AD8027AR-REEL7 Analog Devices Inc, AD8027AR-REEL7 Datasheet - Page 19

• Manufacturer Part Number: AD8027AR-REEL7
• Description: IC OPAMP R-R LDIST LN LP 8SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD8027AR-REEL7

• Rohs Status: RoHS non-compliant
• Amplifier Type: Voltage Feedback
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Slew Rate: 100 V/µs
• -3db Bandwidth: 190MHz
• Current - Input Bias: 4µA
• Voltage - Input Offset: 200µV
• Current - Supply: 6.5mA
• Current - Output / Channel: 120mA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 12 V, ±1.35 V ~ 6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Gain Bandwidth Product: -

WIDEBAND OPERATION
Voltage feedback amplifiers can use a wide range of resistor
values to set their gain. Proper design of the application’s
feedback network requires consideration of the following issues:
•
•
•
•
The AD8027/AD8028 have an input capacitance of 2 pF. This
input capacitance forms a pole with the amplifier’s feedback
network, destabilizing the loop. For this reason, it is generally
desirable to keep the source resistances below 500 Ω, unless
some capacitance is included in the feedback network. Likewise,
keeping the source resistances low also takes advantage of the
AD8027/AD8028’s low input referred voltage noise of
4.3 nV/√Hz.
With a wide bandwidth of over 190 MHz, the AD8027/AD8028
have numerous applications and configurations. The AD8027/
AD8028 part shown in Figure 57 is configured as a noninvert-
ing amplifier. An easy selection table of gain, resistor values,
bandwidth, slew rate, and noise performance is presented in
Table 5, and the inverting configuration is shown in Figure 58.
Table 5. Component Values, Bandwidth, and Noise
Performance (V
Noise Gain
(Noninverting)
1
2
10
Poles formed by the amplifier’s input capacitances with the
resistances seen at the amplifier’s input terminals
Effects of mismatched source impedances
Resistor value impact on the application’s voltage noise
Amplifier loading effects
Figure 57. Wideband Noninverting Gain Configuration
V
IN
R1 = R
R
S
G
= ±2.5 V)
R
(Ω)
50
50
50
SOURCE
R1
F
||R
G
–
+
AD8027/
AD8028
R
(Ω)
0
499
499
F
+V
–V
R
F
0.1μF
0.1μF
10μF
10μF
C1
C2
C3
C4
R
(Ω)
N/A
499
54.9
G
SELECT
–3 dB
SS BW
(MHz)
190
95
13
03327-A-056
V
OUT
Output
Noise with
Resistors
(nV/√Hz)
4.4
10
45
Rev. C | Page 19 of 24
CIRCUIT CONSIDERATIONS
Balanced Input Impedances
Balanced input impedances can help to improve distortion
performance. When the amplifier transitions from PNP pair to
NPN pair operation, a change in both the magnitude and
direction of the input bias current occurs. When multiplied
times imbalanced input impedances, a change in offset can
result. The key to minimizing this distortion is to keep the input
impedances balanced on both inputs. Figure 59 shows the effect
of the imbalance and degradation in distortion performance for
a 50 Ω source impedance, with and without a 50 Ω balanced
feedback path.
–100
–20
–30
–40
–50
–60
–70
–80
–90
R1 = R
0.1
V
Figure 58. Wideband Inverting Gain Configuration
G = +1
V
R
V
IN
OUT
S
L
R
C5
Figure 59. SFDR vs. Frequency and Various R
= 1kΩ
= +3V
F
F
= 0Ω
||R
= 2V p-p
R
G
G
R1
R
F
= 24.9Ω
–
AD8027/
+
AD8028
FREQUENCY (MHz)
1
+V
–V
R
R
C
F
F
F
= 49.9Ω
0.1μF
0.1μF
10μF
10μF
C1
C2
C3
C4
AD8027/AD8028
SELECT
03327-A-057
V
F
10
OUT
03327-A-058
20