LMH6554_15 Datasheet, PDF (21/29 Pages) Texas Instruments – LMH6554 2.8-GHz Ultra Linear Fully Differential Amplifier

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11 Layout
LMH6554
SNOSB30P – OCTOBER 2008 – REVISED JANUARY 2015
11.1 Layout Guidelines
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.
11.2 Layout Example
Figure 38. Layout Schematic
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