Datasheet

1
10 100
A
VMAX
(V/V)
0.01
0.1
1
10
V
INMAX
(V
P
)
2.7MHz5MHz
10MHz
20MHz
50MHz
100MHz
150MHz
V
OUT
= 1V
PP
V
G
= V
GMAX
I
RGMAX
= 2.3mA
R
F
=
1
K
*
R
G
*
A
VMAX
R
G
=
I
R
GMAX
V
INPUT
MAX
LMH6503
SNOSA78E –OCTOBER 2003–REVISED APRIL 2013 www.ti.com
CHOOSING R
F
AND R
G
R
G
is calculated using Equation 5. V
INPUTMAX
is the maximum peak input voltage (V
pk
) determined by the
application. I
RGMAX
is the maximum allowable current through R
G
and is typically 2.3mA. Once A
VMAX
is
determined from the minimum input and desired output voltages, R
F
is then determined using Equation 6. These
values of R
F
and R
G
are the minimum possible values that meet the input voltage and maximum gain constraints.
Scaling the resistor values will decrease bandwidth and improve stability.
(5)
(6)
Figure 60 illustrates the resulting LMH6503 bandwidths as a function of the maximum ( y axis) and minimum
(related to x axis) input voltages when V
OUT
is held constant at 1V
PP
.
Figure 60. Bandwidth vs. V
INMAX
and A
VMAX
ADJUSTING OFFSETS
Treating the offsets introduced by the input and output stages of the LMH6503 is accomplished with a two step
process. The offset voltage of the output stage is treated by first applying −1.1V on V
G
, which effectively isolates
the input stage and multiplier core from the output stage. As illustrated in Figure 61, the trim pot located at R14
on the LMH6503 Evaluation Board (LMH730033) should then be adjusted in order to null the offset voltage seen
at the LMH6503's output (pin 10).
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