MT9196
Data Sheet
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.
SERIAL
PORT
DIGITAL GAIN
& TONES
FILTER/CODEC
TRANSDUCER INTERFACE
-6.1 dB or
-3.6 dB
HSPKR +
Receive
Receiver
Driver
75
Handset
Receiver
(150Ω)
PCM
D
in
-24 to
+21 dB
(3dB steps)
Receive
Filter Gain
0 to -7 dB
(1 dB steps)
-6 dB
HSPKR -
75
Side-tone
-9.96 to
+9 96dB
(3.32 dB steps)
DTMF,
Tone
Ringer
-11 dB
Speaker
Phone
Driver
0 dB
SPKR +
SPKR -
0/+8dB
+8 to -20dB
(4 dB steps)
RINGER
0 to -28 dB
(4 dB steps)
Auxiliary
Out
Driver
-12 dB
AUXout
Speakerphone
Speaker
(40Ω nominal)
34Ω min)
PCM
D
out
-24 to
+21 dB
(3 dB steps)
Transmit
Transmit Filter
Gain
0 to +7 dB
(1 dB steps)
Trans-
mit
Gain
-0.37 dB
or 8.93 dB
Trans-
mit
Gain
6.37 dB
5 dB
M
U
X
5 dB
AUXin AUX input
MIC+
H/F answer-
back mic
M + Transmitter
microphone
M-
Digital Domain
Analog Domain
Internal To Device
External To Device
Figure 3 - Audio Gain Partitioning
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
5
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
