Data Sheet
FEATURES
Low noise
Voltage noise: 2.3 nV/√Hz
Current noise: 2 pA/√Hz
Wide bandwidth
Small signal: 235 MHz (VGAx); 80 MHz (output amplifier)
Large signal: 80 MHz (1 V p-p)
Gain range
0 to 24 dB (input to VGA output)
6 to 30 dB (input to differential output)
Gain scaling: 20 dB/V
DC-coupled
Single-ended input and differential output
Supplies: ±2.5 V to ±5 V
Low power: 140 mW per channel at ±3.3 V
Quad, 235 MHz, DC-Coupled VGA
and Differential Output Amplifier
AD8264
GENERAL DESCRIPTION
The
AD8264
is a quad, linear-in-dB, general-purpose variable
gain amplifier (VGA) with a preamplifier (preamp), and a flexible
differential output buffer. DC coupling, combined with wide
bandwidth, makes this amplifier a very good pulse processor.
Each channel includes a single-ended input preamp/VGA section
to preserve the wide bandwidth and fast slew rate for low dis-
tortion pulse applications. A 6 dB differential output buffer with
common-mode and offset adjustments enable direct coupling to
most modern high speed analog-to-digital converters (ADCs),
using the converter reference output for perfect dc matching levels.
The −3 dB bandwidth of the preamp/VGA is dc to 235 MHz,
and the bandwidth of the differential driver is 80 MHz. The
floating gain control interface provides a precise linear-in-dB scale
of 20 dB/V and is easy to interface to a variety of external circuits.
The gain of each channel is adjusted independently, and all
channels are referenced to a single pin, GNLO. Combined with
a multioutput, digital-to-analog converter (DAC), each section
of the
AD8264
can be used for active calibration or as a trim
amplifier.
Operation from a bipolar power supply enables amplification of
negative voltage pulses generated by current-sinking pulses into
a grounded load, such as is typical of photodiodes or photo-
multiplier tubes (PMT). Delay-free processing of wideband
video signals is also possible.
APPLICATIONS
Multichannel data acquisition
Positron emission tomography
Gain trim
Industrial and medical ultrasound
Radar receivers
FUNCTIONAL BLOCK DIAGRAM
ONE CHANNEL SHOWN
OPPx
PREAMP
6dB (2×)
IPPx
IPNx
100Ω
100Ω
VPOS
VNEG
BIAS
1kΩ
07736-001
VGAx
FIXED GAIN VGA
AMPLIFIER
18dB (8×)
+ ATTENUATOR
– –24dB TO 0dB
GAIN
INTERFACE
DIFFERENTIAL OUTPUT
AMPLIFIER 6dB (2×)
1kΩ
747Ω
107Ω
2kΩ
2kΩ
VOLx
VOHx
INTERPOLATOR
COMM
GNHx
GNLO
VOCM
OFSx
Figure 1.
Rev. B
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AD8264
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 6
Thermal Resistance ...................................................................... 6
Maximum Power Dissipation ..................................................... 6
ESD Caution .................................................................................. 6
Pin Configuration and Function Descriptions ............................. 7
Typical Performance Characteristics ............................................. 8
Test Circuits ..................................................................................... 20
Theory of Operation ...................................................................... 28
Data Sheet
Overview ..................................................................................... 28
Preamp ......................................................................................... 28
VGA ............................................................................................. 28
Post Amplifier ............................................................................. 29
Noise ............................................................................................ 29
Applications Information .............................................................. 30
A Low Channel Count Application Concept Using a Discrete
Reference ..................................................................................... 30
A DC Connected Concept Example ........................................ 31
Evaluation Board ............................................................................ 34
Connecting and Using the AD8264-EVALZ .......................... 34
Outline Dimensions ....................................................................... 37
Ordering Guide .......................................................................... 37
REVISION HISTORY
1/16—Rev. A to Rev. B
Changes to Features Section, General Description Section, and
Figure 1 .............................................................................................. 1
Changes to Figure 2 .......................................................................... 7
Changes to VGA Section ............................................................... 28
Updated Outline Dimensions ....................................................... 37
Changes to Ordering Guide .......................................................... 37
1/11—Rev. 0 to Rev. A
Changes to Figure 1 ...........................................................................1
Changes to Connecting and Using the AD8264-EVALZ Section
and Figure 117 ................................................................................ 34
Changes to Figure 118 ................................................................... 35
5/09—Revision 0: Initial Version
Rev. B | Page 2 of 40
Data Sheet
SPECIFICATIONS
V
S
= ±2.5 V, T
A
= 25°C, f = 10 MHz, C
L
= 5 pF, R
L
= 500 Ω per output (VGAx, VOHx, VOLx), V
GAIN
= (V
GNHx
− V
GNLO
) = 0 V,
V
VOCM
= GND, V
OFSx
= GND, gain range = 6 dB to 30 dB, unless otherwise specified.
Table 1.
Parameter
GENERAL PERFORMANCE
–3 dB Small Signal Bandwidth (VGAx)
–3 dB Large Signal Bandwidth (VGAx)
–3 dB Small Signal Bandwidth (Differential Output)
1
–3 dB Large Signal Bandwidth (Differential Output)
1
Slew Rate
Test Conditions/Comments
V
OUT
= 10 mV p-p
V
OUT
= 1 V p-p
V
OUT
= 100 mV p-p
V
OUT
= 2 V p-p
VGAx, V
OUT
= 2 V p-p
VGAx, V
OUT
= 1 V p-p
Differential output, V
OUT
= 2 V p-p
Differential output, V
OUT
= 1 V p-p
Pins IPPx
Pins IPPx at dc; ΔV
IN
/ΔI
BIAS
Pins IPPx
Pins IPPx at 10 MHz
Min
Typ
235
150
80
80
380
290
470
220
−5
4.2
2
7.9
2.3
2
9
72
45
3.5
<1
|V
S
| − 1.3
|V
S
| − 1.3
|V
S
| − 0.5
|<1|
|<5|
|<10|
AD8264
Max
Unit
MHz
MHz
MHz
MHz
V/μs
V/μs
V/μs
V/μs
μA
MΩ
pF
kΩ
nV/√Hz
pA/√Hz
dB
nV/√Hz
nV/√Hz
Ω
Ω
V
V
V
mV
mV
mV
Input Bias Current
Input Resistance
Input Capacitance
Input Impedance
Input Voltage Noise
Input Current Noise
Noise Figure (Differential Output)
Output-Referred Noise (Differential Output)
Output Impedance
Output Signal Range
−8
−3
Output Offset Voltage
V
GAIN
= 0.7 V, R
S
= 50 Ω, unterminated
V
GAIN
= 0.7 V (Gain = 30 dB)
V
GAIN
= −0.7 V (Gain = 6 dB)
VGAx, dc to 10 MHz
Differential output, dc to 10 MHz
Preamp
VGAx, R
L
≥ 500 Ω
Differential amplifier, R
L
≥ 500 Ω per side
Preamp offset
VGAx offset, V
GAIN
= 0.7 V
Differential output offset, V
GAIN
= 0.7 V
VGAx = 1 V p-p, differential output =
2 V p-p (measured at VGAx)
f = 1 MHz
f = 10 MHz
f = 35 MHz
VGAx = 1 V p-p, differential output = 2 V p-p
(measured at differential output)
f = 1 MHz
f = 10 MHz
f = 35 MHz
V
GAIN
= −0.7 V, f = 10 MHz
V
GAIN
= +0.7 V, f = 10 MHz
−6
−18
−38
+6
+18
+38
DYNAMIC PERFORMANCE
Harmonic Distortion
HD2
HD3
HD2
HD3
HD2
HD3
−73
−68
−71
−61
−60
−53
dBc
dBc
dBc
dBc
dBc
dBc
HD2
HD3
HD2
HD3
HD2
HD3
Input 1 dB Compression Point
−78
−66
−71
−43
−56
−20
7
−9.6
dBc
dBc
dBc
dBc
dBc
dBc
dBm
2
dBm
Rev. B | Page 3 of 40
AD8264
Parameter
Two-Tone Intermodulation Distortion (IMD3)
Test Conditions/Comments
VGAx = 1 V p-p, f
1
= 10 MHz, f
2
= 11 MHz
VGAx = 1 V p-p, f
1
= 35 MHz, f
2
= 36 MHz
V
OUT
= 2 V p-p, f
1
= 10 MHz, f
2
= 11 MHz
V
OUT
= 2 V p-p, f
1
= 35 MHz, f
2
= 36 MHz
VGAx = 1 V p-p, f = 10 MHz
VGAx = 1 V p-p, f = 35 MHz
V
OUT
= 2 V p-p, f = 10 MHz
V
OUT
= 2 V p-p, f = 35 MHz
Overload Recovery
Group Delay Variation
ACCURACY
Absolute Gain Error
3
V
GAIN
= 0.7 V, V
IN
stepped from 0.1 V p-p to
1 V p-p
1 MHz < f < 100 MHz, full gain range
−0.7 V < V
GAIN
< −0.6 V
−0.6 V < V
GAIN
< −0.5 V
−0.5 V < V
GAIN
< +0.5 V
0.5 V < V
GAIN
< 0.6 V
0.6 V < V
GAIN
< 0.7 V
−0.5 V < V
GAIN
< +0.5 V, ±2.5 V
V
S
±5 V
−0.5 V < V
GAIN
< +0.5 V, −40°C ≤ T
A
≤ +105°C
Single IC, −0.5 V < V
GAIN
< +0.5 V,
−40°C ≤ T
A
≤ +105°C
Multiple ICs, −0.5 V < V
GAIN
< +0.5 V,
−40°C ≤ T
A
≤ +105°C
−0.5 V < V
GAIN
< +0.5 V
−40°C ≤ T
A
≤ +105°C
0
−1.25
−1
−1.25
−3
Min
Typ
−68
−51
−49
−34
32
19
23
10
30
17
21
8
25
±1
0.2 to 2
±0.35
±0.25
±0.35
−0.2 to −2
±0.2
±0.3
±0.1 to ±0.25
±0.25
Data Sheet
Max
Unit
dBc
dBc
dBc
dBc
dBm
dBV
RMS
dBm
dBV
RMS
dBm
dBV
RMS
dBm
dBV
RMS
ns
ns
3
+1.25
+1
+1.25
0
dB
dB
dB
dB
dB
dB
dB
dB
dB
19.5
20.0
20 ± 0.5
24
11.9
11.9 ± 0.4
17.9
17.9 ± 0.4
70
−0.4
−0.4 ± +0.2
−1.2
−1.2 ± +0.4
200
1.5
1.5 ± 0.3
6
6 ± 0.5
20.5
dB/V
dB/V
dB
dB
dB
dB
dB
V
MΩ
μA
μA
μA
μA
ns
nA
nA
V
dB
dB
Output Third-Order Intercept
Gain Law Conformance
4
Channel-to-Channel Matching
−0.5
+0.5
GAIN CONTROL INTERFACE
Gain Scaling Factor
Over Temperature
Gain Range
Gain Intercept to VGAx
Over Temperature
Gain Intercept to Differential Output
Over Temperature
GNHx Input Voltage Range
Input Resistance
GNHx Input Bias Current
Over Temperature
GNLO Input Bias Current
Over Temperature
Response Time
OUTPUT BUFFER
VOCM Input Bias Current
Over Temperature
VOCM Input Voltage Range
Gain (VGAx to Differential Output)
Over Temperature
11.5
−40°C ≤ T
A
≤ +105°C
17.5
−40°C ≤ T
A
≤ +105°C
GNLO = 0 V, no gain foldover
ΔV
IN
/ΔI
BIAS
, −0.7 V < V
GAIN
< +0.7 V
−0.7 V < V
GAIN
< 0.7 V
−0.7 V < V
GAIN
< 0.7 V, −40°C ≤ T
A
≤ +105°C
−0.7 V < V
GAIN
< 0.7 V
−0.7 V < V
GAIN
< 0.7 V, −40°C ≤ T
A
≤ +105°C
24 dB gain change
−V
S
−0.9
12.2
18.2
+V
S
0
0.3
−40°C ≤ T
A
≤ +105°C
OFSx = 0 V, VGAx = 0 V
−40°C ≤ T
A
≤ +105°C
−1.4
5.75
2.5
+1.4
6.25
Rev. B | Page 4 of 40
Data Sheet
Parameter
POWER SUPPLY
Supply Voltage
Power Consumption
Quiescent Current
Test Conditions/Comments
Min
±2.5
Typ
AD8264
Max
±5
Unit
V
Power Dissipation
PSRR
V
S
= ± 2.5 V
V
S
= ± 2.5 V, −40°C ≤ T
A
≤ +105°C
V
S
= ± 3.3 V
V
S
= ± 3.3 V, −40°C ≤ T
A
≤ +105°C
V
S
= ± 5 V
V
S
= ± 5 V, −40°C ≤ T
A
≤ +85°C
5
V
S
= ± 2.5 V
V
S
= ±3.3 V
V
S
= ±5 V
From VPOS to differential output, V
GAIN
= 0.7 V
From VNEG to differential output, V
GAIN
= 0.7 V
65
70
81
79
79 ± 25
85
85 ± 30
99
99 ± 30
395
560
990
−15
−15
88
95
110
mA
mA
mA
mA
mA
mA
mW
mW
mW
dB
dB
1
2
Differential Output = (VOHx − VOLx).
All dBm values are calculated with 50 Ω reference, unless otherwise noted.
3
Conformance to theoretical gain expression (see Equation 1 in the Theory of Operation section).
4
Conformance to best-fit dB linear curve.
5
For supplies greater than ±3.3 V, the operating temperature range is limited to −40°C ≤ T
A
≤ +85°C.
Rev. B | Page 5 of 40
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