Texas Instruments LMH6522EVAL Evaluation Module LMH6522EVAL/NOPB LMH6522EVAL/NOPB Hoja De Datos
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LMH6522EVAL/NOPB
1
1
1000 pF
4
6
0.01
P
F
CCOA-
CCOA+
GND
GND
TOUTA
0.01
P
F
C0A-
COA+
CCTOA
GND
GND
OUTA+
OUTA-
OUTA-
OUTA+
1
2
3
ROAG0+
0.01
P
F
0.01
P
F
0
JTX2-10
2
3
4
5
2
3
4
5
OUTA1_ P
OUTA1_ N
GND
DVGA
LMH6522
LOA-
LOA+
1.0E-6
P
H
1.0E-6
P
H
LOB+
1.0E-6
P
H
OUTA+
OUTA-
44
43
OUTA_P
OUTA_N
CTOA+
CTOA-
ROAG0-
0
Basic Operation
Transformers TINA– TIND can provide both impedance matching as well as single ended to differential
conversion. The board is shipped with 2:1 impedance ratio transformers (1.4:1 Voltage ratio) that will
match 50
conversion. The board is shipped with 2:1 impedance ratio transformers (1.4:1 Voltage ratio) that will
match 50
Ω
equipment with the 100
Ω
input impedance of the LMH6522 DVGA .
On the output side of the board are transformers TOUTA -TOUTD. The output transformers were chosen
to provide a good compromise between distortion performance and physical size. The LMH6522 is
capable of driving a wide range of load impedances. A 200
to provide a good compromise between distortion performance and physical size. The LMH6522 is
capable of driving a wide range of load impedances. A 200
Ω
load impedance was chosen for the
evaluation board to emulate performance with a 100
Ω
back terminated filter. Other configurations are
possible with minor rework of the evaluation board.
Capacitors CCOA± through CCOD± are installed to isolate the DVGA outputs from the output transformer
primary windings. The output resistors are 40.2
primary windings. The output resistors are 40.2
Ω
matching resistors. The output impedance of the
LMH6522 amplifier is very low (10
Ω
@ 50MHz), and the 40.2
Ω
resistors provide termination for the 100
Ω
load presented by the transformer when the evaluation board is connected to 50
Ω
test equipment. The
JTX–2–10T output transformers have a 1:2 impedance ratio.
The LMH6522 DVGA is configured to have a maximum gain of 26dB. The transformers and matching
resistors contribute a loss of approximately 7.5 dB. Gain through the board should measure approximately
18.6 dB.
resistors contribute a loss of approximately 7.5 dB. Gain through the board should measure approximately
18.6 dB.
Zoomed in portions of the input and output schematics are shown above in
and
. These
schematics show that the evaluation board, as shipped, has been built with single ended inputs and
outputs. The full signal path schematic is shown in
outputs. The full signal path schematic is shown in
and the full evaluation board schematic,
including the digital control portions is available in .PDF format upon request.
Figure 2. Output Schematic
2
AN-2072 LMH6522 Evaluation Board
SNOA552B – July 2011 – Revised May 2013
Copyright © 2011–2013, Texas Instruments Incorporated