LTC1747
12-Bit, 80Msps Low Noise ADC
FEATURES
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DESCRIPTIO
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Sample Rate: 80Msps
72dB SNR and 85dB SFDR (3.2V Range)
70.5dB SNR and 87dB SFDR (2V Range)
Pin Compatible with 14-Bit 80Msps LTC1748
No Missing Codes
Single 5V Supply
Power Dissipation: 1.4W
Selectable Input Ranges:
±1V
or
±1.6V
240MHz Full Power Bandwidth S/H
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)
48-Pin TSSOP Package
The LTC
®
1747 is an 80Msps, sampling 12-bit A/D con-
verter designed for digitizing high frequency, wide dy-
namic range signals. Pin selectable input ranges of
±1V
and
±1.6V
along with a resistor programmable mode
allow the LTC1747’s input range to be optimized for a wide
variety of applications.
The LTC1747 is perfect for demanding communications
applications with AC performance that includes 72dB
SNR and 85dB spurious free dynamic range. Ultralow jitter
of 0.15ps
RMS
allows undersampling of IF frequencies with
excellent noise performance. DC specs include
±1.5
LSB
INL and
±0.8LSB
DNL over temperature.
The digital interface is compatible with 5V, 3V, 2V and
LVDS logic systems. The ENC and ENC inputs may be
driven differentially 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.
APPLICATIO S
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Telecommunications
Receivers
Cellular Base Stations
Spectrum Analysis
Imaging Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
BLOCK DIAGRA
A
IN+
±1V
DIFFERENTIAL
ANALOG INPUT
80Msps, 12-Bit ADC with a 2V Differential Input Range
OV
DD
0.1µF
OF
D11
D0
CLKOUT
0.5V
TO 5V
0.1µF
CORRECTION
LOGIC AND
SHIFT
REGISTER
12
A
IN–
S/H
AMP
12-BIT
PIPELINED ADC
SENSE
BUFFER
RANGE
SELECT
DIFF AMP
1µF
GND
CONTROL LOGIC
1747 BD
V
CM
4.7µF
2.35V
REF
REFLB
0.1µF
1µF
REFHA
4.7µF
REFLA
REFHB ENC
ENC
0.1µF
1µF
DIFFERENTIAL
ENCODE INPUT
U
OUTPUT
LATCHES
•
•
•
OGND
V
DD
1µF
5V
1µF
MSBINV
OE
W
U
1747fa
1
LTC1747
ABSOLUTE
MAXIMUM
RATINGS
OV
DD
= V
DD
(Notes 1, 2)
PACKAGE/ORDER INFORMATION
TOP VIEW
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
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
OF
OGND
D11
D10
D9
OV
DD
D8
D7
D6
D5
OGND
GND
GND
D4
D3
D2
OV
DD
D1
D0
NC
NC
OGND
CLKOUT
OE
Supply Voltage (V
DD
) ............................................. 5.5V
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
LTC1747C ............................................... 0°C to 70°C
LTC1747I ............................................ – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC1747CFW
LTC1747IFW
FW PACKAGE
48-LEAD PLASTIC TSSOP
T
JMAX
= 150°C,
θ
JA
= 35°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
CO VERTER CHARACTERISTICS
PARAMETER
Resolution (No Missing Codes)
Integral Linearity Error
Differential Linearity Error
Offset Error
Gain Error
Full-Scale Tempco
Offset Tempco
CONDITIONS
The
q
indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
q
(Note 6)
q
q
(Note 7)
External Reference (SENSE = 1.6V)
Internal Reference
External Reference (Sense = 1.6V)
MIN
12
–1
–1.5
–0.8
– 35
– 3.5
TYP
±0.4
±0.6
±0.2
±8
±1
±40
±20
±20
MAX
1
1.5
0.8
35
3.5
UNITS
Bits
LSB
LSB
LSB
mV
%FS
ppm/°C
ppm/°C
µV/°C
A ALOG I PUT
SYMBOL
V
IN
I
IN
C
IN
t
ACQ
t
AP
t
JITTER
CMRR
The
q
indicates specifications which apply over the full operating temperature range, otherwise
specifications are at T
A
= 25°C. (Note 5)
PARAMETER
Analog Input Range (Note 8)
Analog Input Leakage Current
Analog Input Capacitance
Sample-and-Hold Acquisition Time
Sample-and-Hold Acquisition Delay Time
Sample-and-Hold Acquisition Delay Time Jitter
Analog Input Common Mode Rejection Ratio
CONDITIONS
4.75V
≤
V
DD
≤
5.25V
Sample Mode ENC < ENC
Hold Mode ENC > ENC
q
MIN
q
q
TYP
±1
to
±1.6
8
4
5
0
0.15
80
MAX
1
–1
6
1.5V < (A
IN–
= A
IN+
) < 3V
UNITS
V
µA
pF
pF
ns
ns
ps
RMS
dB
1747fa
2
U
W
U
U
W W
W
U
U
U
LTC1747
DY A IC ACCURACY
SYMBOL
SNR
PARAMETER
Signal-to-Noise Ratio
SFDR
S/(N + D)
THD
IMD
I TER AL REFERE CE CHARACTERISTICS
PARAMETER
V
CM
Output Voltage
V
CM
Output Tempco
V
CM
Line Regulation
V
CM
Output Resistance
CONDITIONS
I
OUT
= 0
I
OUT
= 0
4.75V
≤
V
DD
≤
5.25V
1mA
≤ I
OUT
≤
1mA
U
W U
U
Specifications are at T
A
= 25°C. A
IN
= –1dBFS. (Note 5)
CONDITIONS
5MHz Input Signal (2V Range)
5MHz Input Signal (3.2V Range)
30MHz Input Signal (2V Range)
30MHz Input Signal (3.2V Range)
70MHz Input Signal (2V Range)
70MHz Input Signal (3.2V Range)
140MHz Input Signal (2V Range)
250MHz Input Signal (2V Range)
MIN
71
71
TYP
70.5
72
70.5
72
70
71.5
69.3
67.5
87
85
92
87
85
92
84
78
90
77
90
63
87
71
70.5
72
70.5
72
70
71.5
–85
–84
–85
–84
–81
–77
87
85
240
MAX
UNITS
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
dBc
dBc
MHz
Spurious Free Dynamic Range
5MHz Input Signal (2V Range)
5MHz Input Signal (3.2V Range) (2nd and 3rd)
5MHz Input Signal (3.2V Range) (Other)
30MHz Input Signal (2V Range)
30MHz Input Signal (3.2V Range) (2nd and 3rd)
30MHz Input Signal (3.2V Range) (Other)
70MHz Input Signal (2V Range)
70MHz Input Signal (3.2V Range) (2nd and 3rd)
70MHz Input Signal (3.2V Range) (Other)
140MHz Input Signal (2V Range) (2nd and 3rd)
140MHz Input Signal (2V Range) (Other)
250MHz Input Signal (2V Range) (2nd and 3rd)
250MHz Input Signal (2V Range) (Other)
84
77
84
84
Signal-to-(Noise + Distortion) Ratio
5MHz Input Signal (2V Range)
5MHz Input Signal (3.2V Range)
30MHz Input Signal (2V Range)
30MHz Input Signal (3.2V Range)
70MHz Input Signal (2V Range)
70MHz Input Signal (3.2V Range)
Total Harmonic Distortion
5MHz Input Signal, First 5 Harmonics (2V Range)
5MHz Input Signal, First 5 Harmonics (3.2V Range)
30MHz Input Signal, First 5 Harmonics (2V Range)
30MHz Input Signal, First 5 Harmonics (3.2V Range)
70MHz Input Signal, First 5 Harmonics (2V Range)
70MHz Input Signal, First 5 Harmonics (3.2V Range)
Intermodulation Distortion
Sample-and-Hold Bandwidth
f
IN1
= 2.52MHz, f
IN2
= 5.2MHz (2V Range)
f
IN1
= 2.52MHz, f
IN2
= 5.2MHz (3.2V Range)
R
SOURCE
= 50Ω
U
(Note 5)
MIN
2.30
TYP
2.35
±30
3
4
MAX
2.40
UNITS
V
ppm/°C
mV/V
Ω
1747fa
3
LTC1747
DIGITAL I PUTS A D DIGITAL OUTPUTS
SYMBOL
V
IH
V
IL
I
IN
C
IN
V
OH
V
OL
I
OZ
C
OZ
I
SOURCE
I
SINK
PARAMETER
High Level Input Voltage
Low Level Input Voltage
Digital Input Current
Digital Input Capacitance
High Level Output Voltage
Low Level Output Voltage
Hi-Z Output Leakage D11 to D0
Hi-Z Output Capacitance D11 to D0
Output Source Current
Output Sink Current
CONDITIONS
V
DD
= 5.25V
V
DD
= 4.75V
V
IN
= 0V to V
DD
MSBINV and OE Only
OV
DD
= 4.75V
OV
DD
= 4.75V
V
OUT
= 0V to V
DD
, OE = High
OE = High (Note 8)
V
OUT
= 0V
V
OUT
= 5V
I
O
= –10µA
I
O
= – 200µA
I
O
= 160µA
I
O
= 1.6mA
q
q
q
q
q
q
q
The
q
indicates specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 5)
MIN
2.4
0.8
±10
1.5
4.74
4
4.74
0.05
0.1
0.4
±10
15
– 50
50
TYP
MAX
UNITS
V
V
µA
pF
V
V
V
V
µA
pF
mA
mA
POWER REQUIRE E TS
SYMBOL
V
DD
I
DD
P
DIS
OV
DD
PARAMETER
Positive Supply Voltage
Positive Supply Current
Power Dissipation
Digital Output Supply Voltage
The
q
indicates specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 5)
CONDITIONS
q
q
TI I G CHARACTERISTICS
SYMBOL
t
0
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
8
t
9
t
10
t
11
t
12
PARAMETER
ENC Period
ENC High
ENC Low
Aperture Delay
ENC to CLKOUT Falling
ENC to CLKOUT Rising
For 80Msps 50% Duty Cycle
ENC to DATA Delay
ENC to DATA Delay (Hold Time)
ENC to DATA Delay (Setup Time)
For 80Msps 50% Duty Cycle
CLKOUT to DATA Delay (Hold Time),
80Msps 50% Duty Cycle
CLKOUT to DATA Delay (Setup Time),
80Msps 50% Duty Cycle
DATA Access Time After OE
BUS Relinquish
Data Latency
The
q
indicates specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 5)
CONDITIONS
(Note 9)
(Note 8)
(Note 8)
(Note 8)
C
L
= 10pF (Note 8)
C
L
= 10pF (Note 8)
C
L
= 10pF (Note 8)
C
L
= 10pF (Note 8)
(Note 8)
C
L
= 10pF (Note 8)
C
L
= 10pF (Note 8)
(Note 8)
C
L
= 10pF (Note 8)
C
L
= 10pF (Note 8)
(Note 8)
q
q
q
5.3
6
2.1
10
10
5
25
25
q
q
q
7.25
2
1.4
q
1
q
4
U W
U
U
MIN
4.75
TYP
280
1.4
MAX
5.25
310
1.55
V
DD
UNITS
V
mA
W
V
0.5
UW
MIN
12.5
6
6
q
q
TYP
MAX
2000
1000
1000
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
cycles
1747fa
0
2.4
t
1
+ t
4
8.65
4.9
3.4
t
0
– t
6
7.6
10.5
10.25
7.2
4.7
4
LTC1747
ELECTRICAL CHARACTERISTICS
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 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
= 80MHz, differential ENC/ENC = 2V
P-P
80MHz
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 0000 0000 0000 and
1111 1111 1111.
Note 8:
Guaranteed by design, not subject to test.
Note 9:
Recommended operating conditions.
TYPICAL PERFOR A CE CHARACTERISTICS
INL, 3.2V Range
1
0.8
0.6
T
A
= 25°C
DNL ERROR (LSB)
INL ERROR (LSB)
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0
1024
2048
3072
OUTPUT CODE
4096
1747 G01
Averaged 8192 Point FFT,
5.2MHz Input, –1dB, 3.2V Range
0
–10
–20
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
–50
–60
–70
–80
–90
–100
–110
–120
0
5
10
15 20 25 30
FREQUENCY (MHz)
35
40
–50
–60
–70
–80
–90
–100
–110
–120
0
5
10
15 20 25 30
FREQUENCY (MHz)
35
40
AMPLITUDE (dBFS)
–30
–40
U W
T
A
= 25°C
1747 G04
DNL, 3.2V Range
1
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0
1024
3072
2048
OUTPUT CODE
4096
1747 G02
T
A
= 25°C
Averaged 8192 Point FFT,
5.2MHz Input, –10dB, 3.2V Range
0
–10
–20
–30
–40
T
A
= 25°C
Averaged 8192 Point FFT,
5.2MHz Input, –20dB, 3.2V Range
0
T
A
= 25°C
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
0
5
10
15 20 25 30
FREQUENCY (MHz)
35
40
1747 G05
1747 G06
1747fa
5
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