Electronic circuits II Example set of questions Łódź 2013

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Theodore Shields
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1 (V) (V) (V) (V) Electronic circuits II Example set of questions Łódź 213 1) Explain difference between the noise and the distortion. 2) Explain difference between the noise and the interference. 3) Explain why efficiency of a power amplifier is important? 4) Give the conditions that must be met in order to amplifier does not introduce linear distortions. 5) An amplifier Has gain of 6db. Express the gain in V/V. 6) Give difference between linear and nonlinear distortions. 7) The drawings below shows the waveforms and FFT of input and output signals of an amplifier. What kind of distortion was introduced by the amplifier. Justify the answer m 5.m 1.m 15.m 2.m 25.m 3.m Time (s) 5. vout m 5.m 1.m 15.m 2.m 25.m 3.m Time (s) vin 8.m 7.m 6.m 5.m 4.m 3.m 2.m 1.m FFT of "Transient Analysis" Chart, length = 128.m.k.5k 1.k 1.5k 2.k (Hz) vin vout..k.5k 1.k 1.5k 2.k (Hz) 8) Define PSRR (Power Supply Reejection Ratio). 9) Define CMRR (Common Mode Reejection Ratio). 1) Shortly characterize amplifier of class: A,B,C,D. 11) Shortly discuss principle of operations of class D amplifier(particularly mode of operation and type of load). 12) On the figure bellow an internal schematic of an power amplifier is show. Which class this amplifier belongs. Justify the answer. 13) List sources of power loss in output stage of D class amplifier. 14) Give the basic difference between operation of the output stage between 2AB class and D class power amplifier. 15) Define Dead Time. 16) List 6 causes of imperfection in Class D Power Amplifiers. 17) Which quality parameter depends on Dead Time in Class D Power Amplifiers. 18) Define a phenomenon of Power Supply Pumping in Class D Power Amplifiers. 19) What type of an output stage, in Class D Power Amplifiers, is affected by the phenomenon of Power Supply Pumping. 2) Why Gate Drivers are needed in Class D Power Amplifiers. 21) Shortly explain operation of the Boot Strap circuit in a Gate Driver circuit for half bridge output stage.

Electronic circuits II Example set of questions Łódź 213 22) On the figure bellow an internal schematic of an power amplifier is show. Which class this amplifier belongs. Justify the answer.

2 Electronic circuits II Example set of questions Łódź ) On the figure bellow an internal schematic of an power amplifier is show. Which class this amplifier belongs. Justify the answer. 23) Below one of power amplifier characteristics is show. Based on this characteristic give maximum output power if the amplifier will be used in Police car for the PA (public Audio) speaker.

Electronic circuits II Example set of questions Łódź 213 24) Below one of power amplifier characteristics is show.

3 Electronic circuits II Example set of questions Łódź ) Below one of power amplifier characteristics is show. Based on this characteristic give maximum power which can be dissipated in amplifier without heat sink if the ambient temperature will be 4 C 25) A part of power amplifier data sheet is shown characteristics is show below. Based on this part give the range of the output voltage swing. 26) Define rise time of the signal. 27) Explain relationship between rise time and high cutoff frequency of broadband amplifier. 28) To the input of the amplifier a test signal source is connected. Parameters of the amplifier are: gain = 6dB, bandwidth = -1MHz. Parameters of the test signal, wave shape rectangular, pulse width 75% off voltage V, on voltage 2,5mV. Sketch output signal of this amplifier if no nonlinear distortions are introduced

4 (V) Electronic circuits II Example set of questions Łódź ) List impulse response distortions shown in the time plot of amplifiers output voltage. Mark those distortions on the plot. 2,25 2, v_out v_in 1,75 1,5 1,25 1,,75,5,25, -,25,u 1,u 2,u 3,u 4,u 5,u 6,u 7,u 8,u Time (s) 3) What will happen to the impulse response of the high-pass amplifier when we increase the lower limit frequency? 31) In the figures below the frequency characteristics of the three amplifiers are show. Mark the characteristics of the amplifier with the shortest delay in the impulse response. 3, 25, vout_p1/vin_p1 vout_p2/vin_p2 vout_p3/vin_p3 2, 15, 1, 5,, 1, 1, 1,k 1,M 1,M Frequency (Hz)

V V Electronic circuits II Example set of questions Łódź 213 32) The figure below shows a transistor amplifier in CE (Common Emitter) configuration.

R4 2k Rc 5k C2 Rs C1 Q1 1uF VOFF = VAMPL = 1mV FREQ = 1kHz AC = 1mV Vs 5 1uF R3 18k Q2N2222 R5 {Par} RL 1k 33) The figure below shows the impulse response of two amplifiers built by means of the same

5 V V Electronic circuits II Example set of questions Łódź ) The figure below shows a transistor amplifier in CE (Common Emitter) configuration. How does the R5 value affects the bandwidth of the amplifier? R4 2k Rc 5k C2 Rs C1 Q1 1uF VOFF = VAMPL = 1mV FREQ = 1kHz AC = 1mV Vs 5 1uF R3 18k Q2N2222 R5 {Par} RL 1k 33) The figure below shows the impulse response of two amplifiers built by means of the same integrated circuit. Highlight a transient response of the faster amplifier. Explain the reason for the difference in speed of these two amplifiers. 34) The figures below shows the frequency characteristic of two amplifier ICs. Highlight a characteristic of the amplifier which should be applied for design an amplifier having shortest possible rise time. 35) Draw the amplitude characteristics of the NOTCH filter. 36) Draw the amplitude characteristics of the Comb filter. 37) Give difference between Butterworth and Czebyschew type 1 filter characteristic.

(Deg) (V) Electronic circuits II Example set of questions Łódź 213 38) Give difference between Butterworth and Bessel filter characteristic 39) What is the advantage of the filter of order 5 over the

6 (Deg) (V) Electronic circuits II Example set of questions Łódź ) Give difference between Butterworth and Bessel filter characteristic 39) What is the advantage of the filter of order 5 over the filter of order 1. 4) Draw a scheme the active low-pass filter. 41) For which signals the filter from the figure below can be regarded as a high-pass filter. 1,1 1,,9,8,7,6,5,4,3,2,1, -,1 1, 1, 1,k 1,M 1,M 1,G Frequency (Hz) 2, 125, 5, -25, -1, -175, -25, -325, -4, 1, 1, 1,k 1,M 1,M 1,G Frequency (Hz) vout/vin PHASE(vout/vin) 42) Explain the principle of operation of switched-capacitor resistor. 43) The figure below shows the frequency response of the digital filter. Give the minimum attenuation in the stop band. 44) The figure below shows tipical application schematic for LCT162 IC(Switched Capacitor Filter Explain the functions of the highlighted items. 45) The figure below shows selected characteristics of switched-capacitor filter (MAX28). How to choose the values of the resistance and capacitance of the input filter in order to have Butterworth type filter response

Electronic circuits II Example set of questions Łódź 213.

Based on this part give output voltage range. 47) Draw a schematic of Any multiplier circuit.

7 Electronic circuits II Example set of questions Łódź ) A part of power amplifier data sheet is shown characteristics is show below. Based on this part give output voltage range. 47) Draw a schematic of Any multiplier circuit. 48) Explain what it means that the multiplier circuit is a two quadrant one. 49) Briefly describe two ways of linearization of the two-quadrant multiplier circuit. 5) Describe the principle of operation of Gilbert type linearization circuit.

8 Electronic circuits II Example set of questions Łódź ) Explain the function performed by the resistors R3 and R4 in the schematic below. R1 R2 V3 Q1 1 Q2 V- V+ R3 21 R V2 G1 + - G GAIN = 1 52) Explain the principle of linearization used in the circuit of the figure below. R6 R3 R2 Q1 Q9 Q3 Q4 Q1 Q2 V3 1m Q7 I3 R5 1k 1m Q8 I4 V2 1m Q5 I1 R4 1k 1m Q6 I2 53) Draw the spectrum of the modulated signal for LSB modulation (single side band amplitude modulation lower band broadcast) if the carrier is 2MHz modulating signal is shown below. 25kH 125kH 54) Draw a schematic any demodulator AM. Briefly explain its principle of operation. 55) Why after passing the diode the AM signal contains harmonics. 56) Shortly describe super diode circuit. 57) Sketch the time plot of AM (DSB-LC) modulated signal if modulation signal is a rectangle shaped signal with fundamental frequency of 1kHz, carrier frequency is 1kHz modulation coefficient 5%. For a simplification

9 Electronic circuits II Example set of questions Łódź 213 represent carrier as saw (triangle) shaped signal. 58) Draw a block diagram of a PLL circuit for multiplication of the reference generator frequency. 59) Give the minimum sampling frequency for the signal with the spectrum shown below: 6) Draw a block diagram and briefly explain the operating principle of successive approximation SAR ADC. 61) Draw a block diagram and briefly explain the operating principle of direct comparison FLASH ADC 62) Draw a block diagram and briefly explain the operating principle of double integration ADC 63) Draw a block diagram and briefly explain the operating principle of (delta sigma) ADC 64) Write down series of output values of ADC in binary code. Signal on the input is shown below. Parameters of the converter are as follow: Voltage input range -4V, resolution 4 bits, sampling frequency 2 khz. Mark the quantized sample values on the graph. 4V 2us 4us 65) Define /Explain Integral Nonlinearity (INL) Error. 66) Define /Explain Differential Nonlinearity (DNL) Error. 67) Describe Oversampling 68) Describe Multiplying DAC. 69) Explain principles of Ratiometric Measurement.

10 Electronic circuits II Example set of questions Łódź 213 7) Shortly describe element pointed by arrow In the AD7714. What it is what is it its function. 71) The picture below shows the internal construction of the converter MAX14. What kind of converter constitutes this IC?

R (a) Explain characteristics and limitations of op-amp comparators. (b) Explain operation of free running Multivibrator using op-amp.

R (a) Explain characteristics and limitations of op-amp comparators. (b) Explain operation of free running Multivibrator using op-amp. Set No: 1 1. (a) Draw the equivalent circuits of emitter coupled differential amplifier from which calculate Ad. (b) Draw the block diagram of four stage cascaded amplifier. Explain the function of each