ANALOGDEVICES fAX-ON-DEHAND HOTLINE
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Page
12
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r.
ANALOG
HighSpeed,
LIllI DEVICES
FastSettlingIe UpAmp
.
FEATURES
Fat Settting Time
~O.1'" in 5OOns mex
0.01% in 2.5ps max
High Slew Rate: 100V/1lS min'
Low 10': 25nA max
Guaranteed VOl Drift: 3OIlVrC mex
High CMRR: BOdB min
Orive.5OOpF
Low Price
TO-99
FREQUENCY
COMPENSATION
r
OBS
APPLICATIONS
01A and AID Converlion
Wideband Amplifi8n
MultiplexeR
Pul. AmplifieR
AD509
PIN CONFIGURATION
INVERTING 2
INPUT
OLE
v-
~
2..
PRODUCT DESCRIPTION
The ADS09j, ADS09K and ADS09S are monolithic
operational amplifiers specifically designed for applications
requiring fast settling times to high accuracy. Other comparable dynamic parameters include a small signal bandwidth of
2OMHz, slew rate of lOOV/JlS min and a full power response
of 150kHz min. The devices are internally compensated for
all closed loop gains greater than 3, and are compensated with
a single capacitor for lower gains.
The input characteristics of the AD.509 are consistent with
0.01 % accuracy over limited temperature ranges; offset current
is 2SnA max, offset voltage is 8mV max, nullable to' zero, and
offset voltage drift is limited to 30p.V/'C max. PSRR and
CMRR are typically 90dB.
T
V+
!.
TOPVIEW
TE
PRODUCT HIGHLIGHTS
1. The ADS09 is internally compensated for all closed loop
gains above 3. and compensated with a single capacitor for
lower gains thus eliminating the c:laborate stabilizing techniques required by other high speed IC op amps.
2. The ADSO9 will drive capaciti~ loads of SOOpF without
deterioration in settling time. Larger capacitive loads
can be driven by tailoring the compensation to minimize
settling time.
3. Common Mode Rejection, Gain and Noise are compatible
with a 0.01 % accuracy device.
4. The ADSO9K and ADSO9S are 100% tested for minimum
slew rate and guaranteed to settle to 0.01% of its final
value in less than 2.Slls.
The ADS09 is designed for use with high speed D/A or AID
conveners where the minimum conversion time is limited by
the amplifier setding time. If 0.01 % accuracy of conversion
is required. a conversion cannot be made in a shoner period
than the time required for the amplifier to settle to within
0.01 % of its final value,
All devices are supplied in the TO-99 package. The ADS09j
and ADS09K are specified for 0 to +70oC temperatUte range;
the ADS09S for operation from -SSoC to +12SoC.
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ANALOGDEVICES fAX-ON-DEMAND HOTLINE
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AD509-SPECIFICATIONS
(@ %25°&andVs= %15Vdeunless
oth8lWi~e specified)
AD5O9J
Typ
Mas
MiD
AD5O9K
Max
Typ
AD509S
Typ
MiD
Max
Uaita
Model
MiD
OPEN LOOP GAIN
Vo = :t10V,RL2:2kO
TmiDtoT...,RL '" 2kO
7,500
5,000
15,000
10,000
7,500
15,000
10,000
7,500
15.000
VN
VN
OUTPUT CHARACTERISTICS
Voltage@RL = 2k.O,T....D[oT-
:10
:t 12
:10
:!:12
:tICI
:!:12
V
1.2
80'
20
J.6
120
l.5
80
20
2,0
120
1.5
100
20
2.0
120
MHz
MHz
VI.,...
FREQUENCY RESPONSE
Unity <din Small Sipal
Full Power Response
SlewRate, Unity Gain
SettlingTime
100.1%
100.01%
.
200
1.0
200
1.0
INPUT OFFSET VOLTAGE
Initial Offset
4
Input Offset Voltage T miDto T...
10
14
Input Off8CIVoltageVI.Supply,
T.....toT...
2OCt
5
OBS
INPUT BIASCURRENT
l'Di0ai
125
T...toT-
INPUT OFFSET CURRENT
Initial
T,,=minlOmax
INPUT IMPEDANCE
Differential
INPUT VOLTAGE RANGE
Differential
Commoo Mode
Common Mode Rejection
20
4()
100
74
: 15
: 10
90
INPUT NOISE VOLTAGE
f = 10Hz
f'" 100Hz
f=]OOIt}h
POWER SUPPLY
Rated Perfonnana:
Opcnting
QuicsceD[Current
TEMPERATURE RANGE
Opcnting. Rated Performanc:e
SIOtllF
100
30
19
250
SOO
100
50
100
10
4
0
-65
100
ILVN
25
50
10
25
50
nA
nA
50
100
at
: 15
,dO
90
50
80
::5
4
0
-65
Temperature Range
DoCto +70°C
DoCto + 70°C
-55"C to +12S"C
:!:5
+70
+ 150
-55
-65
MO
:!::i5
: 10
90
V
V
dB
100
30
]9
nV/Y'Hz
nV/Y'Hz
nVIY'Hz
6
V
V
mA
+ 125
+ 150
.C
.C
:!:20
4
Package Option*
H-o8A
H-o8A
H-o8A
"H-O8A = TO-99 Style Metal Can. For outline information see Package
Information section.
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100
:t 15
:!:20
6
ORDERING GUIDE
AD509JH ,
AD509KH
AD509SH
mV
mV
nA
nA
NOTES
SpecifICationS subject to cbanae without DOrice,
AU miA and mu specuJCations are guarm>teed,
SpecifJCaDoaSshown ill boldface are tared on all 'prodUCtion units at fmal
dectric:aI tat. Results from t~
tests are used to calculate outgoing quality
Ie¥$.
Model
8
11
200
400
::!:15
+70
+150
4
100
100
30
19
'
ms
,,"5
200
400
OLE
:20
500
2.5
100
:!:]5
:5
8
11
200
1.0
ANALOGDEVICES fAX-ON-DEMAND HOTLINE
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"
Applying
the AD509
-
APPLYING THE ADS09
EIN) of a typical
display. The resultant waveform of (Eo
ADS09 is shown in Figure 3. Note that the waveform crosses
the 1mV point representing 0.01 % ac~uracy in approximately
l.S/JS. The top trace represents the output signal; the bottom
trace represents the error signal.
MEASURING SETTLING TIME. Settling time is defined as
that period required for an amplifier output to swing from
0 volts to full scale, usually 10 voltS, and to settle to within
a specified percentage of tbe final output voltage. For high
accuracy systems, the accuracy requirement is normally
specified as either 0.1'.16(lo-bit accuracy) or 0.01'.16(12-bit
accuracy) of the 10 volt output level. The settling time
perioo is comprised of an initial propagation delay, an
additional time for the amplifier to slew to the vicinity of
10 volts, and a final time period to'recover from internal
saturation and other effects, and settle within the specified
error band. Because settling time depends on both .linear
and nonlinear factors, there is no simple approach to
predicting itS final value to different levels of accuracy, ]n
particular, extremely high slew rates do not assure a rapid
scnling time, since this is only one of many factors affecting
settling time. In most high speed. amplifiers, after the
amplifier has slewed to the vicinity of tbe final output
voltage, it must recover from internal saturation and then
allow any overshoot and ringing to damp out. These
definitions are illustrated in Figure 1.
I
II
OUTPUT
ERROR
SIGNAL
OBS
j SLEWING
-SETTLING
,..
--
t ....1--r11m'
T
n.
3. Settling Time of AD509
SETTLING TIME VS. Rf AND Ri. Settling time of an
amplifier is a function of the feedback and input resistors,
since they interact with the input capacitance of the amplifier.
When operating in the non-inverting mode, the source
impedance should be kept relatively low; e.g., Sill; in order
to insure optimum performance. The small feedback
capacitor (SpF) is used in the settling time test circuit in
parallel with tbe feedback resistor to reduce ringing. This
capacitor partially cancels the pole formed in the loop gain
response as a result of the feedback and input resistors, and
the input capacitance.
OLE
E::~~{r!~~~!~~~:~=:===~--,-Eo - AE
DEAO
TIME
Figure
i
.0
.
I
TE
SETTLING TIME VS. CAPACIT]VE LOAD. The ADS09
will drive capacitive loads of SOOpF without appreciable
deterioration in settling time. Larger capacitive loads can be
dtiven by tailoring the compensation to minimize settling
time, Figure 4 shows the settling time of a typical ADS09,
compensated for unity gain witb a 1SpF capacitOr, with a
SOOpF capacitive load on the output. Note that settling time
to 0.01 % is still under 2.01-15.
~
IRECOIIERYLINEAR SETTLING
TIME To1:..:lE-1
OR .:!:~: x100%
Figure 1. Settling Time
OIJTP\IT I
1/
The AD509K and AD509S are guaranteed to settle to 0.1%
in SOOnsand 0.01" in 2.S/JS when tested as shown in Figure 2.
There is no appreciable degradation in settling time when
the capacitive load is increa.scd to 500pF, as discussed below.
The settling time is computed by summing the output and the
input into a differential amplifier, which then drives a scope
ERROR
SIGNAL
,
I
i,
no
m
t
i-
f1$
-
Figure 4. AD509 with 500pF Capacitive Load
5f>f
DECOUI'lING CAPACITORS
OMITTED fOR CLARITY
SUGGESTIONS FOR MINIMIZING SETTL]NG TIME. The
ADS09 has been designed to settle to 0.01 % accuracy in
1 to 2.S/JS. However, this amplifier is only a building block
in a circuit that also has a feedback network, input and output
connections, power supply connections, and a number of
external componentS. What has been painsta.kingly gained in
amplifier design can be lost without careful circuit design,
Some of the elements of a good high speed design are..........
CONNECTIONS. It is essential that care be taken in the.
signal and power ground circuits to avoid inducing or
generating extraneous voltages in the ground signal paths.
SCOI'£
fin
Figure 2. AD509 Settling Time Test Circuit
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ANALOGDEVICES fAX-ON-DEMAND HOTLINE
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15
"
AD509
[n addition, it is suggested that all connections be sbort and
direct, and as physically dose to the case as possible, so that
the length of any conducting path shared by external
components will be minimized.
.
The O.lIlF cetatnic power supply bypass capacitors are
considerably more important for the AD509 than for low
frequency general purpose amplifiers. Their main purpose
is to convert the distributed high frequency ground to a
'lumped singJe point (the V+ point). The V+ to V- O.lIlF
capacitor equalizes the supply grounds while the O.lIlF
capacitor from V+ to signal ground should be returned to
signal common. The signal common, which is bypassed to
pin 7, is defined as that point at which the input signal
source, tltc feedback network, and tbe retUrn side of the load
are joined to the power common,
COMPONENTS. Resistors are preferably metal fIlm types.
because they have less capacitance and stray inductance
than wire wound types, and are available with excellent
accuracies and temperatUre coefficients.
Diodes are hot carrier types for the very fastest-settling
applications, but lN914 types are suitable for more
routine uses.
Note that the diagram shows each individual capacitor
directly connected to the appropriate terminal (pin 7 [V+).
OBS
Capacitors in critical locations are polystyrene, teflon, or
polycarbonate to minimize dielectric absorption.
CIRCUIT. For the fastest settling times, keep leads short,
orient components to minimize stray capacitance, keep
circuit impedance levels as low as consistent with the output capabilities of the amplifier and the signal source,
reduce all extemalload capacitances to the absolute
minimum. Don't overlook sockets or printed circuit
board mounting as possible sources of dielectric absorption.
Avoid pole-zero mismatches in any feedback networks used
with the amplifier. Minimize noise pickup,
TO SIGNAL
COMMON
POINT
INVERTING
INPUT
OUTPUT
_INVERTING
INPUT
OLE
O.,..F
CEIlAMIe OISe
Figunt 5. Configuration for Unity Gain Applications
DYNAMIC RESPONSE OF ADS09
120
8'
..!
z'"
~:i
~
...
10
80
<10
20
II
-20
.0
100
..
1011
1OOOt
FREQUENCY-II,
1M
10M
-20
.0
100M
THE ADS09 AS AN OUTPUT AMPLIFIER FOR FAST
CURRENT -OUTPUT D-TO-A CONVERTERS
= .JCt~DAC)
-
101<
IOOIt
FREQUENCY H.
1M
10M
100M
'
The senling time of the combination depends on the settling
time of the DAC and the output amplifier. A good approximation is:
Is TOTAL
..
Figure 8 shows the AD509K connected as an output amplifier
with the ADS65K, high speed 12-bit IC digital-to-analog converter. The 10 picofarad capacitor, Cl, compensates for the
2SpF AD56S output capacitance. The voltage output of the
AD565K/ADS09K combination settles to :to.Ol% in one
microsecond. The low input voltage drift and high open loop
gain of the ADSO9K assures 12-bit accuracy over the operating
temperature range.
Most fast integrated circuit digital to analog converters have
current outputs. That is, the digital input code is translated
to an output current proportional to the digital code. In
many applications, that output current is converted to a voltage by connecting an operational amplifier in the current-to-
voltage convc:;rsionmode.
100
Figure7. Open Loop Frequency Response for VariousCc's
Figure 6. Open Loop Frequency and Phase Response
,
TE
30'
,100
2
+
AD566K
SkU
~
( ts AMP) 2
Some IC DACs settle to final output value in 100-500 nanoseconds. Since most IC op amps require a longer time to settle
to :1:0.1%or :1:0.01%of final value, amplifier settling time can
dominate total settling time. And for a 12-bit DAC, one least
significant bit is only 0,024% of full-scale, so low drift and
high linearity and precision are also required of tbe output
amplifier.
Figure8. AD509 as an Output Amplifier for B Fast CurrentOutput D-tO-AConvert",
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