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1
LTC1744
1744f
14-Bit, 50Msps ADC
s
Sample Rate: 50Msps
s
77dB SNR and 87dB SFDR (3.2V Range)
s
73.5dB SNR and 90dB SFDR (2V Range)
s
No Missing Codes
s
Single 5V Supply
s
Power Dissipation: 1.2W
s
Selectable Input Ranges:
1V or
1.6V
s
150MHz Full Power Bandwidth S/H
s
Pin Compatible Family
25Msps: LTC1746 (14 Bit), LTC1745 (12 Bit)
50Msps: LTC1744 (14 Bit), LTC1743 (12 Bit)
65Msps: LTC1742 (14 Bit), LTC1741 (12 Bit)
80Msps: LTC1748 (14 Bit), LTC1747 (12 Bit)
s
48-Pin TSSOP Package
s
Telecommunications
s
Receivers
s
Base Stations
s
Spectrum Analysis
s
Imaging Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
OF
14-BIT
PIPELINED ADC
14
S/H
CIRCUIT
1V
DIFFERENTIAL
ANALOG INPUT
A
IN
+
A
IN
SENSE
V
CM
4.7
F
DIFF AMP
REFLA
REFHB
GND
1744 BD
ENC
4.7
F
0.1
F
0.1
F
1
F
1
F
REFHA
REFLB
BUFFER
RANGE
SELECT
2.5V
REF
CORRECTION
LOGIC AND
SHIFT
REGISTER
OUTPUT
LATCHES
CONTROL LOGIC
OV
DD
V
DD
OGND
0.5V TO 5V
5V
0.1
F
1
F
1
F
1
F
D13
D0
CLKOUT
ENC
DIFFERENTIAL
ENCODE INPUT
OE
MSBINV
0.1
F
The LTC
1744 is a 50Msps, sampling 14-bit A/D con-
verter designed for digitizing high frequency, wide dynamic
range signals. Pin selectable input ranges of
1V and
1.6V
along with a resistor programmable mode allow the
LTC1744's input range to be optimized for a wide variety
of applications.
The LTC1744 is perfect for demanding communications
applications with AC performance that includes 77dB
SNR and 87dB spurious free dynamic range. Ultralow jitter
of 0.3ps
RMS
allows undersampling of IF frequencies with
excellent noise performance. DC specs include
4LSB
maximum INL and no missing codes over temperature.
The digital interface is compatible with 5V, 3V and 2V logic
systems. The ENC and ENC inputs may be driven differen-
tially from PECL, GTL and other low swing logic families or
from single-ended TTL or CMOS. The low noise, high gain
ENC and ENC inputs may also be driven by a sinusoidal
signal without degrading performance. A separate output
power supply can be operated from 0.5V to 5V, making it
easy to connect directly to any low voltage DSPs or FIFOs.
The TSSOP package with a flow-through pinout simplifies
the board layout.
50Msps, 14-Bit ADC with a
1V Differential Input Range
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
BLOCK DIAGRA
W
2
LTC1744
1744f
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution (No Missing Codes)
q
14
Bits
Integral Linearity Error
(Note 6)
q
4
1
4
LSB
Differential Linearity Error
q
1
0.5
1.5
LSB
Offset Error
(Note 7)
20
5
20
mV
Gain Error
External Reference (SENSE = 1.6V)
3
1
3
%FS
Full-Scale Tempco
I
OUT(REF)
= 0
40
ppm/
C
ORDER PART
NUMBER
OV
DD
= V
DD
(Notes 1, 2)
Supply Voltage (V
DD
) ................................................ 6V
Analog Input Voltage (Note 3) .... 0.3V to (V
DD
+ 0.3V)
Digital Input Voltage (Note 4) ..... 0.3V to (V
DD
+ 0.3V)
Digital Output Voltage ................. 0.3V to (V
DD
+ 0.3V)
OGND Voltage .............................................. 0.3V to 1V
Power Dissipation ............................................ 2000mW
Operating Temperature Range
LTC1744C ............................................... 0
C to 70
C
LTC1744I ............................................ 40
C to 85
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
LTC1744CFW
LTC1744IFW
T
JMAX
= 150
C,
JA
= 35
C/W
Consult factory for parts specified with wider operating temperature ranges.
The
q
indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Note 5)
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
TOP VIEW
FW PACKAGE
48-LEAD PLASTIC TSSOP
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
SENSE
V
CM
GND
A
IN
+
A
IN
GND
V
DD
V
DD
GND
REFLB
REFHA
GND
GND
REFLA
REFHB
GND
V
DD
V
DD
GND
V
DD
GND
MSBINV
ENC
ENC
OF
OGND
D13
D12
D11
OV
DD
D10
D9
D8
D7
OGND
GND
GND
D6
D5
D4
OV
DD
D3
D2
D1
D0
OGND
CLKOUT
OE
CO VERTER CHARACTERISTICS
U
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Analog Input Range (Note 8)
4.75V
V
DD
5.25V
q
1 to
1.6
V
I
IN
Analog Input Leakage Current
10
nA
C
IN
Analog Input Capacitance
Sample Mode ENC < ENC
15
pF
Hold Mode ENC > ENC
8
pF
t
ACQ
Sample-and-Hold Acquisition Time
q
7.5
9.5
ns
t
AP
Sample-and-Hold Acquisition Delay Time
0
ns
t
JITTER
Sample-and-Hold Acquisition Delay Time Jitter
0.3
ps
RMS
CMRR
Analog Input Common Mode Rejection Ratio
1.0V < (A
IN
= A
IN
+
) < 3.5V
80
dB
The
q
indicates specifications which apply over the full operating temperature range, otherwise
specifications are at T
A
= 25
C. (Note 5)
A ALOG I PUT
U
U
3
LTC1744
1744f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
SNR
Signal-to-Noise Ratio
5MHz Input Signal (2V Range)
73.5
dBFS
5MHz Input Signal (3.2V Range)
q
75.5
77
dBFS
25MHz Input Signal (2V Range)
72.5
dBFS
25MHz Input Signal (3.2V Range)
75.5
dBFS
70MHz Input Signal (2V Range)
70
dBFS
70MHz Input Signal (3.2V Range)
71.5
dBFS
SFDR
Spurious Free Dynamic Range
5MHz Input Signal (2V Range)
92
dB
5MHz Input Signal (3.2V Range)
q
76
87
dB
25MHz Input Signal (2V Range)
87
dB
25MHz Input Signal (3.2V Range)
79
dB
70MHz Input Signal (2V Range)
73
dB
70MHz Input Signal (3.2V Range)
66
dB
S/(N + D)
Signal-to-(Noise + Distortion) Ratio
5MHz Input Signal (2V Range)
73
dBFS
5MHz Input Signal (3.2V Range)
q
73
76
dBFS
25MHz Input Signal (2V Range)
72.5
dBFS
25MHz Input Signal (3.2V Range)
73.5
dBFS
70MHz Input Signal (2V Range)
68
dBFS
70MHz Input Signal (3.2V Range)
64
dBFS
THD
Total Harmonic Distortion
5MHz Input Signal, First 5 Harmonics (2V Range)
90
dB
5MHz Input Signal, First 5 Harmonics (3.2V Range)
85
dB
25MHz Input Signal, First 5 Harmonics (2V Range)
85
dB
25MHz Input Signal, First 5 Harmonics (3.2V Range)
78
dB
70MHz Input Signal, First 5 Harmonics (2V Range)
72
dB
70MHz Input Signal, First 5 Harmonics (3.2V Range)
65
dB
IMD
Intermodulation Distortion
f
IN1
= 2.52MHz, f
IN2
= 5.2MHz (2V Range)
90
dBc
f
IN1
= 2.52MHz, f
IN2
= 5.2MHz (3.2V Range)
80
dBc
Sample-and-Hold Bandwidth
R
SOURCE
= 50
150
MHz
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CM
Output Voltage
I
OUT
= 0
2.42
2.5
2.58
V
V
CM
Output Tempco
I
OUT
= 0
30
ppm/
C
V
CM
Line Regulation
4.75V
V
DD
5.25V
3
mV/V
V
CM
Output Resistance
1mA
I
OUT
1mA
4
The
q
indicates specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25
C. A
IN
= 1dBFS. (Note 5)
DY
A
IC ACCURACY
U
W
(Note 5)
I TER AL REFERE CE CHARACTERISTICS
U
U
U
4
LTC1744
1744f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
f
SAMPLE(MAX)
Maximum Sampling Frequency
q
50
MHz
t
1
ENC Low Time
(Note 9)
q
9.5
10
1000
ns
t
2
ENC High Time
(Note 9)
q
9.5
10
1000
ns
t
3
Aperture Delay of Sample-and-Hold
0
ns
t
4
ENC to Data Delay
C
L
= 10pF (Note 8)
q
1.4
4.5
8
ns
t
5
ENC to CLKOUT Delay
C
L
= 10pF (Note 8)
q
0.5
2.3
5
ns
t
6
CLKOUT to Data Delay
C
L
= 10pF (Note 8)
q
0
2.2
ns
t
7
DATA Access Time After OE
C
L
= 10pF (Note 8)
10
25
ns
t
8
BUS Relinquish Time
(Note 8)
10
25
ns
Data Latency
5
cycles
The
q
indicates specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25
C. (Note 5)
TI I G CHARACTERISTICS
U
W
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: All voltage values are with respect to ground with GND
(unless otherwise noted).
Note 3: When these pin voltages are taken below GND or above V
DD
, they
will be clamped by internal diodes. This product can handle input currents
of greater than 100mA below GND or above V
DD
without latchup.
Note 4: When these pin voltages are taken below GND, they will be
clamped by internal diodes. This product can handle input currents of
>100mA below GND without latchup. These pins are not clamped to V
DD
.
Note 5: V
DD
= 5V, f
SAMPLE
= 50MHz, differential ENC/ENC = 2V
P-P
50MHz
sine wave, input range =
1.6V differential, unless otherwise specified.
Note 6: Integral nonlinearity is defined as the deviation of a code from a
straight line passing through the actual endpoints of the transfer curve.
The deviation is measured from the center of the quantization band.
Note 7: Bipolar offset is the offset voltage measured from 0.5 LSB
when the output code flickers between 00 0000 0000 0000 and 11
1111 1111 1111.
Note 8: Guaranteed by design, not subject to test.
Note 9: Recommended operating conditions.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
DD
Positive Supply Voltage
4.75
5.25
V
I
DD
Positive Supply Current
q
245
300
mA
P
DIS
Power Dissipation
q
1.2
1.5
W
OV
DD
Digital Output Supply Voltage
0.5
V
DD
V
The
q
indicates specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25
C. (Note 5)
POWER REQUIRE E TS
W
U
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IH
High Level Input Voltage
V
DD
= 5.25V
q
2.4
V
V
IL
Low Level Input Voltage
V
DD
= 4.75V
q
0.8
V
I
IN
Digital Input Current
V
IN
= 0V to V
DD
q
10
A
C
IN
Digital Input Capacitance
MSBINV and OE Only
1.5
pF
V
OH
High Level Output Voltage
OV
DD
= 4.75V
I
O
= 10
A
4.74
V
I
O
= 200
A
q
4
V
V
OL
Low Level Output Voltage
OV
DD
= 4.75V
I
O
= 160
A
0.05
V
I
O
= 1.6mA
q
0.1
0.4
V
I
OZ
Hi-Z Output Leakage D13 to D0
V
OUT
= 0V to V
DD
, OE = High
q
10
A
C
OZ
Hi-Z Output Capacitance D13 to D0
OE = High (Note 8)
q
15
pF
I
SOURCE
Output Source Current
V
OUT
= 0V
50
mA
I
SINK
Output Sink Current
V
OUT
= 5V
50
mA
The
q
indicates specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25
C. (Note 5)
DIGITAL I PUTS A D DIGITAL OUTPUTS
U
U
5
LTC1744
1744f
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
CODE
0
4000
8000
12000
16000
INL ERROR (LSB)
1744 G01
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
T
A
= 25
C
CODE
0
4000
8000
12000
16000
DNL ERROR (LSB)
1744 G02
1.0
0.8
0.6
0.4
0.2
0
0.2
0.4
0.6
0.8
1.0
T
A
= 25
C
FREQUENCY (MHz)
0
25.37
AMPLITUDE (dBFS)
1744 G03
0.5
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
2
4
6
8 10 12 14 16 18 20 22 24
T
A
= 25
C
Typical INL, 3.2V Range
Typical DNL, 3.2V Range
Nonaveraged, 8192 Point FFT,
Input Frequency = 2.5MHz, 1dB,
2V Range
Nonaveraged, 8192 Point FFT,
Input Frequency = 20MHz, 1dB,
2V Range
Nonaveraged, 8192 Point FFT,
Input Frequency = 2.5MHz, 1dB,
3.2V Range
Nonaveraged, 8192 Point FFT,
Input Frequency = 20MHz, 1dB,
3.2V Range
FREQUENCY (MHz)
0
2
4
6
8 10 12 14 16 18 20 22 24
25.37
AMPLITUDE (dBFS)
1744 G04
0.5
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
T
A
= 25
C
FREQUENCY (MHz)
0
2
4
6
8 10 12 14 16 18 20 22 24
25.37
AMPLITUDE (dBFS)
1744 G05
0.5
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
T
A
= 25
C
FREQUENCY (MHz)
0
2
4
6
8 10 12 14 16 18 20 22 24
25.37
AMPLITUDE (dBFS)
1744 G06
0.5
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
T
A
= 25
C
Averaged, 8192 Point 2-Tone FFT,
Input Frequency = 2.5MHz and
5.2MHz, 2V Range
Averaged, 8192 Point 2-Tone FFT,
Input Frequency = 2.5MHz and
5.2MHz, 3.2V Range
FREQUENCY (MHz)
0
2
4
6
8 10 12 14 16 18 20 22 24
25.37
AMPLITUDE (dBFS)
1744 G07
0.5
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
T
A
= 25
C
FREQUENCY (MHz)
0
2
4
6
8 10 12 14 16 18 20 22 24
25.37
AMPLITUDE (dBFS)
1744 G08
0.5
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
T
A
= 25
C
(Note 5)
Averaged, 8192 Point FFT, Input
Frequency = 2.5MHz, 6dB,
2V Range
FREQUENCY (MHz)
0
2
4
6
8 10 12 14 16 18 20 22 24
25.37
AMPLITUDE (dBFS)
1744 G10
0.5
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
T
A
= 25
C
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