OP271_15 Datasheet, PDF (9/12 Pages) Analog Devices – High-Speed, Dual Operational Amplifier

OP271
Dual 12-Bit Voltage Output DAC
0
The dual voltage output DAC shown in Figure 6 will settle to
–1
12-bit accuracy from zero to full scale in 2 ␮s typically. The
CMOS DAC-8222 utilizes a 12-bit, double-buffered input
–2 _{SINGLE OP AMP,}
CONVENTIONAL
–3
DESIGN
structure allowing faster digital throughput and minimizing
digital feedback.
–4
CASCADED
(TWO STAGES)
Fast Current Pump
Maximum output current of the fast current pump shown in
–5 _{LOW PHASE ERROR}
AMPLIFIER
–6
Figure 7 is ؎11 mA. Voltage compliance exceeds ؎10 V with
؎15 V supplies. The current pump has an output resistance
of over 3 M⍀ and maintains 12-bit linearity over its entire
output range.
–7
0.001
0.01
0.1
1.0
0.005
0.005
0.5
FREQUENCY RATIO – 1/␤ ␻/␻
Figure 5. Phase Error Comparison
Figure 5 compares the phase error performance of the low
phase error amplifier with a conventional single op amp
E amplifier and a cascaded two-stage amplifier. The low phase
error amplifier shows a much lower phase error, particularly for
frequencies where ␻ր〉␻_T<0.1. For example, phase error of
-0.1؇ occurs at 0.002 ␻ր〉␻_T for the single op amplifier, but
T _{at 0.11 ␻ր〉␻T for the low phase error amplifier.}
For more detailed information on the low phase error amplifier,
LE ^{see Application Note AN-107.}
R1
10k⍀
V_IN
R2
10k⍀
R3
10k⍀
2
1/2
OP271FZ
3
R5
1
100⍀
+15V
R4
10k⍀
8
5
7
1/2
OP271FZ
6
4
I_OUT =
V_IN
RS
= ^VIN =10mA/V
100⍀
–15V
Figure 7. Fast Current Pump
O +15V
10␮F
S _10V
B REFERENCE
VOLTAGE
5V
21
V_DD
DAC-8222EW
R_FBA
3
4 ^VREF^A
DAC A
I_OUTA ₂
10pF
2
O³
0.1␮F
8
–
1/2
OP271EZ
+
V_OUTA
I_OUT
؎11mA
12-BIT DATABUS PINS 6–17
AGND 1
4
–15V
0.1␮F
10␮F
22 ^VREF^B
DAC B
I_OUTB ₂₄
6_–
10pF
1/2
7
OP271EZ
18 _{DAC A/DAC B}
R_FBB
23
5₊
DAC
CONTROL
19 _LDAC
20 _WR
DGND
V_OUTB
Figure 6. Dual 12-Bit Voltage Output DAC
REV. A
–9–