SL3522CMC MITEL [Mitel Networks Corporation], SL3522CMC Datasheet - Page 8

• Manufacturer Part Number: SL3522CMC
• Description: 500MHz 75dB Logarithmic/Limiting Amplifier
• Manufacturer: MITEL [Mitel Networks Corporation]

8
SL3522
A PRACTICAL APPLICATION FOR THE SL3522
AS A LOG/LIMITING AMPLIFIER
large limited RF Output level (0dBm on each of two RF Output
pins (9 and10)) and a wide RF bandwidth (450MHz) in a small
28 pin Miniature Ceramic S.O package. As a result, there is a
tendency for the device to become unstable unless care is
used in the application.
BOARD” in Fig. 11 has proved reliably stable. The PCB is a
double layer Fibre epoxy board which uses SMDs where
possible. A circuit diagram for the Demonstration PCB appears
in Fig. 10.
application is realised practically:-
14 and 15 of the SL3522, to allow +5V to appear at both pins.
through the PCB to a Ground plane on the bottom side. It is
important to ensure that the impedance of each of these
connections is kept to an absolute minimum to prevent
instability. If these connections are achieved using through
plated holes, it is recommended that they are filled with solder
to lower their impedance.
connectors for the RF input, RF Output and Video Output
connections. These can be changed if necessary to an
alternative type, but it is vital to ensure that the ground plane
is solidly connected to the Guard Ring which surrounds the RF
Output tracks.
The SL3522, with the RF Output-Buffer ENABLED, has a
The PCB layout for a ”SL3522 DEMONSTRATION
The following points should be noted when this
1) A wire needs to connect the two pads connected to pins
2) ALL the GND connections to the SL3522 are made
3) The PCB is configured to accept SMA, SMB or SMC
–5V V
EE
28
RF INPUT
1
27
2
26
3
VIDEO LOADING
10n
10n
C3
C9
25
4
R 200
C 20p
Fig.10 SL3522 demonstration board circuit diagram
24
5
23
6
RF OUTPUT
22
SL3522
7
LK
21
8
mounting DC isolating BALUN transformer (e.g VANGUARD
VE43666, available from Vanguard Electronics Company Inc,
1480 West 178th St. GARDENA, C.A. 90248, U.S.A. Tel:-
U.S.A. (213) 323 – 4100) to couple a signal into the RF input
connections (pins 27 and 28). It is NOT recommended to
attempt operating the SL3522 with the RF Output Buffer
enabled, WITHOUT using an input BALUN, although it may be
possible, provided the input source impedance to both pins 27
and 28 remains balanced. The centre tap of the secondary
winding of the transformer should be soldered to the small
ground plane on the upper side of the PCB.
the SL3522 only, with pin 10 being terminated on the PCB
using a 51
and10 are terminated with equal impedances.
link (LK) between pin 8 of the SL3522 and the adjacent guard
track around the RF Output lines. Similarly, the buffer can be
disabled by removing the same link. When the buffer is
disabled, the following components can be omitted:-
adjusted using two 1k
included in the PCB layout.
of SL3522 devices used with the PCB layout detailed in Fig.11.
10n
C4
GAIN
ADJUST
VR
20
G
9
4) The PCB is configured to accept a small surface
5) The RF Output connection to the PCB is from pin 9 of
6) The RF Output Buffer can be enabled by soldering a
1nF capacitors (C1, C2)
10nF capacitor (C8)
51 resistor (R
7) The Slope (gain) and Offset of the Video Output can be
The plots in Fig. 12 to fig. 23 are typical of the performance
1k
C1
1n
19
10
resistor. It is important to ensure that both pin 9
R
R
1n
1k
C2
51
FO
G
18
11
FO
10n
1k5
C8
R
T
)
17
12
trimmers, provision for which is
R
1k
O
OFFSET
ADJUST
VR
10n
C7
13
16
0
1k
10n
C5
15
14
R
150
VS
+5V V
10n
C6
CC
OUTPUT
VIDEO