AD829
Figure 11. Large Signal Pulse Response of Inverting
Amplifier Using Current Feedback Compensation,
C
COMP
= 15 pF, C1 = 15 pF, R
F
= 1 k
Ω
, R1 = 1 k
Ω
15
12
9
CLOSED-LOOP GAIN (dB)
Figure 13. Large Signal Pulse Response of the Inverting
Amplifier Using Current Feedback Compensation,
C
COMP
= 1 pF, R
F
= 3 k
Ω
, R1 = 3 k
Ω
GAIN = –4
–3dB @ 8.2MHz
GAIN = –2
6
3
–3dB @ 9.6MHz
GAIN = –1
0
–3dB @ 10.2MHz
–3
–6
–9
–12
–15
100k
V
IN
= –30dBM
V
S
= 15V
R
L
= 1k
R
F
= 1k
C
COMP
= 15pF
C
1
= 15pF
1M
10M
FREQUENCY (Hz)
100M
Figure 12. Closed-Loop Gain vs. Frequency for the Circuit
of Figure 9
Figure 14. Small Signal Pulse Response of Inverting
Amplifier Using Current Feedback Compensation,
C
COMP
= 4 pF, R
F
= 1 k
Ω
, R1 = 1 k
Ω
15
12
9
CLOSED-LOOP GAIN (dB)
Figure 13 is an oscilloscope photo of the pulse response of a
unity gain inverter that has been configured to provide a small
signal bandwidth of 53 MHz and a subsequent slew rate of
180 V/µs; resistor R
F
= 3 kΩ and capacitor C
COMP
= 1 pF. Figure 14
shows the excellent pulse response as a unity gain inverter, this
using component values of R
F
= 1 kΩ and C
COMP
= 4 pF.
Figures 15 and 16 show the closed-loop frequency response of the
AD829 for different closed-loop gains and different supply voltages.
If a noninverting amplifier configuration using current feedback
compensation is needed, the circuit of Figure 17 is recommended.
This circuit provides a slew rate twice that of the shunt com-
pensated noninverting amplifier of Figure 18 at the expense of
gain flatness. Nonetheless, this circuit delivers 95 MHz bandwidth
with
±
1 dB flatness into a back terminated cable, with a differ-
ential gain error of only 0.01% and a differential phase error of
only 0.015° at 4.43 MHz.
GAIN = –4
C
COMP
= 2pF
GAIN = –2
6
3
GAIN = –1
0
–3
–6
–9
–12
–15
1
V
S
= 15V
R
L
= 1k
R
F
= 1k
V
IN
= –30dBM
C
COMP
= 3pF
C
COMP
= 4pF
10
FREQUENCY (MHz)
100
Figure 15. Closed-Loop Frequency Response for the
Inverting Amplifier Using Current Feedback Compensation
–12–
REV. G
AD [ ANALOG DEVICES ]
