AD8014AR Analog Devices Inc, AD8014AR Datasheet - Page 8

• Manufacturer Part Number: AD8014AR
• Description: IC OPAMP CF LP LN LDIST 8SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD8014AR

• Rohs Status: RoHS non-compliant
• Amplifier Type: Current Feedback
• Number Of Circuits: 1
• Slew Rate: 4600 V/µs
• -3db Bandwidth: 480MHz
• Current - Input Bias: 5µA
• Voltage - Input Offset: 2000µV
• Current - Supply: 1.15mA
• Current - Output / Channel: 50mA
• Voltage - Supply, Single/dual (±): 4.5 V ~ 12 V, ±2.25 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Output Type: -
• Gain Bandwidth Product: -

AD8014
Note: On Figures 19 and 20 R
20 pF.
APPLICATIONS
CD ROM and DVD Photodiode Preamp
High speed Multi-X CD ROM and DVD drives require high
frequency photodiode preamps for their read channels. To mini-
mize the effects of the photodiode capacitance, the low imped-
ance of the inverting input of a current feedback amplifier is
advantageous. Good group delay characteristics will preserve the
pulse response of these pulses. The AD8014, having many ad-
vantages, can make an excellent low cost, low noise, low power,
and high bandwidth photodiode preamp for these applications.
Figure 20. Large Signal Step Response; V
V
O
Figure 19. Large Signal Step Response; V
V
= 2 V Step
O
= 4 V Step
F
= 500 , R
S
= 50
S
= +5 V,
S
= ± 5 V,
and C
L
=
–8–
Figure 21 shows the circuit that was used to imitate a photo-
diode preamp. A photodiode for this application is basically a
high impedance current source that is shunted by a small ca-
pacitance. In this case, a high voltage pulse from a Picosecond
Pulse Labs Generator that is ac-coupled through a 20 k
tor is used to simulate the high impedance current source of a
photodiode. This circuit will convert the input voltage pulse into
a small charge package that is converted back to a voltage by the
AD8014 and the feedback resistor.
In this case the feedback resistor chosen was 1.74 k , which is a
compromise between maintaining bandwidth and providing
sufficient gain in the preamp stage. The circuit preserves the
pulse shape very well with very fast rise time and a minimum of
overshoot as shown in Figure 22.
INPUT
Figure 21. AD8014 as a Photodiode Preamp
500mV/DIV
OUTPUT
20V/
INPUT
0.1 F
DIV
CH1 20.0V
1
2
49.9
Figure 22. Pulse Response
20k
TEK RUN: 2.0GS/s ET AVERAGE
CH2 500mV M 25.0ns CH4 380mV
AD8014
1.74k
+5V
–5V
T[
]
49.9
OUTPUT
(10
(NO LOAD)
PROBE)
Rev. C
resis-