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14-Bit, 80 MSPS/105 MSPS
A/D Converter
AD6645
FEATURES
SNR = 75 dB, f
IN
15 MHz, up to 105 MSPS
SNR = 72 dB, f
IN
200 MHz, up to 105 MSPS
SFDR = 89 dBc, f
IN
70 MHz, up to 105 MSPS
100 dBFS multitone SFDR
IF sampling to 200 MHz
Sampling jitter: 0.1 ps
1.5 W power dissipation
Differential analog inputs
Pin compatible to AD6644
Twos complement digital output format
3.3 V CMOS compatible
Data-ready for output latching
generation in a wideband ADC family, preceded by the AD9042
(12-bit, 41 MSPS), the AD6640 (12-bit, 65 MSPS, IF sampling),
and the AD6644 (14-bit, 40 MSPS/65 MSPS).
Designed for multichannel, multimode receivers, the AD6645 is
part of the Analog Devices, Inc., SoftCell® transceiver chipset.
The AD6645 maintains 100 dB multitone, spurious-free dynamic
range (SFDR) through the second Nyquist band. This breakthrough
performance eases the burden placed on multimode digital
receivers (software radios) that are typically limited by the ADC.
Noise performance is exceptional; typical signal-to-noise ratio
(SNR) is 74.5 dB through the first Nyquist band.
The AD6645 is built on the Analog Devices extra fast
complementary bipolar (XFCB) process and uses an innovative,
multipass circuit architecture. Units are available in thermally
enhanced 52-lead PowerQuad 4 (LQFP_PQ4) and 52-lead
exposed pad (TQFP_EP) packages specified from −40°C to
+85°C at 80 MSPS and −10°C to +85°C at 105 MSPS.
APPLICATIONS
Multichannel, multimode receivers
Base station infrastructures
AMPS, IS-136, CDMA, GSM, W-CDMA
Single channel digital receivers
Antenna array processing
Communications instrumentation
Radars, infrared imaging
Instrumentation
PRODUCT HIGHLIGHTS
1.
IF Sampling. The AD6645 maintains outstanding ac
performance up to input frequencies of 200 MHz, suitable
for multicarrier 3G wideband cellular IF sampling receivers.
Pin Compatibility. The ADC has the same footprint and
pin layout as the AD6644 14-bit, 40 MSPS/65 MSPS ADC.
SFDR Performance and Oversampling. Multitone SFDR
performance of 100 dBFS can reduce the requirements of
high end RF components and allows the use of receive
signal processors, such as the AD6620, AD6624/AD6624A,
or AD6636.
2.
3.
GENERAL DESCRIPTION
The AD6645 is a high speed, high performance, monolithic 14-bit
analog-to-digital converter (ADC). All necessary functions,
including track-and-hold (T/H) and reference, are included on the
chip to provide a complete conversion solution. The AD6645
provides CMOS-compatible digital outputs. It is the fourth
AV
CC
DV
CC
FUNCTIONAL BLOCK DIAGRAM
AD6645
AIN
AIN
A1
TH1
TH2
A2
TH3
TH4
TH5
ADC3
VREF
ADC1
2.4V
5
DAC1
ADC2
5
DAC2
6
ENCODE
ENCODE
INTERNAL
TIMING
DIGITAL ERROR CORRECTION LOGIC
GND
DMID
OVR
DRY
D13
MSB
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
LSB
Figure 1.
Rev. D
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 that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2002–2008 Analog Devices, Inc. All rights reserved.
02647-001
AD6645
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Product Highlights ........................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
DC Specifications ......................................................................... 3
Digital Specifications ................................................................... 4
AC Specifications.......................................................................... 4
Switching Specifications .............................................................. 5
Absolute Maximum Ratings............................................................ 7
Thermal Resistance ...................................................................... 7
Explanation of Test Levels ............................................................7
ESD Caution...................................................................................7
Pin Configuration and Function Descriptions..............................8
Typical Performance Characteristics ..............................................9
Equivalent Circuits ......................................................................... 14
Terminology .................................................................................... 15
Theory of Operation ...................................................................... 17
Applying the AD6645 ................................................................ 17
Layout Information ........................................................................ 19
Jitter Considerations .................................................................. 19
Outline Dimensions ....................................................................... 24
Ordering Guide .......................................................................... 24
REVISION HISTORY
10/08—Rev. C to Rev. D
Added TQFP_EP Package ............................................ Throughout
Renamed Thermal Characteristics Section Thermal Resistance
Section ................................................................................................ 7
Added Table 6; Renumbered Sequentially .................................... 7
Moved Equivalent Circuits Section .............................................. 14
Moved Terminology Section ......................................................... 15
Changes to Table 9 .......................................................................... 20
Updated Outline Dimensions ....................................................... 24
Changes to Ordering Guide .......................................................... 24
12/06—Rev. B to Rev. C
Updated Format .................................................................. Universal
Changes to Specifications ................................................................ 3
Changes to Jitter Considerations Section .................................... 19
Changes to Table 8, Bill of Materials ............................................ 20
Changes to Figure 43, Evaluation Board Schematic .................. 21
Changes to Figure 44 and Figure 46 ............................................. 22
Updated Outline Dimensions ....................................................... 23
Changes to Ordering Guide .......................................................... 23
7/03—Rev. A to Rev. B.
Changes to Title ................................................................................1
Changes to Features ..........................................................................1
Changes to Product Description .....................................................1
Changes to Specifications .................................................................3
Changes to Absolute Maximum Ratings ........................................7
Changes to Ordering Guide .......................................................... 24
Updated Outline Dimensions ....................................................... 20
6/02—Rev. 0 to Rev. A.
Change to DC Specifications ...........................................................3
Rev. D | Page 2 of 24
AD6645
SPECIFICATIONS
DC SPECIFICATIONS
AV
CC
= 5 V, DV
CC
= 3.3 V; T
MIN
and T
MAX
at rated speed grade, unless otherwise noted.
Table 1.
Parameter
RESOLUTION
ACCURACY
No Missing Codes
Offset Error
Gain Error
Differential Nonlinearity (DNL)
Integral Nonlinearity (INL)
TEMPERATURE DRIFT
Offset Error
Gain Error
POWER SUPPLY REJECTION RATIO
(PSRR)
REFERENCE OUT (VREF)
1
ANALOG INPUTS (AIN, AIN)
Differential Input Voltage Range
Differential Input Resistance
Differential Input Capacitance
POWER SUPPLY
Supply Voltages
AV
CC
DV
CC
Supply Current
IAV
CC
(AV
CC
= 5.0 V)
IDV
CC
(DV
CC
= 3.3 V)
Rise Time
2
AV
CC
POWER CONSUMPTION
1
Temp
Test Level
AD6645ASQ-80/AD6645ASV-80
Min
Typ
Max
14
Guaranteed
+1.2
+10
0
+10
±0.25
+1.5
±0.5
1.5
48
±1.0
2.4
2.2
1
1.5
AD6645ASQ-105/AD6645ASV-105
Min
Typ
Max
14
Guaranteed
+1.2
+10
0
+10
±0.5
+1.5
±1.5
1.5
48
±1.0
2.4
2.2
1
1.5
Unit
Bits
Full
Full
Full
Full
Full
Full
Full
25°C
Full
Full
Full
25°C
II
II
II
II
V
V
V
V
V
V
V
−10
−10
−1.0
−10
−10
−1.0
mV
% FS
LSB
LSB
ppm/°C
ppm/°C
mV/V
V
V p-p
kΩ
pF
Full
Full
Full
Full
Full
Full
II
II
II
II
IV
II
4.75
3.0
5.0
3.3
275
32
5.25
3.6
320
45
250
1.75
4.75
3.0
5.0
3.3
275
32
5.0
1.5
5.25
3.6
320
45
250
1.75
V
V
mA
mA
ms
W
1.5
VREF is provided for setting the common-mode offset of a differential amplifier, such as the
AD8138,
when a dc-coupled analog input is required. VREF should be
buffered if used to drive additional circuit functions.
2
Specified for dc supplies with linear rise time characteristics.
Rev. D | Page 3 of 24
AD6645
DIGITAL SPECIFICATIONS
AV
CC
= 5 V, DV
CC
= 3.3 V; T
MIN
and T
MAX
at rated speed grade, unless otherwise noted.
Table 2.
Parameter
ENCODE INPUTS (ENCODE, ENCODE)
Differential Input Voltage
1
Differential Input Resistance
Differential Input Capacitance
LOGIC OUTPUTS (D13 to D0, DRY, OVR)
Logic Compatibility
Logic 1 Voltage (DV
CC
= 3.3 V)
2
Logic 0 Voltage (DV
CC
= 3.3 V)
2
Output Coding
DMID
1
2
Temp
Full
25°C
25°C
Test
Level
IV
V
V
AD6645ASQ-80/AD6645ASV-80
Min Typ
Max
0.4
10
2.5
CMOS
DV
CC
− 2
0.2
Twos complement
DV
CC
/2
AD6645ASQ-105/AD6645ASV-105
Min Typ
Max
0.4
10
2.5
CMOS
DV
CC
− 2
0.2
Twos complement
DV
CC
/2
Unit
V p-p
kΩ
pF
Full
Full
Full
II
II
V
2.85
2.85
0.5
0.5
V
V
V
All ac specifications tested by driving ENCODE and ENCODE differentially.
Digital output logic levels: DV
CC
= 3.3 V, C
LOAD
= 10 pF. Capacitive loads >10 pF degrades performance.
AC SPECIFICATIONS
All ac specifications tested by driving ENCODE and ENCODE differentially. AV
CC
= 5 V, DV
CC
= 3.3 V; ENCODE, ENCODE, T
MIN
and
T
MAX
at rated speed grade, unless otherwise noted.
Table 3.
Test
Level
V
II
I
II
V
V
V
II
I
V
V
V
V
II
I
V
V
V
AD6645ASQ-80/
AD6645ASV-80
Min
Typ
Max
75.0
74.5
73.5
73.0
72.0
75.0
74.5
72.5
73.0
68.5
62.5
93.0
93.0
85.0
89.0
70.0
63.5
72.5
72.0
AD6645ASQ-105/
AD6645ASV-105
Min
Typ
Max
75.0
74.5
73.5
73.0
72.0
75.0
74.5
73.0
67.5
62.5
93.1
93.0
87.0
70.0
63.5
Parameter
SNR
Analog Input @ −1 dBFS
Temp
25°C
Full
25°C
Full
25°C
25°C
25°C
Full
25°C
Full
25°C
25°C
25°C
Full
25°C
Full
25°C
25°C
Unit
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dBc
dBc
dBc
dBc
dBc
dBc
Conditions
At 15.5 MHz
At 30.5 MHz
At 37.7 MHz
At 70.0 MHz
At 150.0 MHz
At 200.0 MHz
At 15.5 MHz
At 30.5 MHz
At 37.7 MHz
At 70.0 MHz
At 150.0 MHz
At 200.0 MHz
At 15.5 MHz
At 30.5 MHz
At 37.7 MHz
At 70.0 MHz
At 150.0 MHz
At 200.0 MHz
72.5
72.0
SINAD
Analog Input @ −1 dBFS
72.5
WORST HARMONIC (SECOND OR THIRD)
Analog Input @ −1 dBFS
85.0
Rev. D | Page 4 of 24
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