19-3077; Rev 2; 8/08
1.8V, 8-Bit, 250Msps Analog-to-Digital Converter
with LVDS Outputs for Wideband Applications
General Description
The MAX1121 is a monolithic 8-bit, 250Msps analog-to-
digital converter (ADC) optimized for outstanding
dynamic performance at high IF frequencies up to
500MHz. The product operates with conversion rates of
up to 250Msps while consuming only 477mW.
At 250Msps and an input frequency of 100MHz, the
MAX1121 achieves a spurious-free dynamic range
(SFDR) of 68dBc. Its excellent signal-to-noise ratio
(SNR) of 48.9dB at 10MHz remains flat (within 0.5dB)
for input tones up to 500MHz. This makes the MAX1121
ideal for wideband applications such as digital predis-
tortion in cellular base-station transceiver systems.
The MAX1121 requires a single 1.8V supply. The ana-
log input is designed for either differential or single-
ended operation and can be AC- or DC-coupled. The
ADC also features a selectable on-chip divide-by-2
clock circuit, which allows the user to apply clock fre-
quencies as high as 500MHz. This helps to reduce the
phase noise of the input clock source. A differential
LVDS sampling clock is recommended for best perfor-
mance. The converter’s digital outputs are LVDS com-
patible, and the data format can be selected to be
either two’s complement or offset binary.
The MAX1121 is available in a 68-pin QFN with
exposed pad (EP) and is specified over the industrial
(-40°C to +85°C) temperature range.
For pin-compatible, higher resolution versions of the
MAX1121, refer to the MAX1122 (170Msps), the
MAX1123 (210Msps), and the MAX1124 (250Msps)
data sheets.
♦
250Msps Conversion Rate
♦
SNR = 48.8dB/48.7dB at f
IN
= 100MHz/500MHz
♦
SFDR = 68dBc/63.8dBc at f
IN
= 100MHz/500MHz
♦
Single 1.8V Supply
♦
477mW Power Dissipation at 250Msps
♦
On-Chip Track-and-Hold and Internal Reference
♦
On-Chip Selectable Divide-by-2 Clock Input
♦
LVDS Digital Outputs with Data Clock Output
♦
Evaluation Kit Available (Order MAX1124EVKIT)
Features
MAX1121
Ordering Information
PART
MAX1121EGK
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
68 QFN-EP*
*EP
= Exposed pad.
Pin Configuration
TOP VIEW
OGND
AGND
AGND
AGND
AV
CC
OV
CC
AV
CC
AV
CC
ORN
ORP
D7N
D6N
D5N
51
D4P
50
D4N
49
D3P
48
D3N
47
D2P
46
D2N
45
OGND
44
OV
CC
43
DCLKP
42
DCLKN
41
OV
CC
40
D1P
39
D1N
38
D0P
37
D0N
36
N.C.
35
N.C.
D7P
D6P
N.C.
Applications
Wireless and Wired Broadband Communication
Digital Oscilloscopes
Digital Predistortion Receivers
Communications Test Equipment
Radar and Satellite Subsystems Antenna Array
Processing
Instrumentation
AV
CC
AGND
REFIO
REFADJ
AGND
AV
CC
AGND
INP
INN
1
2
3
4
5
6
7
8
9
68
67 66 65 64
63 62 61 60 59 58
57 56 55 54 53 52
EP
MAX1121
AGND
10
AV
CC
11
AV
CC
12
AV
CC
13
AV
CC
14
AGND
15
AGND
16
CLKDIV
17
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
AGND
AV
CC
OV
CC
OV
CC
N.C.
N.C.
N.C.
D5P
T/B
CLKP
CLKN
AV
CC
OGND
AGND
PART
MAX1121EGK
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
68 QFN-EP*
________________________________________________________________
Maxim Integrated Products
AGND
AGND
N.C.
N.C.
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1.8V, 8-Bit, 250Msps Analog-to-Digital Converter
with LVDS Outputs for Wideband Applications
MAX1121
ABSOLUTE MAXIMUM RATINGS
AV
CC
to AGND ......................................................-0.3V to +2.1V
OV
CC
to OGND .....................................................-0.3V to +2.1V
AV
CC
to OV
CC
.......................................................-0.3V to +2.1V
AGND to OGND ....................................................-0.3V to +0.3V
Analog Inputs to AGND ...........................-0.3V to (AV
CC
+ 0.3V)
Digital Inputs to AGND.............................-0.3V to (AV
CC
+ 0.3V)
REF, REFADJ to AGND............................-0.3V to (AV
CC
+ 0.3V)
Digital Outputs to OGND .........................-0.3V to (OV
CC
+ 0.3V)
ESD on All Pins (Human Body Model).............................±2000V
Continuous Power Dissipation (T
A
= +70°C)
68-Pin QFN (derate 41.7mW/°C above +70°C) .........3333mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Maximum Current into Any Pin............................................50mA
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(AV
CC
= OV
CC
= 1.8V, V
AGND
= V
OGND
= 0, f
SAMPLE
= 250MHz, differential sine-wave clock input drive, 0.1µF capacitor on REFIO,
internal reference, digital output pins differential R
L
= 100Ω ±1%, C
L
= 5pF, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
≥
+25°C
guaranteed by production test, < +25°C guaranteed by design and characterization. Typical values are at T
A
= +25°C.)
PARAMETER
DC ACCURACY
Resolution
Integral Nonlinearity
Differential Nonlinearity
Transfer Curve Offset
Offset Temperature Drift
ANALOG INPUTS (INP, INN)
Full-Scale Input Voltage Range
Full-Scale Range Temperature
Drift
Common-Mode Input Range
Input Capacitance
Differential Input Resistance
Full-Power Analog Bandwidth
REFERENCE (REFIO, REFADJ)
Reference Output Voltage
Reference Temperature Drift
REFADJ Input High Voltage
SAMPLING CHARACTERISTICS
Maximum Sampling Rate
Minimum Sampling Rate
f
SAMPLE
f
SAMPLE
250
20
MHz
MHz
V
REFADJ
Used to disable the internal reference
AV
CC
-
0.3
V
REFIO
1.18
1.24
90
1.30
V
ppm/°C
V
V
CM
C
IN
R
IN
FPBW
Figure 8
3.00
V
FS
(Note 1)
1100
1250
130
1.38
±0.18
3
4.4
600
6.5
1375
mV
P-P
ppm/°C
V
pF
k
MHz
INL
DNL
V
OS
(Note 1)
No missing codes (Note 1)
(Note 1)
8
-0.6
-0.9
-10
±20
±0.2
±0.1
+0.6
+0.9
+10
Bits
LSB
LSB
LSB
μV/°C
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
1.8V, 8-Bit, 250Msps Analog-to-Digital Converter
with LVDS Outputs for Wideband Applications
ELECTRICAL CHARACTERISTICS (continued)
(AV
CC
= OV
CC
= 1.8V, V
AGND
= V
OGND
= 0, f
SAMPLE
= 250MHz, differential sine-wave clock input drive, 0.1µF capacitor on REFIO,
internal reference, digital output pins differential R
L
= 100Ω ±1%, C
L
= 5pF, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
≥
+25°C
guaranteed by production test, < +25°C guaranteed by design and characterization. Typical values are at T
A
= +25°C.)
PARAMETER
Clock Duty Cycle
Aperture Delay
Aperture Jitter
CLOCK INPUTS (CLKP, CLKN)
Differential Clock Input
Clock Input Common-Mode
Voltage Range
Clock Differential Input
Resistance
Clock Differential Input
Capacitance
R
CLK
C
CLK
(Note 2)
200
500
1.25
±0.25
11
±25%
5
mV
P-P
V
k
pF
t
AD
t
AJ
SYMBOL
CONDITIONS
Set by clock management circuit
MIN
TYP
40 to 60
350
0.2
MAX
UNITS
%
ps
ps
RMS
MAX1121
DYNAMIC CHARACTERISTICS (at -0.5dBFS)
f
IN
= 10MHz, T
A
Signal-to-Noise Ratio
SNR
f
IN
= 100MHz, T
A
f
IN
= 180MHz
f
IN
= 500MHz
Signal-to-Noise
and Distortion
f
IN
= 10MHz, T
A
+25°C
f
IN
= 100MHz, T
A
+25°C
f
IN
= 180MHz
f
IN
= 500MHz
f
IN
= 10MHz, T
A
Spurious-Free
Dynamic Range
SFDR
f
IN
= 100MHz, T
A
f
IN
= 180MHz
f
IN
= 500MHz
f
IN
= 10MHz
Worst Harmonics
(HD2 or HD3)
f
IN
= 100MHz
f
IN
= 180MHz
f
IN
= 500MHz
Two-Tone Intermodulation
Distortion
IMD
100
IMD
500
f
IN1
= 99MHz at -7dBFS,
f
IN2
= 101MHz at -7dBFS
f
IN1
= 498.5MHz at -7dBFS,
f
IN2
= 502.5MHz at -7dBFS
250
+25°C
+25°C
60
59
47.1
46.1
+25°C
+25°C
47.2
46.2
48.9
48.8
48.8
48.7
48.8
48.7
48.7
48.6
69
68
69.1
63.8
-74.6
-68.4
-69.1
-63.8
-70
dBc
-56
dBc
dBc
dB
dB
SINAD
LVDS DIGITAL OUTPUTS (D0P/N–D7P/N, ORP/N)
Differential Output Voltage
|V
OD
|
450
mV
_______________________________________________________________________________________
3
1.8V, 8-Bit, 250Msps Analog-to-Digital Converter
with LVDS Outputs for Wideband Applications
MAX1121
ELECTRICAL CHARACTERISTICS (continued)
(AV
CC
= OV
CC
= 1.8V, V
AGND
= V
OGND
= 0, f
SAMPLE
= 250MHz, differential sine-wave clock input drive, 0.1µF capacitor on REFIO,
internal reference, digital output pins differential R
L
= 100Ω ±1%, C
L
= 5pF, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
≥
+25°C
guaranteed by production test, < +25°C guaranteed by design and characterization. Typical values are at T
A
= +25°C.)
PARAMETER
Output Offset Voltage
SYMBOL
OV
OS
CONDITIONS
MIN
1.125
TYP
MAX
1.310
0.2 x
AV
CC
0.8 x
AV
CC
Figure 4
Figure 4
Figure 4 (Note 2)
20% to 80%, C
L
= 5pF
20% to 80%, C
L
= 5pF
0.92
1.5
2.85
1.35
460
460
8
1.86
UNITS
V
LVCMOS DIGITAL INPUTS (CLKDIV,
T/B)
Digital Input Voltage Low
Digital Input Voltage High
TIMING CHARACTERISTICS
CLK to Data Propagation Delay
CLK to DCLK Propagation Delay
Data Valid to DCLK Rising Edge
LVDS Output Rise-Time
LVDS Output Fall-Time
Output Data Pipeline Delay
POWER REQUIREMENTS
Analog Supply Voltage Range
Digital Supply Voltage Range
Analog Supply Current
Digital Supply Current
Total Power Dissipation
Power-Supply Rejection Ratio
(Note 3)
AV
CC
OV
CC
I
AVCC
I
OVCC
P
DISS
PSRR
f
IN
= 100MHz
f
IN
= 100MHz
f
IN
= 100MHz
Offset
Gain
1.70
1.70
1.80
1.80
220
45
477
1.6
1.9
1.90
1.90
290
75
657
V
V
mA
mA
mW
mV/V
%FS/V
t
PDL
t
CPDL
t
CPDL
-
t
PDL
t
RISE
t
FALL
t
LATENCY
ns
ns
ns
ps
ps
Clock
cycles
V
IL
V
IH
V
V
Note 1:
Static linearity and offset parameters are computed from a best-fit straight line through the code transition points. The full-
scale range is defined as 1023 x slope of the line.
Note 2:
Parameter guaranteed by design and characterization; T
A
= T
MIN
to T
MAX
.
Note 3:
PSRR is measured with both analog and digital supplies connected to the same potential.
4
_______________________________________________________________________________________
1.8V, 8-Bit, 250Msps Analog-to-Digital Converter
with LVDS Outputs for Wideband Applications
Typical Operating Characteristics
(AV
CC
= OV
CC
= 1.8V, V
AGND
= V
OGND
= 0, f
SAMPLE
= 250.0057MHz, -0.5dBFS; see TOCs for detailed information on test condi-
tions, differential input drive, differential sine-wave clock input drive, 0.1µF capacitor on REFIO, internal reference, digital output pins
differential R
L
= 100Ω, T
A
= +25°C.)
FFT PLOT (8192-POINT DATA RECORD,
COHERENT SAMPLING)
MAX1121 toc01
MAX1121
FFT PLOT (8192-POINT DATA RECORD,
COHERENT SAMPLING)
MAX1121 toc02
FFT PLOT (8192-POINT DATA RECORD,
COHERENT SAMPLING)
-10
-20
AMPLITUDE (dB)
-30
-40
-50
-60
-70
-80
-90
HD3
HD2
f
SAMPLE
= 250.0057MHz
f
IN
= 183.5064MHz
A
IN
= -0.5245MHz
SNR = 48.8dB
SFDR = 69.1dBc
HD2 = -77.2dBc
HD3 = -69.1dBc
MAX1121 toc03
0
-10
-20
AMPLITUDE (dB)
-30
-40
-50
-60
-70
-80
-90
0
20
40
60
80
100
120
HD2 HD3
f
SAMPLE
= 250.0057MHz
f
IN
= 11.5054MHz
A
IN
= -0.4885MHz
SNR = 48.9dB
SFDR = 71.5dBc
HD2 = -79.2dBc
HD3 = -74.6dBc
0
-10
-20
AMPLITUDE (dB)
-30
-40
-50
-60
-70
-80
-90
HD3
HD2
f
SAMPLE
= 250.0057MHz
f
IN
= 60.0294MHz
A
IN
= -0.4885MHz
SNR = 49dB
SFDR = 71.1dBc
HD2 = -79.5dBc
HD3 = -71.9dBc
0
140
0
20
40
60
80
100
120
140
0
20
40
60
80
100
120
140
ANALOG INPUT FREQUENCY (MHz)
ANALOG INPUT FREQUENCY (MHz)
ANALOG INPUT FREQUENCY (MHz)
FFT PLOT (8192-POINT DATA RECORD,
COHERENT SAMPLING)
-10
-20
AMPLITUDE (dB)
-30
-40
-50
-60
-70
-80
-90
0
20
40
60
80 100 120
ANALOG INPUT FREQUENCY (MHz)
140
45
HD2
46
HD3
FUNDAMENTAL
f
SAMLE
= 250.0057MHz
f
IN
= 500.516MHz
A
IN
= -0.5235MHz
SNR = 48.8dB
SFDR = 63.8dBc
HD2 = -70.8dBc
HD3 = -63.8dBc
MAX1121 toc04
SNR vs. ANALOG INPUT FREQUENCY
(f
SAMPLE
= 250.0057MHz, A
IN
= -0.5dBFS)
MAX1121 toc05
SFDR vs. ANALOG INPUT FREQUENCY
(f
SAMPLE
= 250.0057MHz, A
IN
= -0.5dBFS)
MAX1121 toc06
0
50
80
49
74
SFDR (dBc)
SNR (dB)
48
68
47
62
56
50
0
100
200
300
400
500
0
100
200
300
400
500
f
IN
(MHz)
f
IN
(MHz)
HD2/HD3 vs. ANALOG INPUT FREQUENCY
(f
SAMPLE
= 250.0057MHz, A
IN
= -0.5dBFS)
MAX1121 toc07
SNR vs. ANALOG INPUT AMPLITUDE
(f
SAMPLE
= 250.0057MHz, f
IN
= 60.0294MHz)
MAX1121 toc08
SFDR vs. ANALOG INPUT AMPLITUDE
(f
SAMPLE
= 250.0057MHz, f
IN
= 60.0294MHz)
70
65
MAX1121 toc09
-50
50
45
40
SNR (dB)
75
-60
HD2/HD3 (dBc)
HD3
60
SFDR (dBc)
55
50
45
40
-70
35
30
25
-80
HD2
-90
35
-100
0
100
200
300
400
500
f
IN
(MHz)
20
-30
-25
-20
-15
-10
-5
0
ANALOG INPUT AMPLITUDE (dBFS)
30
-30
-25
-20
-15
-10
-5
0
ANALOG INPUT AMPLITUDE (dBFS)
_______________________________________________________________________________________
5
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