LMH6518SQEVK National Semiconductor, LMH6518SQEVK Datasheet - Page 3

• Manufacturer Part Number: LMH6518SQEVK
• Description: KIT EVAL FOR LMH6518 VGA
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LMH6518SQEVK

• Channels Per Ic: 1 - Single
• Amplifier Type: Variable Gain
• Output Type: Differential
• -3db Bandwidth: 900MHz
• Operating Temperature: -40°C ~ 85°C
• Current - Supply (main Ic): 210mA
• Voltage - Supply, Single/dual (±): 4.75 V ~ 5.25 V
• Board Type: Fully Populated
• Utilized Ic / Part: LMH6518
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output / Channel: -
• Slew Rate: -
• Lead Free Status / Rohs Status: Supplier Unconfirmed

2. LMH6518 Evaluation Software Look:
Preamp
board, use a DC voltmeter to measure LMH6518 pin 6 and
7 voltages (or C
LMH6518 pin 6 potential (driven input) can be controlled
by varying the incoming signal offset (2.5V nominal) at J3
(SMA connector). If the two LMH6518 inputs are not offset
close to each other, as stated, measured results could be
affected. Some of the side-effects of input offset are: out-
put clipping, excess distortion, loss of bandwidth, or step
response anomalies.
Potentiometer R
any remnant output offset, especially useful when the
LMH6518 operating conditions change. For an effective
method of input offset adjustment, especially when the
LMH6518 is set for High Gain (HG/ 0 dB), monitor J1 and
J2 (outputs) SMA center pins (1.2V nominal) with a DVM
Ladder Attenuator: 0 dB to 20 dB. 10 steps. Each step
is 2 dB
Total Gain: This displays the total device gain (read only,
assuming 100Ω differential load across J2 and J1 SMA or
J8 and J7 outputs) based on the Preamp Gain and the
ladder attenuation selected
Filters: Full (no filter), 20 MHz, 100 MHz, 200 MHz, 350
MHz, 650 MHz, and 750 MHz.
Power Mode: Full power and Aux Hi-Z (with Aux Hi-Z, the
auxiliary output is turned off with approximately 60 mA re-
duction in 5V supply current)
Gain
Lo
Hi
18.8
38.8
0
25
14
(board bottom side) is provided to null
and R
16.8
36.8
2
19
, right hand side pads).
14.8
34.8
4
FIGURE 3. Evaluation Software Screen Shot
TABLE 2. LMH6518 Gain Map
12.8
32.8
6
10.8
30.8
8
Attenuation (dB)
3
4.0 Miscellaneous
1. Overlapping gain state: As shown in Table 2, one of the
28.8
8.8
10
set to read DC voltage and adjust R
voltage difference between these two outputs to less than
50 mV. This will reduce any input offset so that the output
can be observed.
possible gain states (18.8 dB) is covered by either Preamp
HG, or Preamp LG. This gain is possible with Preamp set
to High Gain and 20 dB ladder attenuation, or, with
Preamp set to Low Gain and 0 dB ladder attenuation.
Choose Preamp High Gain (with 20 dB ladder attenuation)
for best noise performance or Preamp Low Gain (with 0
dB ladder attenuation) for best distortion performance.
Preamp Gain: Hi Gain and Low Gain (with 20 dB differ-
ence between the two)
Write: To write the current setup on the GUI screen into
the LMH6518 registers. To change any of the LMH6518
operating registers, the adjustments should be made first,
followed by a single click on the “Write” button.
Read: To read back all LMH6518 registers for confirma-
tion and verification. If the register Read back is different
from the last Write state, the software displays an alert
window.
Exit: To close the application
26.8
6.8
12
24.8
4.8
14
22.8
2.8
16
30080601
20.8
0.8
18
25
to minimize the
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−1.16
18.8
20