LMH6552SDEVAL National Semiconductor, LMH6552SDEVAL Datasheet - Page 14

• Manufacturer Part Number: LMH6552SDEVAL
• Description: BOARD EVALUATION FOR LMH6552
• Manufacturer: National Semiconductor
• Series: LMH®, PowerWise®r

Specifications of LMH6552SDEVAL

• Channels Per Ic: 1 - Single
• Amplifier Type: Differential
• Output Type: Differential
• Slew Rate: 3800 V/µs
• -3db Bandwidth: 1.5GHz
• Current - Output / Channel: 80mA
• Operating Temperature: -40°C ~ 85°C
• Current - Supply (main Ic): 22.5mA
• Voltage - Supply, Single/dual (±): 4.5 V ~ 12 V, ±2.25 V ~ 6 V
• Board Type: Fully Populated
• Utilized Ic / Part: LMH6552
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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When using the LMH6552 in single-to-differential mode, the
complimentary output is forced to a phase inverted replica of
the driven output by the common mode feedback circuit as
opposed to being driven by its own complimentary input. Con-
sequently, as the driven input changes, the common mode
feedback action results in a varying common mode voltage at
the amplifier's inputs, proportional to the driving signal. Due
to the non-ideal common mode rejection of the amplifier's in-
put stage, a small common mode signal appears at the out-
puts which is superimposed on the differential output signal.
The ratio of the change in output common mode voltage to
output differential voltage is commonly referred to as output
balance error. The output balance error response of the
LMH6552 over frequency is shown in the Typical Perfor-
mance Characteristics section.
To match the input impedance of the circuit in Figure 3 to a
specified source resistance, R
The equations governing R
operation are also provided in Figure 3. These equations,
along with the source matching condition, must be solved it-
eratively to achieve the desired gain with the proper input
termination. Component values for several common gain con-
figurations in a 50Ω environment are given in Table 1.
Table 1. Gain Component Values for 50Ω System SOIC
Package
Table 2. Gain Component Values for 50Ω System LLP
Package
FIGURE 3. Single Ended Input with Differential Output
12 dB
12 dB
Gain
Gain
0 dB
6 dB
0 dB
6 dB
357Ω
357Ω
357Ω
275Ω
275Ω
275Ω
R
R
F
F
76.8Ω
348Ω
169Ω
54.9Ω
IN
255Ω
127Ω
R
R
and A
G
S
G
, requires that R
V
for single-to-differential
56.2Ω
61.8Ω
76.8Ω
68.1Ω
107Ω
59Ω
R
R
T
T
T
|| R
26.4Ω
27.6Ω
30.9Ω
26.7Ω
28.7Ω
34Ω
IN
R
R
30003510
M
M
= R
S
.
14
The circuit shown in Figure 4 was used to measure S-param-
eters for a single-to-differential configuration. The S-parame-
ter plots in the Typical Performance Curves are taken using
the recommended component values for 0 dB gain.
SINGLE SUPPLY OPERATION
Single supply operation is possible on supplies from 5V to
10V; however, as discussed earlier, AC input coupling is rec-
ommended for low supplies such as 5V due to input common
mode limitations. An example of an AC coupled, single sup-
ply, single-to-differential circuit is shown in Figure 5. Note that
when AC coupling, both inputs need to be AC coupled irre-
spective of single-to-differential or differential-to-differential
configuration. For higher supply voltages DC coupling of the
inputs may be possible provided that the output common
mode DC level is set high enough so that the amplifier's inputs
and outputs are within their specified operating ranges.
FIGURE 4. Single Ended Input S-Parameter Test Circuit
FIGURE 5. AC Coupled for Single Supply Operation
(50Ω System)
30003509
30003554