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Zarlink Semiconductor Inc.
Zarlink, ZL and the Zarlink Semiconductor logo are trademarks of Zarlink Semiconductor Inc.
Copyright 2005-2007, Zarlink Semiconductor Inc. All Rights Reserved.
Zarlink has introduced a new generation family of
AEC (ZL38002 and ZL38004). Zarlink recommends
these products for new designs.
A full Design Manual is available to qualified
customers. To register, please send an email to
VoiceProcessing@Zarlink.com.
Features
• Handles up to -6 dB acoustic echo return loss
• 127 ms acoustic echo canceller
• Provides up to 12 dB of Noise Reduction
• Operate in two modes, Dual Analog mode and
single Analog mode (other port is digital PCM)
• PCM Data Formats in single Port mode- 16-bit
Linear, companded ITU-T A-law or U-law
• Advanced NLP design - full duplex speech with
no switched loss on audio paths
• Tracks changing echo environment quickly
• Adaptation algorithm converges even during
Double-Talk
• Designed for performance in high background
noise environments
• Provides protection against narrow-band signal
divergence
• Howling prevention eliminates uncontrolled
oscillation in high loop gain conditions
• AGC on speaker path
• Transparent data transfer and mute options
• Boot loadable for future factory software upgrades
• Serial micro-controller interface
• Two 16 bit linear ACD and DAC that meet ITU-T
G.711/712 recommendations
• Four Audio TX/RX Interfaces
• Differential Microphone Inputs
• Programmable Bias Voltage Output for Electret
microphones
• Microphone Presence Detection, Microphone
Mute
May 2007
Ordering Information
ZL38003GMG 81 Ball CBGA Trays, Bake & Drypack
ZL38003GMG2 81 Ball CBGA**Trays, Bake & Drypack
**Pb Free Tin/Silver/Copper
-40°C to +85°C
ZL38003
AEC with Noise Reduction & Codecs for
Digital Hands-Free Communication
Data Sheet
Figure 1 - Block Diagram
Serial
Microport
Interface
G.712
Codec
#1
Crosspoint
G.712
Codec
#0
AEC
Audio Interface
#3
Audio Interface
#2
Audio Interface
#1
Audio Interface
#0
AUXTONE
EAR
MIC
BIAS
MICDET
RESETB
EAR
MIC
BIAS
MICDET
EAR
MIC
EAR/SPEAKER
MIC
BIAS
MCLK
FPi
C4i
Rin
Sout Sin/Rin
Rout/Sout
SCLK
CS_CODEC
CS_AEC
DATA1
DATA2
PCM
Timing
ZL38003 Data Sheet
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Zarlink Semiconductor Inc.
• Multiple Gain pad settings
• Adjustable gain pads from -24 dB to +21 dB at Xin, Sin and Sout to compensate for different system
requirements
• Programmable Microphone Gain (0dB to +46.5 dB in 1.5 dB Steps)
• Side tone Mute, Programmable Side tone Gain (-39 dB to +6 dB in 3 dB Steps)
• User gain control provided for speaker path (-24 dB to +21 dB in 3 dB steps)
• Programmable Earpiece Gain (-28 dB to +2 dB in 2 dB Steps)
• RX Channel Mute, Programmable RX Volume control (-21 dB to 0 dB in 3 dB Steps)
• Differential Earpiece Driver Outputs (66 mW rms into 32 Ohms, 150 mW rms into 16 Ohms)
• Cross-Point Connects PCM Channels to any of the Four Audio TX/RX Interfaces
Applications
• Hands-free car kits
• Full duplex speaker-phone for digital telephone
• Echo cancellation for video conferences
• Intercom Systems
• Security Systems
1.0 Functional Description
The ZL38003 is an Acoustic Echo Canceller (AEC) with dual codec as shown in Figure 2. The ZL38003 provides
127 ms of acoustic echo cancellation, which makes it ideal for hand free car kits, and speaker phones designs.
Each of the codecs in the dual codec can be connected to 1 of 4 four analog ports through a cross point switch.
Also, the network side can be routed to a digital PCM interface that input/outputs either linear 2's complement or
A-/mu law commanded PCM data.
MT93L16 ZL38001 ZL38002 ZL38003
Description AEC for analog hands-
free communication
AEC for analog hands-
free communication
AEC with noise reduction for digital
hands-free communication
AEC with noise reduction & codecs
for digital hands-free communication
Application Analog Desktop phone
Analog Intercom
Analog Desktop phone
Analog Intercom
Hands-free Car Kits
Digital Desktop Phone Home Security
Intercom & Pedestals
Hands-free Car Kits
Digital Desktop Phone Home Security
Intercom & Pedestals
Features
AEC 1 channel 1 channel 1 channel 1 channel
LEC 1 channel 1 channel Custom Load Custom Load
Gains User Gain User Gain/18 dB
Gain on Sout
User Gain + System tuning gains User Gain + System tuning gains
Noise
Reduction
NN Y Y
Integrated
Codecs
N N N dual channel
Table 1 - Acoustic Echo Cancellation Family
ZL38003 Data Sheet
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Zarlink Semiconductor Inc.
2.0 Acoustic Echo Canceller (AEC) Description
The AEC section is comprised of an acoustic echo canceller, noise reduction and the operational control functions
for operation. The AEC guarantees clear signal transmission in both transmit and receive audio path directions
ensuring reliable voice communication even when low level signals are provided. The AEC does not use variable
attenuators during double-talk or single-talk periods of speech, as do many other acoustic echo cancellers for
speakerphones. Instead, the AEC provides high performance full-duplex operation similar to network echo
cancellers. This results in users experiencing clear speech and uninterrupted background signals during the
conversation and prevents subjective sound quality problems associated with “noise gating” or “noise contrasting”.
The AEC uses an advanced adaptive filter algorithm that is double-talk stable, allowing convergence even while
both parties are talking. This algorithm continually tracks changes in the echo path, regardless of double-talk, as
long as a reference signal is available for the echo canceller.
The echo tail cancellation capability of the acoustic echo canceller has been sized appropriately (127 ms) to cancel
echo in an average sized office or large size car with a reverberation time of less than 127 ms.
Figure 2 - AEC Block Diagram
Rout
Sin
Micro
Interface
Program
RAM
Program
ROM
Howling
Controller
NBSD
Linear/
µ/A-Law
R1
R1
S1S2
Linear/
µ/A-Law
HP
Filter
Linear
µ/A-Law/
Adaptive
Filter
HP
Filter
Sout
Rin
AGC User
Gain
+
-
-24 -> +21dB
ADV
NLP
Linear
µ/A-Law/
+
UNIT
CONTROL
Detector
Talk
Double
NBSD
Limiter
Limiter
ACOUSTIC ECHO PATH
Gain
Pad
Gain
Pad
Gain
Pad
Noise
Reduction
ZL38003 Data Sheet
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Zarlink Semiconductor Inc.
2.1 In addition to the echo cancellers, the following functions are supported:
• 12 dB of noise reduction
• User gain control provided for speaker path (-24 dB to +21 dB in 3 dB steps)
• Gain pads at the Sin and Sout ports plus one at the input of adaptive filter (XRAM)
• Control of adaptive filter convergence speed during periods of double-talk, far end single-talk and near-end
echo path changes
• Control of Non-Linear Processor thresholds for suppression of residual non-linear echo
• Howling detector to identify when instability is starting to occur and to take action to prevent oscillation
• Narrow-Band Detector for preventing adaptive filter divergence caused by narrow-band signals
• Programmable high pass filters at Rin and Sin for removal of DC components in PCM channels
• Limiters that introduce controlled saturation levels
• Serial controller interface compatible with Motorola, National and Intel micro controllers
• PCM encoder/decoder compatible with m/A-Law ITU-T G.711, m/A-Law Sign-Mag or linear 2’s complement
coding
• Automatic gain control on the receive speaker path
• Idle channel noise suppression
3.0 Dual Codec Description
The CODEC Dual Codec provides complete audio to PCM interfaces including filtering and optional data
companding as required by the ITU-T G.711 & G.712 recommendations. Programmable gain allows adjustment for
a wide range of transducer sensitivities - two microphone amplifiers and four ear piece amplifiers are provided to
allow connection to a handset, headset, auxiliary channel and microphone/speaker. A cross-point circuit allows
either codec to be connected to any of the four audio interfaces. Programmable voltage sources are available for
electret biasing on the Microphone channels.
PCM voice data is passed via a serial interface which operates in ST-BUS or GCI mode. ST-BUS mode allows
the Codecs to be allocated to any of the 32 available channels. Control and programming of the Codecs is carried
out over a flexible serial micro-controller interface.
ZL38003 Data Sheet
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Zarlink Semiconductor Inc.
Figure 3 - Block Diagram
Mic
Detect
Electret
Bias
u/A
Law
u/A
Law
G.712
Filtering
Sidetone
Cross-Point
Voice
Serial PCM
Interface
Control for companding mode, RX gain control(s), sidetone
level, RX hi-pass filter, cross-point, muting, electret biasing,
microphone pre-amp and gain, PLL
4
Serial
uPort
4
D
A
C
A
D
C
u/A
Law
u/A
Law
G.712
Filtering
Sidetone
D
A
C
A
D
C
Mic
Detect
Electret
Bias
Electret
Bias
VREF
PLL
SYSCLK VREFRESETB AUXTONE
Codec #1
Codec #0
Data
Data
Data
Data
Status
c Zarlink Semiconductor 2005 All rights reserved.
ISSUE
APPRD.
DATE
ACN
Package Code
Previous package codes
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