AD829JR Analog Devices Inc, AD829JR Datasheet - Page 13

• Manufacturer Part Number: AD829JR
• Description: IC VIDEO OPAMP LN HS 8-SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD829JR

• Slew Rate: 230 V/µs
• Mounting Type: Surface Mount
• Rohs Status: RoHS non-compliant
• Applications: Voltage Feedback
• Number Of Circuits: 1
• -3db Bandwidth: 120MHz
• Current - Supply: 5.3mA
• Current - Output / Channel: 32mA
• Voltage - Supply, Single/dual (±): ±4.5 V ~ 18 V
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• No. Of Amplifiers: 1
• Bandwidth: 600MHz
• No. Of Pins: 8
• Settling Time: 65ns
• Operating Temperature Max: 70°C
• Peak Reflow Compatible (260 C): No
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Table 4 gives the recommended C
as the corresponding slew rates and bandwidth. The capacitor
values were selected to provide a small signal frequency response
with <1 dB of peaking and <10% overshoot. For Table 4, ±15 V
supply voltages should be used. Figure 38 is a graphical extension of
Table 4, which shows the slew rate/gain trade-off for lower closed-
loop gains, when using the shunt compensation scheme.
Table 4. Component Selection for Shunt Compensation
Follower Gain
1
2
5
10
20
25
100
Figure 37. Noninverting Amplifier Connection Using External Shunt
100
10
1
V
1
IN
Figure 38. Value of C
CABLE
50Ω
C
Inverter Gain
−1
−4
−9
−19
−24
−99
COMP
50Ω
3
2
Compensation
COMP
AD829
NOISE GAIN
+
–
–V
4
and Slew Rate vs. Noise Gain
S
10
+V
7
S
COMP
R1 (Ω)
Open
1 k
511
226
105
105
20
0.1μF
5
C
and C
V
COMP
0.1μF
6
S
= ±15V
R2
R1
R2 (Ω)
100
1 k
2.0 k
2.05 k
2 k
2.49
2 k
SLEW RATE
LEAD
C
values, as well
LEAD
1kΩ
V
C
0
5
1
0
0
0
0
OUT
100
LEAD
1k
100
10
(pF)
Rev. H | Page 13 of 20
C
68
25
7
3
0
0
0
COMP
(pF)
CURRENT FEEDBACK COMPENSATION
Bipolar, nondegenerated, single-pole, and internally
compensated amplifiers have their bandwidths defined as
where:
f
I is the collector current of the input transistor.
C
r
kT/q approximately equals 26 mV at 27°C.
Because both f
the dynamic behavior of an amplifier is limited. Because
then
This shows that the slew rate is only 0.314 V/μs for every mega-
hertz of bandwidth. The only way to increase the slew rate is to
increase the f
Unfortunately, an amplifier with a bandwidth of 10 MHz can
only slew at 3.1 V/μs, which is barely enough to provide a full
power bandwidth of 50 kHz.
The AD829 is especially suited to a form of current feedback
compensation that allows for the enhancement of both the full
power bandwidth and the slew rate of the amplifier. The voltage
gain from the inverting input pin to the compensation pin is
large; therefore, if a capacitance is inserted between these pins,
the bandwidth of the amplifier becomes a function of its feed-
back resistor and the capacitance. The slew rate of the amplifier
is now a function of its internal bias (2I) and the compensation
capacitance.
T
e
COMP
is the unity-gain bandwidth of the amplifier.
is the inverse of the transconductance of the input transistors.
Slew
Slew Rate (V/μs)
16
38
90
130
230
230
230
Slew
f
is the compensation capacitance.
T
=
f
T
Rate
2
Rate
π
T
, and that is difficult because of process limitations.
T
r
e
and slew rate are functions of the same variables,
=
= 4
1
C
C
COMP
COMP
2
π
I
kT
q
=
−3 dB Small Signal Bandwidth (MHz)
66
71
76
65
55
39
7.5
2
π
kT
q
I
C
COMP
AD829