ip so c-30sept2010

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Challenges in Designing a Low Power Speech Processing SoC

-a designer’s perspective

S. Krishnakumar Rao C-DAC

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Agenda

About C-DAC Why low power? Technology and Process selection Low Power Design techniques Speech processor SoC ASTRA portfolio of IP

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About C-DAC

Scientific Society under DIT, Govt. of India Application oriented R&D in Electronics and IT Eleven development centres across India

Technologies High Performance Computing Professional Electronics Health Informatics Ubiquitous Computing Education and Training

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C-DAC, Thiruvananthapuram

VLSI Design Broadcast and Communication Power Electronics Control and Instrumentation Strategic Electronics Cyber Security Language Technologies

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VLSI Design Group at C-DAC(T)

Professional design services with a well developed infrastructure for customers to realize their ideas from concept-to-silicon and to product; competitively

Design & development of IP cores for semiconductors, in the processor, serial communication and bus interfacing area under the brand name ASTRA

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Why Low Power?

Limited Battery Capacity

For Minimal Heat Dissipation Heat Sink, System Size/Weight/Cost

For Chip/System reliability

Save Energy

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Low Power Design - Application areas

Bio-Medical Mobile Military Space

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Constraints in ASIC design

The main constraints are

Speed/Performance Power Area Cost (EDA, IP, NRE, Manpower..)

Primary constraints should be identified and prioritized for Technology & Process selection IP selection Design methodology

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Technology & Process selection

Criteria for selection Operating voltage Operating frequency Power dissipation Chip area Cost of production Yield

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Technology & Process: for Low Power Operating Voltage

Choose the technology based on operating voltage

Minimise power converters

Power consumption

Choose low leakage (HVT) cells for low frequency application

When frequency of operation increases LVT cells can be used to optimize critical paths

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Technology & Process: for Low Power Dynamic power reduces with technology scaling,

but leakage power increases

Development and fabrication cost increases with technology scaling

Availability of low power IP such as RAM, ROM & NVM

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Selection of Hard IP: RAM & ROM

Power consumption Macros with low standby current Power consumption can be reduced by efficient

usage Cost

Free IP available from vendors, if cost is of prime concern

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Selection of Hard IP: NVM

Require multiple voltage for operation

Design techniques can be adopted to reduce the power consumption of NVM

The NVM content can be copied and executed from the RAM and enabling the standby mode for NVM thereafter.

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Selection of Hard IP : NVM

Cost perspective: License fee Use available memory IP and avoid cost escalation for

customisation Evaluate options depending on IP availability and cost

An MTP can be replaced with an OTP using an efficient Memory management algorithm.

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Selection of Hard IP: Clock

management PLL Advantages

Variable clock frequency Highly stable clock with low jitter

Disadvantage Power consumption

Oscillator Pad Advantage

Less power consumption Disadvantage

Single frequency

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Low Power Design techniques

Industry has a bunch of low power design techniques. But are they all required for my design?

Select the design techniques wisely?

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17C-DAC/TVM/HDG/Sep-10

Low Power Design techniques

Clock gating Data gating Power gating Frequency scaling Voltage scaling Variable device threshold

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Clock gating

CLK

EN

EN1

GCLK

EN

D Q

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Clock gating Dynamic power reduction Define the Active mode of the chip Identify switching activity of various modules Apply clock gating efficiently Disadvantages

Area overhead CG without proper analysis may result in higher

power consumption for certain modules

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Data Gating

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Data Gating

Dynamic power reduction If not used efficiently Data gating will cause

More power consumption Area overhead Critical path violation

Switching activity of candidates to be analyzed prior to gating

Usually more effective for power reduction in bus-structures

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Power gating

Courtesy: Cadence Design Systems

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23C-DAC/TVM/HDG/Sep-10

Power gating Advantage

Leakage power reduction

Disadvantages Design complexity Verification complexity increases

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Voltage and Frequency scaling

Voltage & frequency scaling are done in tandem

Courtesy: Cadence Design Systems

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Speech Processor Application

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26C-DAC/TVM/HDG/Sep-10

NAADA - Speech processor SoC for low power speech processing applications Integrates in-house IP Features

1.2V single supply operation Low power consumption < 5mW Frequency of operation - 20MHz Integrated 1Mbit NVM 64KB RAM 32KB ROM

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“NAADA” integrates

OTP128KB

1.2V

ROM32KB1.2V

SRAM64KB1.2V

DSP Engine

CPU

Glue Logic Standard Cells

(1.2V, 130nm,LL)

DSP Engine

Volt. Doubler

In-house IPs Integrated

32-bit RISC processor DSP IPs

FFT & IFFT MAC

UART SPI

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ASTRA – IP Portfolio

Processor ER8051: 8-bit microcontroller compatible with Intel 8051 ER8085: 8-bit microprocessor compatible with Intel 8085 ER9101: 16-bit Bit Slice ALU ER902: 32-bit RISC Processor ERASP8051: Asynchronous 8-bit microcontroller

Peripheral ERRTC: Real Time Clock ERTIMER: 32-bit configurable timer ERDMA: 8237 compatible DMA controller ER15530: Manchester Encoder Decoder

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ASTRA – IP Portfolio Communication

ER16450: UART compatible with NS16450 ERUSB2: USB 2.0 Device Controller ERMAC: IEEE802.3 compliant 100Mbps Media Access

Controller ERGMAC: IEEE802.3 compliant 1Gbps Media Access Controller EROTG: USB2.0 On-The-Go Controller ERUSB2: USB2.0 Device Controller ERUSBHC: USB2.0 Host Controller ERSATAII: SATAII Host Controller ERPCIe: PCIe endpoint

Sigma-Delta ADC Mixed Signal IP

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Thank You