Monolithic Power Systems, Inc. · NASDAQ:MPWR
Monolithic Power Systems — Technical Presentation (March 2024)
25 slides from Monolithic Power Systems's technical presentation, Mar 5, 2024
Slide 1: MPS Axign Class-D Technology Deep-Dive
MPS Axign Class-D Technology Deep-Dive February 2024 Start Time: March 5, 2024 | 1:00 AM PST | 4:00 AM EST | 10:00 AM CET | 5:00 PM CST | 12:00 PM EAT
Slide 2: Table of Contents
Table of Contents • Introduction • Post-Filter Feedback in Class-D Audio • Low-Latency ADC (LLADC) • Configurable Digital Feedback Loop • ADC configuration • Digital Loop Filter configuration • Pulse-width Modulation • Summary & Conclusion
Slide 3: Introduction
Introduction • Axign is a fabless semiconductor company based in the Netherlands • Two locations in NL: • Enschede (HQ) • Nijmegen • Long relationship between Axign and MPS due to complementary IP • Axign acquired by MPS at the beginning of 2024 “Axign is excited to announce that we are now a part o
Slide 4: Post-Filter Feedback in Class-D Audio
Post-Filter Feedback in Class-D Audio Using MPS Axign Technology
Slide 5: Post-Filter Feedback in Class-D Audio
Post-Filter Feedback in Class-D Audio • What is class-D audio? • Switching audio amplifier • Modulator creates PWM/PDM • What is post-filter feedback (PFF) in Class-D audio? • PFF implies taking the feedback point after the output filter • Feedback suppresses noise and distortion in the forward path
Slide 6: Post-Filter Feedback in Class-D Audio
Post-Filter Feedback in Class-D Audio • In the analog domain, parameter spread will present a limitation • High-order designs will have smaller margins of stability • Digital feedback loops are consistent and programmable • Digital coefficients are loaded on start-up • Programmable feedback loops ca
Slide 7: Post-Filter Feedback in Class-D Audio
Post-Filter Feedback in Class-D Audio • 2-CH and 4-CH controllers for post-filter feedback available now • Power-stages and DC-DC available from MPS • AX5688 and AX5689 are power-stage agnostic • More MPS Axign products are in development
Slide 8: Post-Filter Feedback in Class-D Audio
Post-Filter Feedback in Class-D Audio • AX5689 Block diagram shows more detail • AX5689 contains • PWM x8 • Low-latency ADC x8 • Loop Filter x8 • DM and CM separated • Possibility for PWM feedback • Low-latency ADC has two inputs
Slide 9: Low-Latency ADC (LLADC)
Low-Latency ADC (LLADC) mrS
Slide 10: Low-Latency ADC (LLADC)
Low-Latency ADC (LLADC) • AX5688 contains 4x LLADC • AX5689 contains 8x LLADC • LLADCs in parallel gives higher performance
Slide 11: Low-Latency ADC (LLADC)
Low-Latency ADC (LLADC) • Differential input ADC • Optimized for bridge-tied load (BTL) operation • Larger signal swing with two signals in anti-phase • Differential design eliminates even-order distortion • DM and CM Split • Common-mode determined by average of input currents • Differential-mode de
Slide 12: Low-Latency ADC (LLADC)
Low-Latency ADC (LLADC) • Current input ADC • ADC resistors convert output voltage into ADC current • Scalable for all levels of PVDD • Usable with multiple different power stages • E.g. woofer/tweeter split • Woofer at high PVDD • Tweeter at low PVDD • Digital control system acts on digital ADC out
Slide 13: Configurable Digital Feedback Loop
Configurable Digital Feedback Loop Using the AX5688 and AX5689
Slide 14: Configurable Digital Feedback Loop – ADC configuration
Digital Feedback Configurable Digital LoopLoop – ADC configuration • Flexible ADC configuration to leverage all the hardware for a chosen topology • Configurable ADC options example: • 4x2 ADCs or 2x4 ADCs • 6 ADCs to tweeter & 2 ADCs to woofer • 3 dB boost to dynamic range for every doubling of par
Slide 15: Configurable Digital Loop – Loop filters
Configurable Digital Loop – Loop filters • 8 configurable Digital Loop Filter slices • Loop filter slices can be used to form several digital DM and CM feedback loops • Common-mode feedback loops damp the output filter resonance • Common-mode LC response is not damped by the differential load • Elim
Slide 16: Pulse Width Modulation
Pulse Width Modulation Using the AX5688 and AX5689
Slide 17: Pulse Width Modulation
Pulse Width Modulation • Class-D is traditionally popular due to its high efficiency • Typical audio content contains very low average power • Losses at normal listening levels are largely determined by: • Switching losses • Ripple losses • Switching losses largely occur due to the (parasitic) capac
Slide 18: Pulse Width Modulation - ZCM
Pulse Width Modulation - ZCM • Fix both switching losses and ripple losses with one solution: • Zero common-mode (ZCM) switching • Only one side switches, reducing switching losses drastically • Eliminates ripple currents for very small signals BD Modulation ZCM Modulation
Slide 19: Pulse Width Modulation - ZCM
Pulse Width Modulation - ZCM • Traditionally causes significant (crossover) distortion • Distortion in the audio band is eliminated by high loop gain • > 60 dB loop gain makes crossover distortion negligible • THD+N well below 0.005% is possible • Frequency independent • Load independent Combining e
Slide 20: PWM Configuration
PWM Configuration • 8 configurable PWM outputs • Flexible PWM configurations • 4x Bridge-tied load (BTL) • 2x Parallel BTL (PBTL) • 2x BTL + 1x PBTL • PBTL is typically chosen for higher output power • When using 4 PWM outputs, we can use 2-phase or even 4-phase modulation • Advanced option for high
Slide 21: PWM Configuration
PWM Configuration • For 4-phase modulation, generate 2 more digital PWM carriers that are 90° out of phase • 4-phase results in higher performance • Downside → Inductor per half-bridge • 2-phase PBTL modulation sums currents before the inductor • Still have double available current • 4-phase only po
Slide 22: Summary & Conclusion
Summary & Conclusion mrS
Slide 23: Summary & Conclusion (1/3)
Summary & Conclusion (1/3) • Fully digital feedback loops have distinct advantages over analog feedback loops • Consistent (No component spread) • Configurable & Programmable • Both DM and CM output are controlled using digitized feedback • DM feedback loop used to suppress audible noise and distort
Slide 24: Summary & Conclusion (2/3)
Summary & Conclusion (2/3) • Highly configurable digital architecture • Configurable LLADC configuration • Parallel ADCs for higher performance • Easy to meet performance requirements • Configurable Loop filter Slices • DM and CM control loops • AX5689 (4CH) → 4DM feedback loops and 4CM feedback loo
Slide 25: Summary & Conclusion (3/3)
Summary & Conclusion (3/3) • High configurability creates high potential for optimization • How to easily leverage configurability for your application? • MPS Axign reference designs • Copy-ready designs • Optimized for thermal performance, audio quality and cost • MPS reference designs available so
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