DS_1903_032
73M1903 Data Sheet
100 K
R3
Rwtot 600
1
1200
where
.
Rwtot RW Rohswitch 2 Rbead
R2 100 K R3
Use 1% resistors for R1, R2, and R3
To select the value for C1, make the zero at around 10Hz.
1
10
. .
.
2 π 100 K C1
1
C1
. .
.
2 π 100 K 10
C1 0.15 uF
The blocking cap Cblock should also have the same frequency response, but due to the low impedance,
its value will be much higher, usually requiring a polarized cap. A blocking cap may also be needed on
the modem side of the transformer if the DC offset current of the transmit pins will exceed the current
rating of the transformer.
1
Cblock
. .
.
2 π 600 10
Cblock 27 uF
If you are using a Wet transformer design, as in the following figure:
The only difference is that the blocking capacitor, Cblock, it is removed. All other equations still hold true.
Rev. 2.0
39
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
