TSH11 Datasheet, PDF (4/5 Pages) STMicroelectronics – 120MHz BANDWIDTH MOS INPUT SINGLE OPERATIONAL AMPLIFIER

TSH11
EVALUATION CIRCUIT
50W
Input
1kW
+5V
10m F
10nF
10nF
10m F
-5V _1kW
50W
Output
CF
PRINTED CIRCUIT LAYOUT
As for any high frequency device, a few rules must
be observed when designing the PCB to get the
best performances from this high speed op amp.
From the most to the least important points :
u Each power supply lead has to be by-
passed to ground with a 10nF ceramic ca-
pacitor very close to the device and a 10µF
tantalum capacitor.
u To provide low inductance and low resist-
ance common return, use a ground plane
or common point return for power and sig-
nal.
u All leads must be wide and as short as pos-
sible especially for op amp inputs. This is in
order to decrease parasitic capacitance
and inductance.
u Use small resistor values to decrease time
constant with parasitic capacitance.
u Choose component sizes as small as pos-
sible (SMD).
u On output, decrease capacitor load so as
to avoid circuit stability being degraded
which may cause oscillation. You can also
add a serial resistor in order to minimise its
influence.
u One can add in parallel with feedback re-
sistor a few pF ceramic capacitor C_F adjust-
ed to optimize the settling time.
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