AD603SQ/883B2 AD [Analog Devices], AD603SQ/883B2 Datasheet - Page 19
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AD603SQ/883B2
Manufacturer Part Number
AD603SQ/883B2
Description
Low Noise, 90 MHz Variable Gain Amplifier
Manufacturer
AD [Analog Devices]
Datasheet
1.AD603SQ883B2.pdf
(24 pages)
EVALUATION BOARD
The evaluation board of the AD603 enables simple bench-top
experimenting to be performed with easy control of the
AD603. Built-in flexibility allows convenient configuration to
accommodate most operating configurations. Figure 48 is a
photograph of the AD603 evaluation board.
Any dual-polarity power supply capable of providing 20 mA is
all that is required, in addition to whatever test equipment the
user wishes to perform the intended tests.
Referring to the schematic in Figure 49, the input to the VGA is
single-ended, ac-coupled, and terminated in 50 Ω to accommodate
most commonly available signal generators.
GNEG
GPOS
0.1µF
10µF
25V
C1
C4
C7
VIN
Figure 49. Schematic of the AD603 Evaluation Board
+
W2
V+
R5
0Ω
V+
R1
0.1µF
Figure 48. AD603 Evaluation Board
C5
V–
V–
R6
R2
100Ω
V+
1
2
3
4
R7
+
GPOS
GNEG
VINP
COMM
C8
10µF
25V
AD603
G1
VPOS
VOUT
VNEG
FDBK
G2
GND
8
7
6
5
G3
R3
0Ω
V+
C9
C6
0.1µF
C2
0.1µF
G4
453Ω
W1
R4
C3
0.1µF
VO
V–
VOUT
Rev. H | Page 19 of 24
The output is also ac-coupled and includes a 453 Ω series
resistor. The gain of the AD603 is adjusted by connecting a
voltage source between the GNEG and GPOS test loops. A 0 Ω
resistor, R5, is provided, permitting ground reference of the
differential gain control inputs. For other gain configurations, a
signal generator may be connected to the test loops, or the
GNEG and/or GPOS pins may be biased. Either pin may be
driven to either polarity within the common-mode limits of
−1.2 V to +2.0 V; therefore, to invert the gain slope, simply
consider the GPOS as the reference and drive the GNEG pin
positively with respect to GPOS.
The AD603 includes built-in gain resistors selectable at the
FDBK pin. The board is shipped with the gain at minimum,
with a 0 Ω resistor installed in R3. For maximum gain, simply
remove R3. Because of the architecture of the AD603, the
bandwidth decreases by 10, but the gain range remains at 40 dB.
Intermediate gain values may be selected by installing a resistor
between the VOUT and FDBK pins.
Figure 50, Figure 51, and Figure 52 show the component and
circuit side copper patterns and silkscreen. A bill of materials is
shown in Table 5.
Figure 50. Component Side Copper
Figure 51. Circuit Side Copper
AD603