Data Sheet
2.0
Applications
MT88E41
The circuit shown in Figure 6 illustrates the use of the MT88E41 device in a typical FSK receiver system. Bellcore
Special Report SR-TSV-002476 specifies that the FSK receiver should be able to receive FSK signal levels as
follows:
Received Signal Level at 1200Hz:
-32dBm to -12dBm
Received Signal Level at 2200Hz:
-36dBm to -12dBm
This condition can be attained by choosing suitable values of R1 and R2. The MT88E41 configured in a unity gain
mode as shown in Fig. 6 meets the above level requirements.
For applications requiring detection of lower FSK signal level, the input op amp may be configured to provide
adequate gain.
VDD
C1
R1
IN +
IN -
GS
R2
VRef
CAP
C2
Notes:
R1, R2 = 100 kΩ 1%
R3, R4 = 100 kΩ 10%
C1, C2, C3 = 0.1µF 20%
X-tal = 3.579545 MHz
X-tal
MT88E41
VDD
IC2
IC1
PWDN
CD
DR
DATA
DCLK
To
Controller
R3
C3
R4
OSC1
OSC2
VSS
Figure 6 - Application Circuit (Single-Ended Input)
SEMICMF.019
7