Audio Hub Evolution. May

Transcription

1 Audio Hub Evolution

2 Audio Hubs A History What is an audio hub? Featurerich audio IC originally designed for mobile phones Integrates all necessary mixedsignal and analogue audio functions ADCs, DACs, mixers, gain control and digital interfaces Began as integration exercise in mobile handsets Addition of multimedia capability changed audio architectures Multiple new audio sources/destinations and use cases Changed performance requirements and power budgets Required many new discrete DACs, switches, amplifiers, LDOs Many glue components required to enable integration Lack of hifi audio experience in handset manufacturing plus power, cost & space budgets, together with timetomarket pressures, drove need for a black box solution The audio hub 2

3 Mobile Phone Design Challenges for Audio System design problems PCB area and height restrictions Noise sources within handset Pop and click suppression Transducer management Managing wide range of 3 rd party accessories Active and standby power consumption constraints Multiple clock domains Market problems Lack of system architecture standardisation in mobile phones Multiple audio IC suppliers with variable feature sets Rapidly changing features and new use case introduction In many cases, missing expertise 3

4 Integration of circuits already proven to integrate well in handsets and other batterypowered applications Hifi quality ADCs and DACs Efficient power amplifiers Switches, mixers and volume control Microphone interfacing Digital filters and sample rate converters Dynamic range control PLLs or FLLs Audio Hub as a Black Box Standard interfaces for simple integration I2C or SPI control I2S, PCM/TDM or PDM digital audio Analogue i/o 4

5 Tuning Consistency Audio hubs later found a new application as a tuning platform Ideally located within system for transducer management Programmable filtering and equalisation Dynamic range control and limiting Stereo widening and other effects 5

6 Tuning Consistency Transducer management drove development of additional DSP capabilities Userconfigurable filtering functions with targeted functionality Proved highly popular among system integrators Targeted functionality with limited configurability for ease of use Autonomy from host system software enabled lastminute tuning, Tuning possible even with finalised acoustics and stable host software 6

7 WM8958: Typical Audio Hub 7

8 Use Case Management Audio hubs recently extended digital audio connectivity Driven by slim modem trends and analogue interconnect problems Digital connections to multiple chipsets are now common Typically application processor, modem, FM and Bluetooth Another natural application for audio hubs is now emerging: use case management Almost all audio signals, analogue and digital, pass via audio hub Mixing and routing of signals of diverse formats is already supported on audio hubs Applying these to use case management is straightforward In many cases there are also power advantages, since there is no need to route signals via multiple processors 8

9 Ringtone (Left) Ringtone (Right) FM Radio (Left) FM Radio (Right) Handset MIC 1 Handset MIC 2 Must be able to set up and disable dotted paths without transients or interruptions on solid paths High Pass Filter Noise Reduction Loudspeaker (Mono) Dock (Left) Dock (Right) Voice Recognition S/W Use Case Management: Future Challenges Use case planning maps conceptual routing to a realworld network Challenging when network is asymmetric, heavily loaded and with nonobvious ICspecific constraints on resources L i n e L i n e 1 H P H P A D C L H I G H P A S S F I L T E R 0 D A C L S P K A D C R H I G H P A S S F I L T E R 0 D A C R e n H P H P L i n e 1 DIGITAL AUDIO I N T E R F A C E G P I O L i n e 9

10 Use case complexity is growing More audio channels and nonaudio signals using audio signal chain More sources and destinations of audio Permutations of use case transitions greatly increasing Use Case Management: Future Challenges IC complexity and feature set is growing Partly to accommodate greater number of digital channels Partly due to continuing integration of new functions to reduce BOM Complexity of tuning functions is increasing Greater programmability needed, without impacting ease of use Much greater demand for real time processing resources Challenge is to maintain ease of use 10

11 Audio Hubs as a New Class of DSP Audio hubs are already providing a platform for transducer tuning functions and use case management Simplicity of integration and ease of use remain fundamental However, use case complexity is increasing dramatically and demands for more advanced algorithms are driving a need for greater flexibility Some audio hubs recently released by Wolfson already use a new internal structure to meet these demands Dedicated usecase management hardware Multichannel audio hardware engine with soft configuration Provides greater processing power without sacrificing easeofuse 11