RHF350 STMICROELECTRONICS [STMicroelectronics], RHF350 Datasheet - Page 10

• Manufacturer Part Number: RHF350
• Description: Rad-hard 550 MHz low noise operational amplifier
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Power supply considerations
3
Single power supply
10/23
Power supply considerations
Correct power supply bypassing is very important to optimize performance in high-
frequency ranges. The bypass capacitors should be placed as close as possible to the IC
pins to improve high-frequency bypassing. A capacitor greater than 1 F is necessary to
minimize the distortion. For better quality bypassing, a 10 nF capacitor can be added. It
should also be placed as close as possible to the IC pins. The bypass capacitors must be
incorporated for both the negative and positive supply.
Figure 24. Circuit for power supply bypassing
In the event that a single supply system is used, biasing is necessary to obtain a positive
output dynamic range between the 0 V and +V
V
The amplifier must be biased with a mid-supply (nominally +V
DC component of the signal at this value. Several options are possible to provide this bias
supply, such as a virtual ground using an operational amplifier or a two-resistance divider
(which is the cheapest solution). A high resistance value is required to limit the current
consumption. On the other hand, the current must be high enough to bias the non-inverting
input of the amplifier. If we consider this bias current (35 A maximum) as 1% of the current
through the resistance divider, to keep a stable mid-supply two resistances of 750
used.
The input provides a high-pass filter with a break frequency below 10 Hz which is necessary
to remove the original 0 V DC component of the input signal, and to set it at +V
Figure 25 on page 11
added to the gain network to ensure a unity gain at low frequencies in order to keep the right
DC component at the output. C
calculated with regard to the cut-off frequency of this low-pass filter.
OH
and V
OL
, the amplifier provides an output swing from +0.9 V to +4.1 V on a 100
illustrates a 5 V single power supply configuration. A capacitor C
Doc ID 15604 Rev 4
G
contributes to a high-pass filter with R
+
-
CC
supply rails. Considering the values of
+
AM00835
10 µF
+
10 nF
10 µF
10 nF
CC
/2), in order to maintain the
fb
//R
G
and its value is
CC
/2.
RHF350
can be
G
load.
is