This course is intended to develop understanding of why power management circuits are needed in a VLSI system, what are the different components of a power management system with focus on voltage regulators. By the end of this course, students should be able to understand the concept behind power management circuits and design a linear (LDO) and switching regulator (dc-dc converter) for a given specifications using behavioral and circuit level simulators.
INTENDED AUDIENCE : Final year undergraduate, graduate, PhD students in Electrical/Electronic Engineering. Faculty teaching or intended to teach course on analog IC design and/or power management IC Industry professionals working in the area of analog IC design, VLSI, power management ICs.
PREREQUISITES : Analog Circuits or equivalent or industry experience in analog circuit design
INDUSTRY SUPPORT : Qualcomm, Texas Instruments, Intel, Sankalp Semiconductor, NXP Semiconductors, ST Microelectronics, Samsung, Microchip, ON semiconductor, Infineon, Renesas, Analog Devices
Week 1 : Introduction to power management, application, need, discrete vs. integrated PMIC, dc-dc converter, types of dc-dc converter, linear vs switching regulator, Linear vs switching regulator, selecting between linear and switching regulators, power management of a smartphone, performance parameters-efficiency, accuracy, line and load regulation, line transient, load transient, PSRR, remote vs. local feedback, point-of-load, kelvin sensing, droop compensation.
Week 2 : Bandgap voltage reference, PTAT and CTAT voltage reference, designing a bandgap reference using PTAT and CTAT, Brokaw bandgap reference, Sub-1V bandgap reference, introduction of linear regulator, pass elements, review of feedback system and bode plot, loop gain AC analysis, stability criterion and phase margin.
Week 3 : Review of 2nd order system, relationship between damping factor and phase margin, stabilizing a linear regulator - compensation techniques, dominant pole compensation, miller compensation, R.H.P. zero in miller compensation, determining poles and zeroes after miller compensation, pole splitting, reducing the effect of R.H.P.
Week 4 : Load regulation and output impedance of LDO), line regulation and power supply rejection of LDO, NMOS LDO, sources of error in regulator, static offset correction, Dynamic offset cancellation, digital LDO, hybrid LDO, current limit and short circuit protection.
Week 5 : Basic concept of switching regulator, inductor ripple current, volt-second balance, power stage and calculating duty cycle resistive losses, transformer model of a buck converter, efficiency of switching regulator, efficiency with only conduction losses, synchronous and non-synchronous converter, losses in switching dc-dc converter- conduction loss, gate switching loss, dead time switching loss, hard switching loss, magnetic loss, power loss vs. load current.
Week 6 : Output voltage ripple in dc-dc converter, ripple voltage vs. duty cycle, ripple voltage vs input supply voltage, choosing inductor and capacitor, continuous and dis-continuous conduction modes, pulse width modulation - trailing, leading and dual edge modulation, voltage mode control, small signal modelling of dc-dc converter, loop gain analysis using continuous time model.
Week 7 : Compensating a voltage mode buck converter, type-I(integral) compensation, designing type-II (PI), type-III (PID) compensator, finding compensation parameters, designing type-III compensator using op-amp-RC and gm-C, design examples.
Week 8 : Current mode control, types of current mode control – peak, valley and average current control, sub-harmonic oscillations, slope compensation, small signal model and compensation of current mode controlled buck converter.
Week 9 : Hysteretic control, stability issues with hysteretic control, voltage vs. current mode hysteretic control, effect of loop delay in hysteretic control, fixed frequency hysteretic control, constant-ON time control, adaptive ON time control, basic concept of boost converter, switched capacitor dc-dc converters.
Week 10 : Selecting buck topology, switching frequency and external components, sizing power FETs, segmented power FET, designing gate driver, PWM modulator, error amplifier, oscillator, ramp generator, ramp generator with feed-forward compensation, feedback resistors, current sensing, PFM/PSM mode for light load, effect of parasitic on reliability and performance, current limit and short circuit protection, soft start control.
Week 11 : Choosing type of regulator in multi-chip system, selecting process node for PMIC, chip level layout and placement guidelines, board level layout guidelines, EMI considerations, system level techniques for efficiency improvement.
Week 12 : Introduction to advanced topics in PMIC:Digitally controlled dc-dc converters, time-based control for voltage regulators, adaptive compensation, dynamic voltage scaling (DVS), Single-Inductor Multiple-Outputs (SIMO) Converters, dc-dc converters for LED lighting, Li-ion battery charger.