Preparing for Integrated Circuit (IC) Design Technical Interviews

Song Liu is a Technical and Product Line Director at Monolithic Power Systems in San Jose, California. With extensive experience in analog and mixed-signal IC design, he brings real-world industry expertise to guide readers through the circuit intuition skills that distinguish successful candidates in technical interviews and enable effective transitions into professional circuit design roles.

• Preface 3Chapter 1 Impedance 7Question 1 Input and output resistance of a transimpedance amplifier (TIA) 13Question 2 Input capacitance of a source follower 17Question 3 Input capacitance of a differential pair 21Question 4 Output resistance of a tied-gate current source 23Question 5 Folded cascode amplifier and input Miller effect reduction 28Question 6 Impedance of a cross-coupled load 30Chapter 2 Amplifiers – Open-Loop and Closed-Loop 34Question 7 Stability of an uncompensated two-stage op-amp 35Question 8 Compensation for a two-stage op-amp, pole splitting 38Question 9 Nyquist stability criterion and conditional stability 43Question 10 Device noise contribution in a folded cascode amplifier 49Question 11 Slew rate limitations of a two-stage op-amp 56Question 12 Distortion in a common-source amplifier due to device nonlinearity 60Question 13 Common-emitter amplifier (BJT) with emitter degeneration 63Question 14 Amplifier input common-mode range and distortion 66Question 15 Common mode feedback control (CMFB) in fully differential amplifiers 69Question 16 Frequency response of two op-amp based low-pass filters 74Question 17 Feedback factors of inverting amplifiers and unity-gain buffers 78Question 18 Power supply rejection ratio (PSRR) of a voltage regulator 83Question 19 Power optimization of multistage open-loop amplifiers 89Question 20 Frequency response of a source follower 93Chapter 3 Bias and References 98Question 21 Designing a precision current mirror 99Question 22 Degeneration in current mirrors 103Question 23 Impact of resistance in current mirrors 106Question 24 Bandgap reference basics 111Question 25 Stability of beta-multiplier references 115Chapter 4 Switched-Capacitor Circuits and Comparators 120Question 26 Input impedance and kickback noise of switched-capacitor circuits 121Question 27 Sizing the switch for better linearity and less charge injection 126Question 28 Bottom plate sampling and signal-dependent charge injection 131Question 29 Requirements of the amplifier in a charge-transfer track/hold circuit 134Question 30 Impact of the amplifier input capacitance in switched-capacitor circuits 140Question 31 Thermal noise in switched-capacitor circuits 143Question 32 Switched-capacitor common-mode feedback (CMFB) circuits 148Question 33 Comparator – regenerative latch 152Question 34 Comparator – preamplifier 158Question 35 Comparator – offset cancellation (IOS) 162Question 36 Switched-inductor circuits – buck converters 167Chapter 5 Digital Circuits from an Analog Perspective 174Question 37 Inverter-based ring oscillators 175Question 38 Inverter optimization of propagation delay and duty cycle distortion 177Question 39 Designing buffers for driving long RC lines 181Question 40 Inverter switching current and power consumption 184Question 41 Master/slave D flip-flops and setup/hold time 188Question 42 Clock divider with D flip-flops 192Question 43 Digital phase-frequency detectors and phase-locked loops (PLLs) 195Question 44 Metastability in digital systems 202Chapter 6 Circuit Layout Techniques 206Question 45 Transistor layout for parasitic reduction 207Question 46 Interdigitation for matching 210Question 47 Layout of decoupling capacitors 213Question 48 Substrate/well contact and latch-up 215Question 49 Shielding in layout – grounded or not grounded? Which ground? 219Question 50 Optimizing the padframe for power and ground 225Appendix 1 Device Equations 231Section 1 MOSFET (long-channel) equations 231Section 2 Bipolar transistor (BJT) equations 234Section 3 Diode (PN junction) equations 238Section 4 Resistor, capacitor and inductor equations 239Appendix 2 Circuit Theorems 240Section 1 Kirchhoff's circuit laws 240Section 2 Thévenin's theorem and Norton's theorem 242Section 3 The superposition theorem 244Section 4 Miller theorem 245Appendix 3 Circuit Analysis in the Complex Frequency Domain (s-domain) 246Section 1 Laplace transform and transfer functions 246Section 2 First-order systems 250Section 3 Transfer function of feedback systems 252Section 4 Second-order systems 254Section 5 S-domain and frequency domain 258Appendix 4 Basic Circuit Analysis Examples 261Section 1 Voltage and current dividers 261Section 2 RC circuits – transient and frequency response 265Section 3 Basic amplifiers 270Section 4 Basic op-amp based closed-loop circuits 278Section 5 Types of negative feedback in amplifier circuits 283Section 6 Circuit noise fundamentals 288Section 7 Basic digital circuits 297