P2781TR ETAL [ETAL Group], P2781TR Datasheet - Page 4

• Manufacturer Part Number: P2781TR
• Description: MICROPROFILE LINE MATCHING TRANSFORMER
• Manufacturer: ETAL [ETAL Group]

The circuit of Fig. 6 gives good TX and RX
flatness (±0.3dBm 200Hz - 4kHz).
alternative arrangement, using existing PCB
sites, is shown in Fig. 7. Note, however, that TX
flatness will be degraded with the topology.
Frequency response driven by terminal
equipment (voltage scource with 430
resistance) measured across 600
600
±0.2dB 200Hz to 4kHz
ETALDOC 240/14
dB
F requency R esponse
F ig 3
Recommended Circuit
Fig 6
PERFORMANCE
-0.4
* If return loss > 16d B, 300Hz - 4kHz is acc eptable, b loc king
-0.1
-0.2
-0.3
Recommended Circuit
F ig 2
c ap a citor ma y b e rela xed to 4.7 F
100Hz
600
0
LINE
Ω
MATCH
200 300
6.8 F
μ
20%
500
+ _
6.8nF
*
5%
Frequency
1kHz
μ
+ 50%
_
20%
2
6.8nF
+ _
3
Ω
5%
4 5
Ω
is within
series
+ 2%
430
_
10
An
Page 4 of 5
Note:
To obtain harmonic distortion power in dBm, add
fundamental power in dBm to third harmonic in
dBc e.g. at -10dBm power in line at 450Hz, third
harmonic power is -10 + (-74) = -84dBm typical.
dB
Return Loss
T hird Harmonic Distortion vs. S ignal Level
F ig 4
F ig 5
Recommended Circuit
F ig 7
-14
-18
-22
-26
-30
-60
-65
-70
-75
-80
100Hz
-15
Funda mental
450Hz
200 300
Fundamental P ower (dBm)
500
-10
Frequency
Worst Case
1kHz
T ypic al
2
-5
P2781
October 2007
3
T yp ic al
4 5
10
0