LMH6554_14 Datasheet, PDF (18/24 Pages) National Semiconductor (TI) – LMH6554 2.8 GHz Ultra Linear Fully Differential Amplifier

LMH6554
SNOSB30O – OCTOBER 2008 – REVISED MARCH 2013
www.ti.com
ESD Protection
The LMH6554 is protected against electrostatic discharge (ESD) on all pins. The LMH6554 will survive 2000V
Human Body model and 250V Machine model events. Under normal operation the ESD diodes have no affect on
circuit performance. There are occasions, however, when the ESD diodes will be evident. If the LMH6554 is
driven by a large signal while the device is powered down the ESD diodes will conduct. The current that flows
through the ESD diodes will either exit the chip through the supply pins or will flow through the device, hence it is
possible to power up a chip with a large signal applied to the input pins. Using the shutdown mode is one way to
conserve power and still prevent unexpected operation.
Board Layout
The LMH6554 is a high speed, high performance amplifier. In order to get maximum benefit from the differential
circuit architecture board layout and component selection is very critical. The circuit board should have a low
inductance ground plane and well bypassed broad supply lines. External components should be leadless surface
mount types. The feedback network and output matching resistors should be composed of short traces and
precision resistors (0.1%). The output matching resistors should be placed within 3 or 4 mm of the amplifier as
should the supply bypass capacitors. Refer to Power Supply Bypassing for recommendations on bypass circuit
layout. Evaluation boards are available through the product folder on ti.com.
By design, the LMH6554 is relatively insensitive to parasitic capacitance at its inputs. Nonetheless, ground and
power plane metal should be removed from beneath the amplifier and from beneath R_F and R_G for best
performance at high frequency.
With any differential signal path, symmetry is very important. Even small amounts of asymmetry can contribute to
distortion and balance errors.
Evaluation Board
See LMH6554 Product Folder for evaluation board availability and ordering information.
18
Submit Documentation Feedback
Product Folder Links: LMH6554
Copyright © 2008–2013, Texas Instruments Incorporated