwidth in order to achieve closed loop stability is required
4.the collector resistors can be replaced by a current mirror and the collector signal is converted to a single ended voltage signal without the intinsic 50% losses and the gain is extremely increased