AD AD9630 Low distortion 750 mhz closed-loop buffer amp Datasheet

a
Low Distortion 750 MHz
Closed-Loop Buffer Amp
AD9630*
PIN CONFIGURATION
FEATURES
Excellent Gain Accuracy: 0.99 V/V
Wide Bandwidth: 750 MHz
Slew Rate: 1200 V/␮s
Low Distortion
–65 dBc @ 20 MHz
–80 dBc @ 4.3 MHz
Settling Time
5 ns to 0.1%
8 ns to 0.02%
Low Noise: 2.4 nV/√Hz
Improved Source for CLC-110
+VS 1
GENERAL DESCRIPTION
7 NC
NC 3
6 ***
INPUT 4
OBS
APPLICATIONS
IF/Communications
Impedance Transformations
Drives Flash ADCs
Line Driving
8 OUTPUT
** 2
AD9630
5 –VS
NC = NO CONNECT
**OPTIONAL +VS
***OPTIONAL –VS
NOTE: FOR BEST SETTLING TIME PERFORMANCE USE
OPTIONAL POWER SUPPLIES. ALL SPECIFICATIONS
ARE BASED ON USING SINGLE 6VS CONNECTIONS,
EXCEPT FOR SETTLING TIME TO 0.02% AND SMALL
SIGNAL S21. CONSULT THE FACTORY FOR VERSIONS
WITH OPTIONAL POWER SUPPLY PINS DISCONNECTED
INTERNAL TO THE PACKAGE.
OLE
The AD9630 is a monolithic buffer amplifier that utilizes a
patented, innovative, closed-loop design technique to achieve
exceptional gain accuracy, wide bandwidth, and low distortion.
Slew rate limiting has been overcome as indicated by the
1200 V/µs slew rate; this improvement allows the user greater
flexibility in wideband and pulse applications. The second harmonic distortion terms for an analog input tone of 4.3 MHz
and 20 MHz are –80 dBc and –66 dBc, respectively. Clearly,
the AD9630 establishes a new standard by combining outstanding dc and dynamic performance in one part.
TE
The large signal bandwidth, low distortion over frequency, and
drive capabilities of the AD9630 make the buffer an ideal flash
ADC driver. The AD9630 provides better signal fidelity than
many of the flash ADCs that it has been designed to drive.
Other applications that require increased current drive at unity
voltage gain (such as cable driving) benefit from the AD9630’s
performance.
The AD9630 is available in plastic DIP (N) and SOIC (R).
*Protected under U.S. patent numbers 5,150,074 and 5,537,079.
REV. B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1999
AD9630–SPECIFICATIONS
ELECTRICAL CHARACTERISTICS (unless otherwise noted, ⴞV = ⴞ5 V; R
S
Parameter
Test
Level
At DC
∆VS = ± 5%
± 2 V Full Scale
+25°C
Full
+25°C
Full
+25 to T MAX
TMIN
+25°C
+25 to T MAX
TMIN
Full
+25 to T MAX
TMIN
+25°C
Full
+25°C
I
IV
I
IV
II
VI
V
II
VI
VI
II
VI
V
VI
V
VO ≤ 0.7 V p-p
VO ≤ 0.7 V p-p
VO = 5 V p-p
VO = 5 V p-p
≤200 MHz
≤200 MHz
DC to 150 MHz
DC to 150 MHz
2 V p-p; 4.3 MHz
2 V p-p; 20 MHz
2 V p-p; 50 MHz
2 V p-p; 4.3 MHz
2 V p-p; 20 MHz
2 V p-p; 50 MHz
2 V p-p; 50 MHz
10 MHz
100 kHz – 200 MHz
TMIN to +25
TMAX
TMIN to +25
TMAX
Full
Full
+25°C
+25°C
Full
Full
Full
Full
Full
TMIN to +25
TMAX
+25°C
+25°C
II
II
V
V
II
II
V
V
IV
IV
II
IV
IV
II
II
V
V
400
330
VOUT = 5 V Step
VOUT = 1 V Step
VOUT = 1 V Step
VOUT = 5 V Step
VOUT = 5 V Step
VOUT = 2 V Step
+25°C
+25°C
TMIN to T MAX
+25°C
TMIN to T MAX
Full
IV
IV
IV
IV
IV
IV
700
VOUT = 2 V Step
VOUT = 2 V Step
VOUT = 2 V Step
VOUT = 2 V Step
4.4 MHz
4.4 MHz
TMIN to +25
TMAX
TMIN to +25
TMAX
+25°C
+25°C
IV
IV
IV
V
V
V
6
7
8
12
0.015
0.025
10
12
ns
ns
ns
ns
%
Degree
VCC = +5 V
VEE = –5 V
Full
Full
II
II
19
19
26
26
mA
mA
VOUT = 2 V p-p
VOUT = 2 V p-p
OBS
Output Voltage Range
Output Current (50 Ω Load)
Output Impedance
PSRR
DC Nonlinearity
FREQUENCY DOMAIN
Bandwidth (–3 dB)
Small Signal
Large Signal
Output Peaking
Output Rolloff
Group Delay
Linear Phase Deviation
2nd Harmonic Distortion
3rd Harmonic Distortion
Spectral Input Noise Voltage
Integrated Output Noise
TIME DOMAIN
Slew Rate
Rise/Fall Time
Overshoot Amplitude
Settling Time
To 0.1%
To 0.02%4
Differential Gain
Differential Phase
SUPPLY CURRENTS
VCC (+IS)
VEE (–I S)
= 50 ⍀, RLOAD = 100 ⍀)
Temp
Conditions
DC SPECIFICATIONS
Output Offset Voltage
Offset Voltage TC
Input Bias Current
Bias Current TC
Input Resistance
Input Capacitance
Gain
IN
Min
AD9630AN/AR
Typ
Max
±3
±8
±2
± 20
450
250
1.0
0.990
0.985
± 3.6
–8
–40
–25
–100
300
150
0.983
0.980
+3.2
50
40
44
OLE
+8
+40
+25
+100
Units
0.6
55
0.03
mV
µV/°C
µA
nA/°C
kΩ
kΩ
pF
V/V
V/V
V
mA
mA
Ω
dB
%
750
550
120
105
0.4
0
0.7
0.7
–80
–66
–52
–86
–75
–47
–46
2.4
32
MHz
MHz
MHz
MHz
dB
dB
ns
Degrees
dBc
dBc
dBc
dBc
dBc
dBc
dBc
nV/√Hz
µV
–3.2
TE
1200
1.1
1.3
4.2
5.0
2
1.2
0.3
–73
–58
–43
–79
–68
–41
–40
1.7
1.9
5.7
6.5
12
V/µs
ns
ns
ns
ns
%
NOTES
1
Short-term settling with 50 Ω source impedance.
Specifications subject to change without notice.
–2–
REV. B
AD9630
ABSOLUTE MAXIMUM RATINGS 1
Supply Voltages (± VS) . . . . . . . . . . . . . . . . . . . . . . . . . . . ±7 V
Continuous Output Current2 . . . . . . . . . . . . . . . . . . . . . 70 mA
Temperature Range over Which Specifications Apply
AD9630AN/AR . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C
Lead Soldering Temperature (10 sec) . . . . . . . . . . . . . +300°C
Storage Temperature
AD9630AN/AR . . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature3
AD9630AN/AR . . . . . . . . . . . . . . . . . . . . . . . . . . . . +150°C
NOTES
1
Absolute maximum ratings are limiting values to be applied individually, and
beyond which the serviceability of the circuit may be impaired. Functional
operability is not necessarily implied. Exposure to absolute maximum rating
conditions for an extended period of time may affect device reliability.
2
Output is short-circuit protected to ground, but not to supplies. Prolonged short
circuit to ground may affect device reliability.
3
Typical thermal impedances (part soldered onto board): Plastic DIP (N): θ JA =
110°C/W; θJC = 30°C/W; SOIC (R): θJA = 155°C/W; θ JC = 40°C/W.
OBS
ORDERING GUIDE
Model
Temperature
Range
EXPLANATION OF TEST LEVELS
Test Level
I 100% Production tested.
II 100% Production tested at +25°C and sample tested at
specified temperatures. AC testing of AN and AR grades
done on sample basis only.
III Sample tested only.
IV Parameter is guaranteed by design and characterization
testing.
V Typical value.
VI S Versions are 100% production tested at temperature
extremes. Other grades are sample tested at extremes.
100V
(5%, 0.25W)
+5V
1
0.1mF
8
AD9630 7 NC
NC 2
TOP VIEW
NC 3 (Not to Scale) 6 NC
4
OLE
Package
Description
–5.2V
5
24V
(5%, 0.25W)
NC = NO CONNECT
Package
Option
AD9630 Burn-In Circuit
AD9630AN
–40°C to +85°C 8-Lead Plastic DIP N-8
AD9630AR
–40°C to +85°C 8-Lead SOIC
SO-8
AD9630AR-REEL –40°C to +85°C 13" Tape and Reel SO-8
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD9630 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
THEORY OF OPERATION
The AD9630 is a wide-bandwidth, closed-loop, unity-gain
buffer that makes use of a new voltage-feedback architecture.
This architecture brings together wide bandwidth and high slew
rate along with exceptional dc linearity. Most previous widebandwidth buffers achieved their bandwidth by utilizing an
open-loop topology which sacrificed both dc linearity and frequency distortion when driven into low load impedances. The
design’s high loop correction factor radically improves dc linearity and distortion characteristics without diminishing
bandwidth. This, in combination with high slew rate, results in
exceptionally low distortion over a wide frequency range.
0.1mF
TE
WARNING!
ESD SENSITIVE DEVICE
Parasitic or load capacitance (>7 pF) connected directly to the
AD9630 output will result in frequency peaking. A small series
resistor (RS) connected between the buffer output and capacitive load will negate this effect. Figure 1 shows the optimal value
of RS as a function of CL to obtain the flattest frequency response. Figure 2 illustrates frequency response for various
capacitive loads utilizing the recommended RS.
50
RS
40
RSERIES – V
The AD9630 is an excellent choice to drive high speed and high
resolution analog-to-digital converters. Its output stage is designed to drive high speed flash converters with minimal or no
series resistance. A current booster built into the output driver
helps to maintain low distortion.
200V
"R"
CL
30
20
NO RS NEEDED
WHEN CL < 7pF;
FOR CL > 30pF, "R"
CAN BE OMITTED
10
0
0
7
20
40
60
80
CL – pF
Figure 1. Recommended RS vs. CL
REV. B
–3–
100
AD9630
the device output. To avoid this occurrence, the power supply
leads should be tightly twisted (if appropriate). Ferrite beads
mounted between the tantalum and ceramic capacitors will
serve the same purpose.
2
FREQUENCY RESPONSE – dB
1
10pF
0
25pF
–1
All unused pins (except the optional power supply pins) should
be connected to ground to reduce pin-to-pin capacitive coupling
and prevent external RF interference. If the source and drive
electronics require “remote” operation (> 1 inch from the
AD9630), the PC board line impedances should be matched
with the buffer input and output resistances. Basic microstrip
techniques should be observed. RIN and RS should be connected
as close to the AD9630 as possible.
50pF
–2
–3
–4
–5
–6
–7
–8
<0.1MHz
OBS
100MHz
200MHz
With only minimal pulse overshoot and ringing, the AD9630
can drive terminated cables directly without the use of an output
termination resistor (RS). Termination resistors (RS and R IN)
can be either standard carbon composition or microwave type.
For matching characteristic impedances, precision microwave
resistors of 1% or better tolerance are preferred.
300MHz
CL
Figure 2. Frequency Response vs. C L
with Recommended RS
OLE
In pulse mode applications, with RS equal to approximately
12 Ω, capacitive loads of up to 50 pF can be driven with minimal settling time degradation.
The AD9630 should be soldered directly to the PC board with
as little vertical clearance as possible. The use of zero insertion
sockets is strongly discouraged because of the high effective pin
inductances. Use of this type socket will result in peaking and
possibly induce oscillation.
The output stage has short circuit protection to ground. The
output driver will shut down if more than approximately
130 mA of instantaneous sink or source current is reached. This
level of current ensures that output clipping will not result when
driving heavy capacitive loads during high slew conditions,
although average load currents above 70 mA may reduce device
reliability.
LAYOUT CONSIDERATIONS
TE
+VS
Due to the high frequency operation of the AD9630 attention to
board layout is necessary to achieve optimum dynamic performance. A two ounce copper ground plane on the top side of the
board is recommended; it should cover as much of the board as
possible with appropriate openings for supply decoupling capacitors as well as for load and source termination resistors, (see
Figure 3).
1
4.7mF
0.1mF
0.1mF
2 *
VIN
AD9630
RIN
RS**
8
VOUT
6 *
5
0.1mF
Optimum settling time and ac performance results will be
achieved with surface mount 0.1 µF supply decoupling ceramic
chip capacitors mounted within 50 mils of the corresponding
device pins with the other side soldered directly to the ground
plane. For best high resolution (<0.02%) settling times, the optional power supply pins should be decoupled as shown above.
If the optional power supply pins are not used, they should be
left open.
0.1mF
4.7mF
–VS
*SEE PINOUTS
**SEE FIGURE 1
Figure 3. AD9630 Application Circuit
If surface mount capacitors cannot be used, radial lead ceramic
capacitors with leads less than 30 mils long are recommended.
Low frequency power supply decoupling is necessary and can be
accomplished with 4.7 µF tantalum capacitors mounted within
0.5 inches of the supply pins. Due to the series inductance of
these capacitors interacting with the 0.1 µF capacitors and
power supply leads, high frequency oscillations might appear on
–4–
REV. B
Typical Performance Curves – AD9630
1M
30
100
100k
25
80
10k
20
0
–300
RL = 100V
V
ppm
–400
–500
1k
–700
60
|Zo|
15
40
100
10
20
10
5
0
–600
–800
PHASE – Degrees
–200
V – |Zo|
RL = 200V
–100
–900
–1
0
VOLTS
1
3
2
OBS
1M
Figure 4. Endpoint DC Linearity
0
1M
1G
Figure 5. Input Impedance
50
50
50V
20
10
INTERCEPT – +dBm
30
40
TEST
CIRCUIT
50V
30
20
10
100M
10M
FREQUENCY – Hz
0
dc
1G
Figure 7. PSRR vs. Frequency
50
8
40
6
30
4
TE
–2
–4
–6
1
GAIN
0
–2
–3
–45
PHASE
–4
VIN = 100mV
–90
–5
–135
–6
–180
–20
OFFSET VOLTAGE
–30
–40
25
CASE TEMPERATURE – 8C
–50
125
Figure 9. Offset Voltage and Bias
Current vs. Temperature
Figure 10 . Forward Gain and Phase
RL = 100V
0
TEST CIRCUIT
50V
–3
–0.25
–4
50V
–5
–7
1G
0.25
RL = 50V
–2
–6
400M 600M
800M
FREQUENCY – Hz
0.5
0
–8
0M
REV. B
–10
RL = 200V
–1
–7
200M
–10
–55
VOLTS
0
MAGNITUDE – dB
2
VIN = 750mV
250
10
0
0
3
VIN = 100mV
1
–1
100
150
200
FREQUENCY – MHz
20
BIAS CURRENT
2
Figure 8. 2-Tone Intermodulation
Distortion
PHASE – Degrees
MAGNITUDE – dB
2
50
1G
10
–8
0
1M
10M
100M
FREQUENCY – Hz
Figure 6. Output Impedance
OLE
40
PSRR – dB
10M
100M
FREQUENCY – Hz
OFFSET VOLTAGE – mV
–2
6pF
–0.5
0
40
80
120
160
FREQUENCY – MHz
200
Figure 11. Frequency Response vs.
RLOAD
–5–
BIAS CURRENT – mA
1
–1000
–3
2ns/DIVISION
Figure 12. Small-Signal Pulse
Response
AD9630
0.1
0.1
TEST CIRCUIT
0.06
100V
6pF
0.04
0.02
0
–0.02
–0.04
–0.06
2.0
100V
10
20
30
TIME – ns
40
1.5
1.0
0.02
0
–0.02
0.5
0
–0.5
TEST CIRCUIT
50V
–1.0
–0.04
–1.5
–0.06
50V
6pF
–2.0
VOUT = 2V STEP
–0.1
1
50
OBS
Figure 13. Short-Term Settling Time
6pF
0.04
VOUT = 2V STEP
–0.1
2.5
0.06
–0.08
–0.08
10
100
1k
TIME – ns
10k
100k
Figure 14. Long-Term Settling Time
–2.5
–3.0
5ns/DIVISION
Figure 15. Large-Signal Pulse
Response
OLE
40
40
RL = 100V
RL = 100V
50
50
2nd
60
70
dBc
60
dBc
3.0
TEST CIRCUIT
VOLTS
SETTLING PERCENTAGE – %
SETTLING PERCENTAGE – %
0.08
0.08
3rd
2nd
70
80
80
90
90
3rd
100
100
1
10
FREQUENCY – MHz
100
Figure 16. Harmonic Distortion
VOUT = 4 V p-p
1
10
FREQUENCY – MHz
100
Figure 17. Harmonic Distortion
VOUT = 2 V p-p
–6–
TE
REV. B
AD9630
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead SOIC
(SO-8)
0.430 (10.92)
0.348 (8.84)
8
5
1
0.1968 (5.00)
0.1890 (4.80)
0.280 (7.11)
0.240 (6.10)
0.1574 (4.00)
0.1497 (3.80)
4
OBS
PIN 1
0.210
(5.33)
MAX
0.160 (4.06)
0.115 (2.93)
0.100 (2.54)
BSC
C1401a–0–12/99 (rev. B)
8-Lead Plastic DIP
(N-8)
0.325 (8.25)
0.300 (7.62)
0.060 (1.52)
0.015 (0.38)
0.130
(3.30)
MIN
5
1
4
0.2440 (6.20)
0.2284 (5.80)
PIN 1
0.0196 (0.50)
3 458
0.0099 (0.25)
0.0500 (1.27)
BSC
0.195 (4.95)
0.115 (2.93)
0.0098 (0.25)
0.0040 (0.10)
0.0688 (1.75)
0.0532 (1.35)
0.0192 (0.49)
0.0138 (0.35)
OLE
SEATING
PLANE
0.015 (0.381)
0.008 (0.204)
88
0.0500 (1.27)
0.0098 (0.25) 08
0.0160 (0.41)
0.0075 (0.19)
TE
PRINTED IN U.S.A.
0.022 (0.558) 0.070 (1.77) SEATING
0.014 (0.356) 0.045 (1.15) PLANE
8
REV. B
–7–