Circuit design engineer Interview Questions

84

Circuit Design Engineer interview questions shared by candidates

Top Interview Questions

Sort: Relevance|Popular|Date
Dolphin Technology
Circuit Design Engineer was asked...26 May 2016

Basic MOSFET, CMOS questions were asked.

11 Answers

Hey, you should feel glad that you weren't accepted by them. This company is very cheap and doesn't treat its employees well. Less

I guess...but it is not the right way to interview candidates don't you think?

That's really sad. They should rather go with Skype or any other means to interview. Now,. I have got an on-site call for Digital circuit design and I am giving it a serious thought 🤔 Less

Show More Responses
Dolphin Technology

How Sense Amplifier works.

3 Answers

Cool question!

Very cool question

I am not from Analog background but my analytical ability lead me through to answer it perfectly. Less

Analog Bits

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.

3 Answers

Source will be at 4V-Vt.

bcz the source is open current Ids is zero, so the transistor is in cutoff region and hence Vgs =0, therefore Vg = Vs Less

if vdvg, source voltage is about (not exatly since it depends on the bulk connection) a voltge between vd and vg (it depends on how far they are from each other because the current value will be different) Less

Analog Bits

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?

3 Answers

Buffer

AND. When VDD and VSS are reversed, the NMOSs connected in series becomes the PUN, and parallel PMOSs become the PDN. As long as either of the input is 0, the PDN will conduct, pulling the output to 0. It is only when both inputs are 1 will the PUN conduct, pulling the output to 1. Less

NOR gate

Analog Bits

They asked things like if the source of NMOS is open, what is the voltage at the source if the gate and drain at 3 and 5V. If the gate of inverter is connected through a resistor to a output, what is the output voltage? Also things related to ring oscillator. Mostly just digital stuff, nothing analog like others have said.

2 Answers

The output will be a constant value Vdd/2. As the resistor will force two nodes to be the same since no current flow though. Less

Since there won't be any dc current if the source is open, the source will be at Vg-Vth i.e. 3-vth Less

Analog Bits

How would you size the NMOS and PMOS transistors in an inverter to obtain equal rise and fall times?

2 Answers

pmos size has to more than twice than nmos. thats how you get equal rise and fall time. Less

Depends on the mobility ratio

Analog Bits

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.

2 Answers

These questions are really basic, please answer them by yourself!

How was the On Site interview Scheduled? Did you do technical interview first and then behaviorial? How long overall did the on site interview last? Thanks Less

Analog Bits

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?

2 Answers

Use flip-flop. output of one detector as clock, the other as din.

A tristate PFD

Dolphin Technology

C questions sheet ( 5 questions including questions on binary tree, difference between ++var and var++, sorting question)

1 Answers

Could you give more detail about the C programming questions? Thank you!

Dolphin Technology

MOSFET Ids equations

1 Answers

need to give the equations

Viewing 1 - 10 of 84 Interview Questions