19-1335; Rev 0a; 2/98
KIT
ATION
EVALU
BLE
AVAILA
Low-Power, 90Msps, 6-Bit ADC
General Description
Features
o
High Sampling Rate: 90Msps
o
Low Power Dissipation: 215mW
o
Excellent Dynamic Performance:
5.85 ENOB with 20MHz Analog Input
5.7 ENOB with 50MHz Analog Input
o
±1/4LSB INL and DNL (typ)
o
±1/4LSB Input Offset (typ)
o
Internal Bandgap Voltage Reference
o
Internal Oscillator with Overdrive Capability
o
55MHz (-0.5dB) Bandwidth Input Amplifier with
True Differential Input
o
User-Selectable Full-Scale Range
(125mVp-p, 250mVp-p, or 500mVp-p)
o
Single-Ended or Differential Input Drive
o
Flexible, 3.3V, CMOS-Compatible Digital Outputs
MAX1011
The MAX1011 is a 6-bit analog-to-digital converter
(ADC) that combines high-speed, low-power operation
with a user-selectable input range, an internal refer-
ence, and a clock oscillator. The ADC converts analog
signals into binary-coded digital outputs at sampling
rates up to 90Msps. The ability to directly interface with
baseband signals makes the MAX1011 ideal for use in
a wide range of communications and instrumentation
applications.
The MAX1011’s input amplifier features a true differential
input, a -0.5dB analog bandwidth of 55MHz, and a user-
programmable input full-scale range of 125mVp-p,
250mVp-p, or 500mVp-p. With an AC-coupled signal,
input offset is typically less than 1/4LSB. Dynamic per-
formance is 5.85 effective number of bits (ENOB) with a
20MHz analog input signal, or 5.7 ENOB with a 50MHz
signal.
The MAX1011 operates with +5V analog and +3.3V digi-
tal supplies for easy interfacing to +3.3V-logic-compatible
digital signal processors and microprocessors. It comes
in a 24-pin QSOP package.
Applications
IF Sampling Receivers
VSAT Receivers
Wide Local Area Networks (WLANs)
Instrumentation
PART
MAX1011CEG
Ordering Information
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
24 QSOP
Pin Configuration appears at end of data sheet.
Functional Diagram
OCC+
IN+
INPUT
AMP
OCC-
ADC
VREF
OFFSET
CORREC-
TION
6
IN-
DATA
BUFFER
6
D0–D5
CLOCK
OUT
BANDGAP
REFERENCE
CLOCK
DRIVER
DCLK
TNK+
TNK-
GAIN
MAX1011
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
For small orders, phone 408-737-7600 ext. 3468.
Low-Power, 90Msps, 6-Bit ADC
MAX1011
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND ..........................................................-0.3V to +6.5V
V
CCO
to OGND......................................................-0.3V to +6.5V
GND to OGND ......................................................-0.3V to +0.3V
Digital and Clock Output Pins to OGND...-0.3V to V
CCO
(10sec)
All Other Pins to GND...............................................-0.3V to V
CC
Continuous Power Dissipation (T
A
= +70°C)
24-Pin QSOP (derate 10mW/°C above +70°C)...........800mW
Operating Temperature Range...............................0°C to +70°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, <10sec)...........................+300°C
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.
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +5V ±5%, V
CCO
= 3.3V ±300mV,
T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
DC ACCURACY
(Note 1)
Resolution
Integral Nonlinearity
Differential Nonlinearity
Full-Scale Input Range
RES
INL
DNL
V
FSH
V
FSM
V
FSL
Input Open-Circuit Voltage
Input Resistance
Input Capacitance
Common-Mode Voltage Range
OSCILLATOR INPUTS
Oscillator Input Resistance
DIGITAL OUTPUTS (D0–D5)
Digital Outputs Logic-High
Voltage
Digital Outputs Logic-Low
Voltage
POWER SUPPLY
Supply Current
Power-Supply Rejection Ratio
Digital Outputs Supply Current
Power Dissipation
I
CC
PSRR
I
CCO
PD
V
CC
= 4.75V to 5.25V (Note 3)
20MHz, full-scale analog inputs,
C
L
= 15pF (Note 4)
37
-65
8.5
215
63.5
-40
13.8
mA
dB
mA
mW
V
OH
V
OL
I
SOURCE
= 50µA
I
SINK
= 400µA
0.7V
CCO
0.5
V
V
R
OSC
Other oscillator input tied to V
CC
+ 0.3V
4.8
8
12.1
kΩ
V
AOC
R
IN
C
IN
V
CM
Guaranteed by design
Other analog input driven with external source
(Note 2)
1.75
No missing codes over temperature
GAIN = V
CC
(high gain)
GAIN = open (mid gain)
GAIN = GND (low gain)
6
-0.5
-0.5
118.75
237.5
475
2.25
13
±0.25
±0.25
125
250
500
2.35
20
1.5
0.5
0.5
131.25
262.5
525
2.45
29
3
2.75
V
kΩ
pF
V
mVp-p
Bits
LSB
LSB
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
INVERTING AND NONINVERTING ANALOG INPUTS
2
_______________________________________________________________________________________
Low-Power, 90Msps, 6-Bit ADC
AC ELECTRICAL CHARACTERISTICS
(V
CC
= +5V ±5%, V
CCO
= 3.3V ±300mV,
T
A
= +25°C,
unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1011
DYNAMIC PERFORMANCE
(Gain = open, external 90MHz clock (Figure 7), V
IN
= 20MHz sine, amplitude -1dB below
full scale, unless otherwise noted.)
Maximum Sample Rate
Analog Input -0.5dB Bandwidth
f
MAX
BW
ENOB
M
Effective Number of Bits
ENOB
H
ENOB
L
Signal-to-Noise Plus Distortion
Ratio
Input Offset (Note 5)
Clock to Data Propagation
Delay
Data Valid Skew
Input to DCLK Delay
Aperture Delay
Pipeline Delay
SINAD
OFF
GAIN = GND, open, V
CC
GAIN = open (mid gain)
GAIN = open (mid gain), f
IN
= 50MHz,
-1dB below full scale
GAIN = V
CC
(high gain)
GAIN = GND (low gain)
GAIN = open (mid gain)
Guaranteed by design
35.5
-0.5
5.6
90
55
5.85
5.7
5.8
5.85
37
0.5
dB
LSB
Bits
Msps
MHz
TIMING CHARACTERISTICS
(Data outputs: R
L
= 1MΩ, C
L
= 15pF)
t
PD
t
SKEW
t
DCLK
t
AD
PD
(Note 6)
(Note 6)
TNK+ to DCLK (Note 6)
Figure 8
Figure 8
3.0
1
4.5
5.5
1
ns
ns
ns
ns
clock
cycle
Note 1:
Best-fit straight-line linearity method.
Note 2:
A typical application will AC couple the analog input to the DC bias level present at the analog inputs (typically 2.35V).
However, it is also possible to DC couple the analog input (using differential or single-ended drive) within this common-
mode input range (Figures 4 and 5).
Note 3:
PSRR is defined as the change in the mid-gain, full-scale range as a function of the variation in V
CC
supply voltage,
expressed in decibels.
Note 4:
The current in the V
CCO
supply is a strong function of the capacitive loading on the digital outputs. To minimize supply tran-
sients and achieve optimal dynamic performance, reduce the capacitive-loading effects by keeping line lengths on the dig-
ital outputs to a minimum.
Note 5:
Offset-correction compensation enabled, 0.22µF at compensation inputs (Figures 2 and 3).
Note 6:
t
PD
and t
SKEW
are measured from the 1.4V level of the output clock, to the 1.4V level of either the rising or falling edge of a
data bit. t
DCLK
is measured from the 50% level of the clock-overdrive signal on TNK+ to the 1.4V level of DCLK. The capac-
itive load on the outputs is 15pF.
_______________________________________________________________________________________
3
Low-Power, 90Msps, 6-Bit ADC
MAX1011
__________________________________________Typical Operating Characteristics
(V
CC
= +5V ±5%, V
CCO
= 3.3V ±300mV, f
CLK
= 90Msps, GAIN = open (midgain) MAX1011 evaluation kit, T
A
= +25°C, unless
otherwise noted.)
EFFECTIVE NUMBER OF BITS
vs. ANALOG INPUT FREQUENCY
MAX1011-01
ANALOG INPUT BANDWIDTH
0
-0.2
MAGNITUDE (dB)
MAX1011-02
EFFECTIVE NUMBER OF BITS
vs. SAMPLING/CLOCK FREQUENCY
MAX1011-03
6.0
6.0
EFFECTIVE NUMBER OF BITS
EFFECTIVE NUMBER OF BITS
5.8
5.9
5.6
5.8
-0.4
-0.6
-0.8
5.4
5.7
5.2
f
CLK
= 90Msps
5.0
10
ANALOG INPUT FREQUENCY (MHz)
100
5.6
f
IN
= 20MHz
-1.0
1
10
ANALOG INPUT FREQUENCY (MHz)
100
5.5
1
10
CLOCK FREQUENCY (MHz)
100
OSCILLATOR OPEN-LOOP PHASE NOISE
vs. FREQUENCY OFFSET
MAX1011-04
FFT PLOT
f
IN
= 19.9512MHz
f
CLK
= 90.000MHz
1024 POINTS
AC-COUPLED
SINGLE-ENDED
AVERAGED
MAX1011-05
-50
0
-70
PHASE NOISE (dBc)
AMPLITUDE (dB)
1k
10k
100k
1M
-20
-90
-40
-110
-60
-130
-80
0
9
18
27
36
45
FREQUENCY OFFSET FROM CARRIER (Hz)
FREQUENCY (MHz)
INTEGRAL NONLINEARITY
vs. CODE
MAX1011-06
DIFFERENTIAL NONLINEARITY
vs. CODE
MAX1003-07
0.50
0.50
0.25
DNL (LSB)
INL (LSB)
0.25
0
0
-0.25
-0.25
-0.50
0
10
20
30
CODE
40
50
60 64
-0.50
0
10
20
30
CODE
40
50
60 64
4
_______________________________________________________________________________________
Low-Power, 90Msps, 6-Bit ADC
Pin Description
PIN
1
2
3
4
5
6
7
8
9, 10,
12, 13
11
14
15
16
17
18
19–24
NAME
GAIN
OCC+
OCC-
IN+
IN-
V
CC
TNK+
TNK-
GND
V
CC
V
CC
N.C.
OGND
V
CCO
DCLK
D0–D5
FUNCTION
Gain-Select Input. Sets input full-scale range: 125/250/500mVp-p (Table 1).
Positive Offset-Correction Compensation. Connect a 0.22µF capacitor for AC-coupled inputs. Ground
pin 2 for DC-coupled inputs.
Negative Offset-Correction Compensation. Connect a 0.22µF capacitor for AC-coupled inputs. Ground
pin 3 for DC-coupled inputs.
Noninverting Analog Input
Inverting Analog Input
+5V ±5% Supply. Bypass with a 0.01µF capacitor to GND (pin 9).
Positive Oscillator/Clock Input
Negative Oscillator/Clock Input
Analog Ground
+5V ±5% Supply. Bypass with a 0.01µF capacitor to GND (pin 10).
+5V ±5% Supply. Bypass with a 0.01µF capacitor to GND (pin 13).
No Connection
Digital Output Ground
Digital Output Supply, +3.3V ±300mV. Bypass with a 47pF capacitor to OGND (pin 16).
Digital Clock Output. Frames the output data.
Digital Outputs 0–5. D5 is the most significant bit (MSB).
MAX1011
_______________Detailed Description
Converter Operation
The MAX1011 integrates a 6-bit analog-to-digital con-
verter (ADC), a buffered voltage reference, and oscilla-
tor circuitry. The ADC uses a flash conversion technique
to convert an analog input signal into a 6-bit parallel
digital output code. The MAX1011’s unique design
includes 63 fully differential comparators and a propri-
etary encoding scheme that ensures no more than
1LSB dynamic encoding error. The control logic inter-
faces easily to most digital signal processors (DSPs)
and microprocessors (µPs) with +3.3V CMOS-compati-
ble logic interfaces. Figure 1 shows the MAX1011 in a
typical application.
Programmable Input Amplifier
The MAX1011 has a programmable-gain input amplifier
with a -0.5dB bandwidth of 55MHz and a true differen-
tial input. To maximize performance in high-speed
systems, the amplifier has less than 3pF of input
capacitance. The input amplifier gain is programmed
via the GAIN pin to provide three possible input full-
scale ranges (FSRs) as shown in Table 1.
Single-ended and differential AC-coupled input circuit
examples are shown in Figures 2 and 3. Each of the
Table 1. Input Amplifier Programming
GAIN
GND
Open
V
CC
INPUT FULL-SCALE RANGE
(mVp-p)
500
250
125
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