ADA4855-3 Analog Devices, ADA4855-3 Datasheet - Page 15

• Manufacturer Part Number: ADA4855-3
• Description: Single Supply, High Speed, Rail-to-Rail Output, Triple Op Amp
• Manufacturer: Analog Devices

Specifications of ADA4855-3

• Vcc-vee: 3V to 5.5V
• Packages: CSP
• -3db Bandwidth: 400MHz
• Slew Rate: 800V/µs
• Vos: 1mV
• Ib: 4.5µA
• # Opamps Per Pkg: 3
• Input Noise (nv/rthz): 6.5nV/rtHz

APPLICATIONS INFORMATION
GAIN CONFIGURATIONS
The ADA4855-3 is a single-supply, high speed, voltage feedback
amplifier. Table 6 provides a convenient reference for quickly
determining the feedback and gain set resistor values and
bandwidth for common gain configurations.
Table 6. Recommended Values and Frequency Performance
Gain
1
2
5
1
Figure 47 and Figure 48 show the typical noninverting and
inverting configurations and recommended bypass capacitor values.
Conditions: V
R
0 Ω
1 kΩ
1 kΩ
F
V
IN
S
V
R
= 5 V, T
IN
G
Figure 47. Noninverting Gain Configuration
R
Figure 48. Inverting Gain Configuration
G
R
N/A
1 kΩ
200 Ω
G
A
R
= 25°C, R
F
ADA4855-3
R
+
–
F
ADA4855-3
–
+
–V
+V
−3 dB SS
200
120
45
BW (MHz)
L
–V
S
+V
= 150 Ω.
S
S
S
0.1µF
0.1µF
10µF
10µF
0.1µF
0.1µF
10µF
10µF
0.1µF
0.1µF
Large Signal 0.1 dB
Flatness (MHz)
53
50
6
V
OUT
V
OUT
Rev. 0 | Page 15 of 20
1
20 MHz ACTIVE LOW-PASS FILTER
The ADA4855-3 triple amplifier lends itself to higher order
active filters. Figure 49 shows a 20 MHz, 6-pole, Sallen-Key
low-pass filter.
The filter has a gain of approximately 6 dB and flat frequency
response out to 14 MHz. This type of filter is commonly used at
the output of a video DAC as a reconstruction filter. The frequency
response of the filter is shown in Figure 50.
V
IN
–10
–20
–30
–40
–50
–60
–70
232Ω
10
R1
0
Figure 50. 20 MHz, Low-Pass Filter Frequency Response
1
1.69kΩ
C1
15pF
309Ω
R3
Figure 49. 20 MHz, 6-Pole Low-Pass Filter
R2
1kΩ
R7
261Ω
1.87kΩ
C3
15pF
C2
6.6pF
R5
R4
1kΩ
R9
FREQUENCY (MHz)
261Ω
–
+
OP AMP
R8
OUT2
1.43kΩ
C5
33pF
U1
C4
4.3pF
R6
10
R11
1kΩ
OUT1
–
OP AMP
+
C6
3pF
261Ω
U2
R10
OUT1
–
+
OP AMP
OUT3
U3
261Ω
OUT2
R12
ADA4855-3
100
OUT3
200
V
OUT