How to make sure the 2-stage opamp is stable? How does the compensation work?
Mixed Signal Interview Questions
278 mixed signal interview questions shared by candidates
In what case miller compensation does not work?
They only ask one technical question about the NMOS transistor: 4V at gate, 5V at drain, open source, then what's the voltage at source.
1) Given an NMOS, 5V on Drain, 4V on Gate, what is voltage on source? 2) What happens when using a NMOS to pull up and/or a PMOS to pull down? 3) Given a rotating disk that's 1/4 black and 3/4 white, assume you have two sensors 90 degrees apart. How can you determine the direction the disk is rotating (clockwise vs counterclockwise) with some cmos circuit?
How would you draw the CMOS schematic for a 2-input NAND gate? What would the pull-up and pull-down networks look like? If VDD and VSS are switched, what gate is formed?
Perl Basics, Statistics, Analog Basics, RC circuits
Its an ADC Testing Day - Every interview was like go in to the room , they asked me to go to the board , and started questioning. But it was nice experience , it was question to answer interviews. 1)Draw Frequency Spectrum of output of an ADC , when the ADC is undersampled . Say f(in) = 10 MHz and Fs= 7 MHz. 2)Square wave in frequency domain will have odd or even harmonics ? 3) Every interviewer asked about how to test the static and dymanic parameters of an ADC, like DNL,SNDR, SNR (ideal). , Histogram Techniques , Coherent Sampling , Windowing, Ramp input vs Sine wave input testing 4)Basics on dB,dBm andfind rms power output. Given an input signal. 5)RC filter output wave amp and phase vs freq plots., transfer function of high pass filter 6)Some C programming questions. - String reversal, sorting, find max number, find prime number. 7)Some questions based on resume. ( projects ,very few) 8)Testing a DAC 9)Transmission Line - Impedence matching questions. Director asked me one question on how would I like to see myself in 5 years from now.
How would you size the NMOS and PMOS transistors in an inverter to obtain equal rise and fall times?
These are my onsite interview questions and some of them is related to my resume. 1. Given a chain of inverter, size the gates and calculate the delay; 2. Given an optimization goal, resize the chain of inverter, and recalculate the delay; 3. Given a typical 6T-SRAM, described how read and write work. Suppose we only have on access transistor but need to realize the read and write, how do you design the another access transistor? Both in analog and digital ways; 4. Given a simple charge pump circuit, figure out the waveform at certain nodes; 5. Given a ideal op-amp and 2 resistors with same value, draw the circuit gain of -1, 1 and 0.5, and in the third case, make sure that the input resistance is infinity; 6. Given a 50%-duty cycle waveform, draw the 33%-duty cycle waveform (division by 3), and draw the FSM state diagram to realize the division by 3; 7. Given a transmission line and a source with an adjustable resistance. If the load resistance of the transmission line is given, figure out the source resistance to make sure that the load has the maximum load power. If the transmission line is open on one end and connect an ideal current source at the other end, draw the voltage waveform at the output of the current source; 8. Given a rc high-pass filter and apply an input voltage step and take the output voltage from resistor, draw the voltage waveform of the resistor, and explain the waveform about its peak and rc time constant; 9. Given a self-bias amplifier with two logic inputs and one output, figure out the logic functions; 10. If the channel length of a device is cut down by 1/2, how does the unity-gain frequency change? Hint: Long and short channel devices are different; 10. Given a cs-amplifier with source degeneration (the classical continuous-time linear equalizer circuit), solve for the transfer functions, given the relative time constant positions, draw the bode plots, mainly about phase, explain why phase is positive and if this is contradictory to causality; 11. Given a 2-input nor gate, size the gate with equal rise and fall time, find out the faster input and explain why; 12. In high speed IO, why are the both Tx and Rx termination resistors matched with the characteristic impedance of the transmission line? 13. Describe your favorite project on your resume; 14. Draw the schematic of a PMOS, given the voltages of 4 terminals, and figure out the operation region of PMOS. Figure out the the output voltage of a cascaded PMOS circuit; 15. A transistor with its source connected a capacitor, apply a DC voltage at the drain, and figure out the voltage waveform of the capacitor; If you aced most of the technical questions, you are very likely to invited to be shown around the company, and then you will have the behavioral interview: 1. Tell me about yourself, like your past experience in middle school. 2. Tell me what you like about Analog Bits (usually after showing around the company). 3. What's your expectation of salary? 4. What's your hobbies? 5. Do you like your school and why? 6. When can you start? 7. If Analog Bits gives you an offer today and you get another offer from Broadcom and Qualcomm tomorrow, which one do you choose? 8. What do you see yourself in your career? 9. Give me two references.
Give you a disk, 1/4 of the pie is painted black, 3/4 is white. Two detectors which can detect the color (say, when black it output 1, white 0) are 90 degree with each other. Which kind of circuit can be used to detect whether the disk is rotating clockwise or counterclockwise?
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