Datasheet

LMH6881
49.9:
49.9:
OUT+
OUT-
100:
50:
INPD
INMD
0.01 PF
+5V
1.25V
50:
AC
SOURCE
LOAD
V
CM
2.5V
0.01 PF
VCC
INMS
INPS
OCM
2.5V
0.01 PF
V
IN
2.5V
LMH6881
49.9:
49.9:
OUT+
OUT-
100:
50:
INPD
INMD
0.01 PF
+5V
OCM
1.25V
50:
AC
SOURCE
LOAD
V
CM
2.5V
V
CM
2.5V
0.01 PF
VCC
INMS
INPS
LMH6881
www.ti.com SNOSC72E –JUNE 2012–REVISED MARCH 2013
Figure 38. Typical Implementation with a Differential Input Signal
Figure 39. Typical Implementation with a Single-Ended Input Signal
INPUT CHARACTERISTICS
The LMH6881 has internally terminated inputs. The INMD and INPD pins are intended to be the differential input
pins and have an internal 100-Ω resistive termination. An example differential circuit is shown in Figure 38. When
using the differential inputs, the single-ended inputs should be left disconnected.
The INMS and INPS pins are intended to be used for single ended inputs and have been designed to support
single ended termination of 50 Ω working as an active termination. For single-ended signals an external 50-Ω
resistor is required as shown in Figure 39. When using the single-ended inputs, the differential inputs should be
left disconnected.
All of the input pins are self biased to 2.5 V. When using the LMH6881 for DC-coupled applications it is possible
to externally bias the input pins to voltages from 1.5 V to 3.5 V. Performance is best at the 2.5-V level specified.
Performance will degrade slightly as the common mode shifts away from 2.5 V.
The first stage of the LMH6881 is a low-noise amplifier that can accommodate a maximum input signal of 2 V
ppd
on the differential input pins and 1 V
pp
on either of the single-ended pins. Signals larger than this will cause
severe distortion. Although the inputs are protected against ESD, sustained electrical overstress will damage the
part. Signal power over 13 dBm should not be applied to the amplifier differential inputs continuously. On the
single-ended pins the power limit is 10 dBm for each pin.
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Product Folder Links: LMH6881