ISL55210-ABEVAL1Z Intersil, ISL55210-ABEVAL1Z Datasheet - Page 2

• Manufacturer Part Number: ISL55210-ABEVAL1Z
• Description: Amplifier IC Development Tools ISL55210 Eval Diff. Amp, Active Balun
• Manufacturer: Intersil
• Type: Differential Amplifiersr
• Series: ISL55210r

Specifications of ISL55210-ABEVAL1Z

• Rohs: yes
• Product: Evaluation Board
• Tool Is For Evaluation Of: ISL55210
• Operating Supply Voltage: 3.3 V
• Description/function: Evaluation board to test the performance of the active balun
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Operating Supply Current: 34 mA
• For Use With: ISL55210

where only AC-coupled designs can be tested. Running a set of
parametric frequency response curves vs Av to the FDA output
pins in ADS, with the input impedances targeted to match an
R
Figure 2 where the blocking capacitors have been set to 10µF in
simulation to eliminate their effect.
This sweep is stepping the gain up in 2dB steps showing the
required resistor values and the expected F-3dB bandwidths.
Since the ISL55210 is a 4GHz gain bandwidth VFA based FDA,
the response bandwidth decreases with gain. The significant
S
12.56
15.81
25.06
31.55
39.72
50.00
19.91
GAIN
5.00
6.29
9.98
= 50Ω, gives the expected parametric response curves of
7.92
V/V
FIGURE 2. RESPONSE CURVES vs AV FOR THE ACTIVE BALUN WITH
40
35
30
25
20
15
10
5
0
1
14dB
GAIN
50Ω INPUT
(dB)
14
16
18
20
22
24
26
28
30
32
34
16dB 18dB
34dB
1040.51
1298.08
10
160.71
195.31
238.04
291.06
439.67
543.07
672.79
835.72
357.12
Rf
FREQUENCY (MHz)
TABLE 1.
20dB 22dB
32dB
2
14.29
12.06
10.08
8.35
3.70
2.98
2.40
1.92
6.87
5.61
4.57
Rg1
100
30dB
24dB
28dB
64.29
62.06
60.08
58.35
56.87
55.61
54.57
53.70
52.98
52.40
51.92
Rg2
Application Note 1831
26dB
GAIN = xdB
1000
SIMULATED
(MHz)
3900
1200
3155
2037
811
588
445
330
260
205
158
BW
benefit of using the common mode feedback loop to set the
input match is the vastly reduced resistor values. The action of
the common mode loop develops the input impedance largely
through feedback requiring very low input resistors to achieve the
match. This gives input noise figures <7dB for gains > 18dB
using the low noise ISL55210 in this circuit. The closed loop
bandwidths are also extended over typical approaches with a
resistor to ground since the noise gain will be 1 + Av/2.The
bandwidths at lower gains do not strictly follow a gain bandwidth
product type response showing significant bandwidth extension
at lower gains due to reduced phase margin effects.
The 16.4dB gain used as the setting for the active balun
evaluation board simulates very flat through 1GHz with
approximately 4GHz F-3dB bandwidth for the response to the
ISL55210 outputs. In fact the board shows a response shape set
by the blocking capacitors on the low end and the output
transformer on the high end. All of these elements are well
modeled and running a response simulation of Figure 1 gives the
expected shape of Figure 3 where the 6dB matching loss at the
output is modeled but the insertion loss of the output
transformer is not. That insertion loss is specified as 0.4dB
(hence the 16.4dB gain setting) but measures only 0.2dB. The
measured response on the board will have a nominal midband
gain of 10.2dB with a response shape very close to this
simulation. The simulation is predicting -0.5dB response flatness
from approximately 2MHz to 500MHz.
Full Evaluation Board Schematic
The schematic with power supply decoupling and the optional
output interfaces is shown in Figure 4.
FIGURE 3. FOR THE CIRCUIT ON THE ACTIVE BALUN BOARD OF
10.4
10.2
10.0
9.8
9.6
9.4
9.2
9.0
9.8
9.6
9.4
1M
FIGURE 1
2M
4M
10M
FREQUENCY (Hz)
20M
40M 100M 200M 400M
April 5, 2013
AN1831.0
1G