mt9196asr1 Zarlink Semiconductor, mt9196asr1 Datasheet - Page 5

• Manufacturer Part Number: mt9196asr1
• Description: Fully Featured Digital Telephone Circuit With Built-in Filter/codec, Digital Gain Pads, Dtmf Generator, Tone Ringer, And Handset And Speakerphone Transducers
• Manufacturer: Zarlink Semiconductor

The transmit filter is designed to meet CCITT G.714 specifications. The nominal gain for this filter path is 0 dB (gain
control = 0 dB). Gain control allows the output signal to be increased up to 7 dB. An anti-aliasing filter is included.
This is a second order lowpass implementation with a corner frequency at 25 kHz. Attenuation is better than 32 dB
at 256 kHz and less than 0.01 dB within the passband.
An optional 400 Hz high-pass function may be included into the transmit path by enabling the Tfhp bit in the Control
Register 1 (address 0Eh). This option allows the reduction of transmitted background noise such as motor and fan
noise.
The receive filter is designed to meet CCITT G.714 specifications. The nominal gain for this filter path is 0 dB (gain
control = 0dB). Gain control allows the output signal to be attenuated up to 7 dB. Filter response is peaked to
compensate for the sinx/x attenuation caused by the 8 kHz sampling rate.
The Rx filter function can be altered by enabling the Dial EN control bit in Control Register 1 (address 0Eh). This
causes another low-pass function to be added with a 3 dB point at 1200 Hz. This function is intended to improve the
sound quality of digitally generated dial tone received as PCM.
Side-tone is derived from the Tx filter before the LP/HP filter section and is not subject to the gain control of the Tx
filter section. Side-tone is summed into the receive handset transducer driver path after the Rx filter gain control
SERIAL
PORT
PCM
PCM
D
D
in
out
DIGITAL GAIN
Digital Domain
(3 dB steps)
Receive
(3dB steps)
Transmit
& TONES
+21 dB
DTMF,
+21 dB
Ringer
-24 to
-24 to
Tone
Internal To Device
FILTER/CODEC
(3.32 dB steps)
Transmit Filter
(1 dB steps)
(1 dB steps)
Filter Gain
0 to +7 dB
0 to -7 dB
Side-tone
Figure 3 - Audio Gain Partitioning
Receive
-11 dB
+9 96dB
-9.96 to
Gain
Zarlink Semiconductor Inc.
MT9196
5
or 8.93 dB
-0.37 dB
Trans-
Gain
(4 dB steps)
(4 dB steps)
+8 to -20dB
mit
0 to -28 dB
-6 dB
TRANSDUCER INTERFACE
RINGER
0/+8dB
Analog Domain
6.37 dB
Trans-
Gain
mit
M
U
X
-6.1 dB or
-3.6 dB
Receiver
Auxiliary
Speaker
-12 dB
Phone
Driver
Driver
Driver
0 dB
Out
5 dB
5 dB
HSPKR +
HSPKR -
SPKR +
SPKR -
AUXout
AUXin
MIC+
M +
M -
External To Device
Transmitter
microphone
75
75
AUX input
H/F answer-
back mic
Data Sheet
Speakerphone
(40
34
Speaker
Receiver
Handset
(150 )
nominal)
min)