EVALUATION KIT AVAILABLE
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
General Description
The MAX44206 is a low-noise, low-distortion fully differential operational amplifier suitable for driving high-speed,
high-resolution, 20-/18-/16-bit SAR ADCs, including the
MAX11905 ADC family. Featuring a combination of wide
2.7V to 13.2V supply voltage range and wide 400MHz
bandwidth, the MAX44206 is suitable for low-power, highperformance data acquisition systems.
The MAX44206 offers a VOCM input to adjust the output
common-mode voltage, eliminating the need for a coupling transformer or AC-coupling capacitors. This adjustable output common-mode voltage allows the MAX44206
to match the input common-mode voltage range of the
ADC following it. Shutdown mode consumes only 6.8µA
and extends battery life in battery-powered applications
or reduces average power in systems cycling between
shutdown and periodic data readings.
The MAX44206 is available in an 8-pin μMAX® package
and is specified for operation over the -40°C to +125°C
temperature range.
Applications
●●
●●
●●
●●
●●
Single-Ended to Differential Conversion
High-Speed Process Control
Medical Imaging
Fully-Differential Signal Conditioning
Active Filters
Features and Benefits
●● Low Input Noise Drives Precision SAR ADCs
• 3.1nV/√Hz at 1kHz
• 200nVP-P from 0.1Hz to 10Hz
●● High Speed for DC and AC Applications
• Gain-Bandwidth Product 400MHz
• -3dB Gain-Bandwidth Product 180MHz
• Slew Rate 180V/µs
●● Ultra-Low Distortion Drives AC Inputs to 20-Bit SAR
ADCs
• HD2 = -141dB, HD3 = -152dB at fIN = 10kHz,
VOUT,DIFF = 2VP-P
• HD2 = -106dB, HD3 = -115dB at fIN = 1MHz,
VOUT,DIFF = 2VP-P
●● Wide Supply Range (2.7V to 13.2V) Drives Unipolar
or Bipolar (±6.6V) Signals
●● 3.7mA Quiescent Supply Current with Only 6.8µA
Shutdown Current
●● 8-Pin μMAX Package Saves Board Space
Ordering Information appears at end of data sheet.
Typical Application Circuit
1kΩ
+5V
HD2 AND HD3 vs. FREQUENCY
0
VS+ = +5V,VS- = -5V
-20
MAGNITUDE (dB)
-40
-
-60
+
-
-80
HD2,NO
LOAD
-100
HD3,NO
LOAD
-120
-140
-160
VS+
VOUTDIFF = 2VP-P
+
INM
1kΩ
IN-
VINM
VCM
VINP
INP
1kΩ
VOCM
OUT+
VOCM
MAX44206
OUT-
IN+
VS10
100
1000
10000
INPUT FREQUENCY (kHz)
µMAX is a registered trademark of Maxim Integrated Products, Inc.
19-7446; Rev 0; 11/14
-5V
OUT+
1kΩ
OUT-
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Absolute Maximum Ratings
VS+ to VS-..............................................................-0.3V to +15V
All Other Pins.................................. (VS-) - 0.3V to (VS+) + 0.3V
IN+ to IN-...............................................................-0.3V to +0.3V
Continuous Input Current into Any Pin (Note 1)................±20mA
Output Short-Circuit Duration (Note 1)................................... 10s
Continuous Power Dissipation (TA = +70°C)
µMAX (derate 10.3mW/°C above +70°C).................824.7mW
Operating Temperature Range.......................... -40°C to +125°C
Junction Temperature.......................................................+150°C
Storage Temperature Range............................. -65°C to +150°C
Lead Temperature (soldering, 10s).................................. +300°C
Soldering Temperature (reflow)........................................+260°C
Package Thermal Characteristics (Note 1)
μMAX
Junction-to-Ambient Thermal Resistance (θJA)........77.6°C/W
Junction-to-Case Thermal Resistance (θJC)..................5°C/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
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 (±5V Supply)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V (Note 2), RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C
to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
13.2
V
POWER SUPPLY
Supply Voltage Range
VS
Quiescent Current
IS
Power-Supply Rejection Ratio
PSRR
VS+ to VS-, guaranteed by PSRR
(EP = VS-)
2.7
No load, RL = ∞
3.7
6.8
mA
SHDN = 0V
6.8
20
µA
VS+ to VS- = 2.7V to 13.2V
(EP = VS-)
90
123
dB
DIFFERENTIAL PERFORMANCE—DC SPECIFICATIONS
Input Common-Mode Range
Input Common-Mode
Rejection Ratio
Input Offset Voltage
Input Offset Voltage Drift
Input Bias Current
Input Offset Current
Open-Loop Gain
Output Short-Circuit Current
Output Voltage Swing
www.maximintegrated.com
VICM
CMRR
Guaranteed by CMRR
VICM = (VS-) + 1.1V to (VS+) - 1.1V
(VS-) + 1.1
94
(VS+) - 1.1
130
V
dB
VOS
±0.2
TCVOS
0.2
IB
30
750
nA
IOS
±15
±350
nA
AVOL
VOUT,DIFF = 6.6VP-P , TA = +25°C
ISC
96
±1.5
µV/°C
130
dB
60
mA
VS+ - VOUT Applies to VOUT+, VOUT
0.98
1.15
VOUT - VS-
0.92
1.10
Applies to VOUT+, VOUT-
mV
V
Maxim Integrated │ 2
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Electrical Characteristics (continued)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V (Note 2), RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C
to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DIFFERENTIAL PERFORMANCE—AC SPECIFICATIONS
Input Voltage-Noise Density
eN
f = 1kHz
3.1
nV/√Hz
0.1Hz < f < 10Hz
200
nVP-P
f = 1kHz
1.5
pA/√Hz
1/f Noise Due to Input Current
0.1Hz < f < 10Hz
220
pAP-P
-3dB Small-Signal Bandwidth
VOUT,DIFF = 0.1VP-P
180
MHz
0.1dB Gain Flatness Bandwidth
VOUT,DIFF = 0.1VP-P
25
MHz
-3dB Large-Signal Bandwidth
VOUT,DIFF = 2VP-P
38
MHz
0.1dB Gain Flatness Bandwidth
VOUT,DIFF = 2VP-P
19
MHz
180
V/µs
5
pF
Input Voltage Noise
Input Current-Noise Density
iN
Slew Rate (Differential)
SR
VOUT,DIFF = 2VP-P
Capacitive Loading
CL
No sustained oscillations
HD2/HD3 Specifications
Settling Time
Output Impedance
tS
ROUT,DIFF
Output Balance Error
SHDN INPUT
Input Voltage
Input Current
VOUT,DIFF = 2VP-P, f = 10kHz
-129/-146
VOUT,DIFF = 2VP-P, f = 1MHz
-90/-98
VOUT,DIFF = 6.6VP-P, f = 10kHz
-124/-142
VOUT,DIFF = 6.6VP-P, f = 1MHz
-86/-90
dBc
Settling to 0.1%, VOUT,DIFF = 4VP-P
58
Settling to 0.1%, VOUT,DIFF = 6.6VP-P
107
fC = 1MHz
0.1
Ω
VOUT,DIFF = 1VP-P, f = 1MHz
-54
dB
VIH
ns
1.25
VIL
0.65
IIH
VSHDN = 2V
IIL
VSHDN = 0V
0.2
-1.5
1.5
-0.2
V
µA
Turn-On Time
tON
Output condition
1.2
µs
Turn-Off Time
tOFF
Output condition
0.8
µs
VOCM INPUT to VOUT,CM PERFORMANCE
Input Voltage Range
Output Common-Mode Gain
Guaranteed by gain parameter
GOCM
∆(VOUT,CM)/∆(VOCM), VOCM = (VS-) + 1.2
to (VS+) - 1.2
(VS-) + 1.2
Output Common-Mode
Rejection Ratio (Note 4)
OCMRR
2 x ∆(VOS,)/∆(VOCM), VOCM = (VS-) + 1.2
to (VS+) - 1.2
V
0.99
1
1.01
V/V
±13
±38
mV
-2
-0.30
µA
100
130
dB
Input Offset Voltage
Input Bias Current
(VS+) - 1.2
-3dB Small-Signal Bandwidth
VOUT,CM = 100mVP-P
16
MHz
Slew Rate
VOUT,CM = 1VP-P
6
V/µs
www.maximintegrated.com
Maxim Integrated │ 3
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Electrical Characteristics (+5V Supply)
(VS+ = +5V, VS- = 0V, VOCM = 2.5V, SHDN = VS+, EP = 0V (Note 2), RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-),
TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
13.2
V
POWER SUPPLY
Supply Voltage Range
VS
Quiescent Current
IS
VS+ to VS-, guaranteed by PSRR
(EP = VS-)
2.7
No load, RL = ∞
3.7
6.8
mA
VSHDN = 0V
5.9
20
µA
DIFFERENTIAL PERFORMANCE—DC SPECIFICATIONS
Input Common-Mode Range
Input Common-Mode
Rejection Ratio
Input Offset Voltage
Input Offset Voltage Drift
Input Bias Current
Input Offset Current
Open-Loop Gain
Output Short-Circuit Current
Output Voltage Swing
VICM
CMRR
Guaranteed by CMRR
VICM = (VS-) + 1.1V to (VS+) - 1.1V
(VS-) + 1.1
94
(VS+) - 1.1
130
V
dB
VOS
±0.2
TC VOS
0.2
IB
30
750
nA
IOS
±15
±350
nA
AVOL
VOUT,DIFF = 2.8VP-P, TA = +25°C
ISC
95
±1.5
µV/°C
120
dB
60
mA
VS+ - VOUT Applies to VOUT+, VOUT
0.95
1.1
VOUT - VS-
0.85
1.1
Applies to VOUT+, VOUT
mV
V
DIFFERENTIAL PERFORMANCE—AC SPECIFICATIONS
Input Voltage-Noise Density
eN
Input Voltage Noise
Input Current-Noise Density
iN
f = 1kHz
3.1
nV/√Hz
0.1Hz < f < 10Hz
200
nVP-P
f = 1kHz
1.5
pA/√Hz
1/f Noise Due to Input Current
0.1Hz < f < 10Hz
220
pAP-P
-3dB Small-Signal Bandwidth
VOUT,DIFF = 0.1VP-P
180
MHz
0.1dB Gain Flatness Bandwidth
VOUT,DIFF = 0.1VP-P
25
MHz
-3dB Large-Signal Bandwidth
VOUT,DIFF = 2VP-P
38
MHz
0.1dB Gain Flatness Bandwidth
VOUT,DIFF = 2VP-P
19
MHz
Slew Rate (Differential)
SR
VOUT,DIFF = 2VP-P
120
V/µs
Capacitive Loading
CL
No sustained oscillations
5
pF
HD2/HD3 Specifications
Settling Time
Output Impedance
Output Balance Error
www.maximintegrated.com
tS
ROUT,DIFF
VOUT = 4VP-P, f = 10kHz
-123/-143
VOUT = 4VP-P, f = 1MHz
-88.5/-95.5
dBc
Settling to 0.1%, VOUT,DIFF = 4VP-P
58
Settling to 0.1%, VOUT,DIFF = 6.6VP-P
100
fC = 1MHz (VOUT,DIFF)
0.1
Ω
VOUT,DIFF = 1VP-P, f = 1MHz
-52
dB
ns
Maxim Integrated │ 4
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Electrical Characteristics (continued)
(VS+ = +5V, VS- = 0V, VOCM = 2.5V, SHDN = VS+, EP = 0V (Note 2), RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-),
TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SHDN INPUT
Input Voltage
Input Current
SYMBOL
CONDITIONS
VIH
MIN
TYP
MAX
1.25
VIL
0.65
IIH
VSHDN = 2V
IIL
VSHDN = 0V
0.2
-1.5
1.5
-0.2
UNITS
V
µA
Turn-On Time
tON
Output condition
1.2
µs
Turn-Off Time
tOFF
Output condition
0.8
µs
VOCM INPUT to VOUT,CM PERFORMANCE
Input Voltage Range
Output Common-Mode Gain
Guaranteed by gain parameter
GOCM
∆(VOUT,CM)/∆(VOCM), VOCM = (VS-) + 1.2
to (VS+) - 1.2
(VS-) +1.2
0.99
Input Offset Voltage
Input Bias Current
Output Common-Mode
Rejection Ratio (Note 4)
OCMRR
2 x ∆(VOS,)/∆(VOCM),
VOCM = (VS-) + 1.2 to (VS+) - 1.2
(VS+)-1.2
V
1
1.01
V/V
±13
±38
mV
-2
-0.3
µA
90
130
dB
-3dB Small-Signal Bandwidth
VOUT,CM = 100mVP-P
16
MHz
Slew Rate
VOUT,CM = 1VP-P
6
V/µs
Note 2: EP is the logic ground reference to the SHDN pin.
Note 3: All devices are 100% production tested at TA = +25°C. Temperature limits are guaranteed by design.
Note 4: OCMRR is mainly determined by external gain resistors matching. The formula used for OCMRR calculation assumes that
gain resistors are perfectly matched. Therefore, OCMRR = (1 + RF/RG) x ∆VOS/∆V(VOCM).
www.maximintegrated.com
Maxim Integrated │ 5
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Typical Operating Characteristics
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V, RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C to +125°C,
unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE
5
4.6
TA = +125°C
4.5
3
SUPPLY CURRENT (mA)
3.5
TA = -40°C
2.5
2
1.5
1
2.5
5
7.5
10
12.5
3.4
3
15
-50
-25
0
25
50
75
100
125
6.8
6.4
VS+ = +2.5V
VS- = -2.5V
6.2
6
5.8
150
VS+ = +5V
VS- = -5V
6.6
-50
-25
75
100
125
INPUT OFFSET VOLTAGE (IN+, IN-)
HISTOGRAM
IN+, IN- INPUT OFFSET VOLTAGE
vs. SUPPLY VOLTAGE
toc4
12
toc05
TA = +25°C
TA = +25°C
8
6
4
0
25
50
75 100
TEMPERATURE (°C)
125
260
TA = +125°C
240
220
Vs = +2.5V
Vs- = -2.5V
Vs+ = +5V
Vs- = -5V
-25
0
25
50
75
TEMPERATURE (°C)
www.maximintegrated.com
100
125
150
200
0.8
TA = -40°C
INPUT OFFSET VOLTAGE CHANGE OVER
TEMPERATURE vs. VICM
toc09a
2
0.2
Vs+ = +2.5V
Vs- = -2.5V
1.5
0.1
TA = +25°C
0
TA = -40°C
-0.1
-0.2
-0.3
-0.4
TA = +125°C
-0.5
-0.6
-0.7
2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10.5 11.5 12.5 13.5
SUPPLY VOLTAGE (V)
toc08
0.3
INPUT OFFSET VOLTAGE VARIATION (mV)
240
-0.8 -0.6 -0.4 -0.2 0
0.2 0.4 0.6
INPUT OFFSET VOLTAGE (μV)
INPUT OFFSET VOLTAGE VARIATION
vs. VOCM
toc07
260
220
0
150
INPUT OFFSET VOLTAGE DRIFT
OVER TEMPERATURE (µV)
-25
-6
-4
150
toc06
280
HISTOGRAM
10
Vs+ = +1.5V
Vs- = -1.5V
-50
50
INPUT OFFSET VOLTAGE (IN+, IN-)
vs. TEMPERATURE (100 UNITS)
2
280
25
TEMPERATURE (°C)
VS+ = +5V
VS- = -5V
-50
0
TEMPERATURE (°C)
300
INPUT OFFSET VOTLAGE (µV)
3.6
7
SUPPLY VOLTAGE (V)
INPUT OFFSET VOLTAGE (IN+, IN-)
vs. TEMPERATURE
200
VS+ = +1.5V
VS- = -1.5V
3.8
toc03
7.2
INPUT OFFSET VOTLAGE (µV)
0
OCCURRENCE (N)
VOS (µV)
1500
1300
1100
900
700
500
300
100
-100
-300
-500
-700
-900
-1100
-1300
-1500
VS+ = +2.5V
VS- = -2.5V
4
3.2
0.5
0
4.2
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
toc02
VS+ = +5V
VS- = -5V
4.4
TA = +25°C
4
SUPPLY CURRENT(mA)
toc01
SHUTDOWN SUPPLY CURRENT (µA)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
-2
0
VOCM (V)
2
4
6
TA = +125°C
1
TA = +25°C
0.5
0
-0.5
-1
-1.5
TA = -40°C
-1.6
-1.2
-0.8
-0.4
0
0.4
0.8
1.2
1.6
VICM (V)
Maxim Integrated │ 6
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Typical Operating Characteristics (continued)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V, RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C to +125°C,
unless otherwise noted.)
INPUT OFFSET VOLTAGE CHANGE OVER
TEMPERATURE vs. VICM
toc09b
1.5
INPUT OFFSET VOLTAGE DRIFT
OVER TEMPERATURE (µV)
2
INPUT OFFSET VOLTAGE DRIFT
OVER TEMPERATURE (µV)
2
VS+ = +1.35V
VS- = -1.35V
TA = -40°C
TA = +25°C
1
0.5
0
-0.5
-1
-0.3
-0.2
-0.1
1.5
OUTPUT VOCM ERROR OVER TEMPERATURE (mV)
TA = +125˚C
1
0.5
0
-0.5
TA = -40˚C
0
0.1
0.2
0.3
-2
0.4
60
50
-4.2
-3
-1.8
-0.6
0.6
VOCM ERROR OVER TEMPERATURE
vs. VOCM INPUT
toc11a
SUPPLY
VOCM
VOCMRANGE
RANGE
VOLTAGE
= =-0.5V
: 3Vto +0.5V
+4V
-4V
Vs+ = +5V
Vs- = -5V
TA = -40˚C
30
INCREASED
SCALE
20
TA = +25˚C
TA = +125˚C
0
-10
1.8
3
-4.2
-3
-1.8
-0.6
0.6
1.8
3
4.2
SUPPLY
VOCM RANGE
VOLTAGE
= -1.5V
-0.5V
: 3Vto +1.5V
+0.5V
Vcc+ = +2.5V
Vcc- = -2.5V
TA = -40˚C
30
20
INCREASED
SCALE
TA = +25˚C
10
TA = +125˚C
0
-10
-1.6
-1.2
-0.8
-0.4
0
0.4
0.8
INPUT VOCM VOLTAGE (V)
-25 -23 -21 -19 -17 -15 -13 -11 -9
-7
-5
VOCM ERROR OVER TEMPERATURE
vs. VOCM INPUT
toc11a
60
SUPPLY
VOCM
VOCMRANGE
RANGE
VOLTAGE
= =-0.5V
-4V
: 3Vto +0.5V
+4V
VS+ = +5V
VS- = -5V
TA = -40˚C
50
40
30
20
TA = +125˚C
10
TA = +25˚C
0
-10
-20
3
3.2
3.4
3.6
3.8
4
4.2
VOCM ERROR OVER TEMPERATURE
vs. VOCM INPUT
toc11b
40
-20
0
4.2
INPUT VOCM VOLTAGE (V)
1.2
1.6
OUTPUT VOCM ERROR OVER TEMPERATURE (mV)
50
6
OUTPUT COMMON-MODE VOLTAGE ERROR (mV)
VOCM ERROR OVER TEMPERATURE
vs. VOCM INPUT
60
8
2
40
-20
10
VICM (V)
10
toc10
TA = +25˚C
VOCM = 0V
4
-1
INPUT VOCM VOLTAGE (V)
OUTPUT VOCM ERROR OVER TEMPERATURE (mV)
12
TA = +25˚C
VICM (V)
www.maximintegrated.com
14
-1.5
TA = +125°C
-0.4
Vs+ = +5V
Vs- = -5V
OUTPUT VOCM ERROR OVER TEMPERATURE (mV)
2.5
OUTPUT COMMON-MODE
VOLTAGE ERROR HISTOGRAM
toc09c
OCCURRENCE (N)
INPUT OFFSET VOLTAGE CHANGE OVER
TEMPERATURE vs. VICM
60
50
toc11b
SUPPLY
VOCM RANGE
VOLTAGE
= -1.5V
-0.5V
: 3Vto +1.5V
+0.5V
Vcc+ = +2.5V
Vcc- = -2.5V
40
TA = -40˚C
30
20
TA = +25˚C
10
TA = +125˚C
0
-10
-20
1.2
1.3
1.4
1.5
1.6
INPUT VOCM VOLTAGE (V)
Maxim Integrated │ 7
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Typical Operating Characteristics (continued)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V, RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C to +125°C,
unless otherwise noted.)
INPUT BIAS CURRENT (IN+/IN-)
vs. INPUT COMMON-MODE VOLTAGE
OUTPUT VOCM ERROR vs. TEMPERATURE
toc12
-12
60
INPUT BIAS CURRENT (nA)
OUTPUT VOCM ERROR (mV)
-12.2
-12.4
-12.6
Vs+ = +2.5V
Vs- = -2.5V
-12.8
-13
-13.2
-13.4
-13.6
-14
-50
-25
0
50
40
TA = +125˚C
30
20
TA = +25˚C
10
0
Vs+ = +5V
Vs- = -5V
-13.8
toc13
70
VOCM INPUT= 0V
-10
25
50
75
100
125
-20
150
TA = -40˚C
-4
-3
IOS (nA)
INPUT BIAS CURRENT (nA)
50
-20
-50
-80
25
0
-25
-50
-110
-75
-100
-125
-50
-25
0
25
50
75
100
125
-150
150
-50
-25
VOCM INPUT BIAS CURRENT
vs. VOCM INPUT VOLTAGE
toc15
0
-0.05
20
15
10
5
10 20 30 40 50
INPUT OFFSET CURRENT (nA)
TA = -40˚C
-0.15
-0.2
-0.25
-0.3
-0.35
TA = +25˚C
-0.4
-0.45
-0.5
-4.2
-3
-1.8
-0.6
0.6
1.8
INPUT VOCM VOLTAGE (V)
3
4.2
toc17
VOCM = 4V
-0.1
-0.15
-0.2
-0.25
VOCM = 3.5V
-0.3
-0.35
-0.4
TA = +125˚C
150
0
VOCM INPUT BIAS CURRENT (µA)
VOCM INPUT BIAS CURRENT (µA)
25
125
VOCM INPUT BIAS CURRENT
vs. TEMPERATURE
-0.1
30
OCCURRENCE (N)
25
50
75 100
TEMPERATURE (°C)
toc16
-0.05
TA = +25˚C
www.maximintegrated.com
4
75
10
INPUT OFFSET CURRENT HISTOGRAM
0
3
toc14b
TEMPERATURE (°C)
-50 -40 -30 -20 -10
2
100
40
-170
0
1
125
-140
35
0
150
VICM = 0V
70
-200
-1
INPUT OFFSET CURRENT (IN+/IN-) vs.
TEMPERATURE (100 UNITS)
INPUT BIAS CURRENT (IN+/IN-)
vs. TEMPERATURE
toc14a
100
-2
INPUT COMMON-MODE RANGE VICM (V)
TEMPERATURE (°C)
-0.45
VOCM = 0V
-50
-25
0
25
50
75
100
125
150
TEMPERATURE (°C)
Maxim Integrated │ 8
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Typical Operating Characteristics (continued)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V, RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C to +125°C,
unless otherwise noted.)
1.2
RLOAD
RLOAD ==200Ω
200Ω
0.8
RLOAD
RLOAD ==10kΩ
10kΩ
0.6
RLOAD
RLOAD ==1kΩ
1kΩ
0.4
Vs+ = +1.5V
Vs- = -1.5V
0.2
0
-50
-25
0
25
50
75
100
125
0.8
RLOAD
RLOAD ==10kΩ
10kΩ
0.6
0.2
Vs+ = +2.5V
Vs- = -2.5V
-50
-25
0
TEMPERATURE (°C)
OUTPUT VOLTAGE HIGH VOH (V)
OUTPUT VOLTAGE HIGH VOL (V)
0.8
RLOAD = 1kΩ
0.4
0.2
0
-25
0
25
50
75
100
125
100
Vs+ = +5V
Vs- = -5V
-50
-25
0
125
0.6
0.4
0
150
RLOAD = 1kΩ
Vs+ = +2.5V
Vs- = -2.5V
-50
-25
0
25
50
75
100
125
SHDN INPUT CURRENT (nA)
-100
-150
-200
-250
100
125
150
toc19c
1.2
RLOAD = 200Ω
1
0.8
0.6
RLOAD = 10kΩ
0.4
0.2
0
150
RLOAD = 1kΩ
SHORT-CIRCUIT PROTECTION OCCURS AT
RLOAD = 200Ω at 125°C
-50
-25
0
25
50
75
100
125
150
toc20b
VSHDN = 2V
300
-50
75
TEMPERATURE (ᵒC)
350
VSHDN = 0V
50
1.4
SHDN INPUT CURRENT
vs. SHDN INPUT VOLTAGE
toc20a
25
1.6
TEMPERATURE (ᵒC)
0
SHDN INPUT CURRENT (nA)
0.4
VOL vs. TEMPERATURE
vs. LOAD RESISTOR
0.8
RLOAD = 10kΩ
RLOAD = 1kΩ
TEMPERATURE (ᵒC)
SHDN INPUT CURRENT
vs. SHDN VOLTAGE vs. TEMPERATURE
250
200
150
100
50
-50
-25
0
25
50
75
TEMPERATURE (°C)
www.maximintegrated.com
RLOAD = 10kΩ
0.6
0
1
TEMPERATURE (ᵒC)
-300
0.8
150
RLOAD = 200Ω
0.2
Vs+ = +1.5V
Vs- = -1.5V
-50
75
1
0.2
toc19b
1.2
RLOAD = 200Ω
RLOAD = 10kΩ
50
1.2
VOL vs. TEMPERATURE
vs. LOAD RESISTOR
toc19a
1.2
0.6
25
toc18c
RLOAD = 200Ω
1.4
TEMPERATURE (ᵒC)
VOL vs. TEMPERATURE
vs. LOAD RESISTOR
1
RLOAD
RLOAD ==1kΩ
1kΩ
0.4
0
150
RLOAD = 200Ω
1
VOH vs. TEMPERATURE
vs. LOAD RESISTOR
1.6
OUTPUT VOLTAGE HIGH VOH (V)
1
toc18b
1.2
OUTPUT VOLTAGE HIGH VOH (V)
OUTPUT VOLTAGE HIGH VOH (V)
VOH vs. TEMPERATURE
vs. LOAD RESISTOR
toc18a
OUTPUT VOLTAGE HIGH VOH (V)
VOH vs. TEMPERATURE
vs. LOAD RESISTOR
100
125
150
0
-50
-25
0
25
50
75
100
125
150
TEMPERATURE (°C)
Maxim Integrated │ 9
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Typical Operating Characteristics (continued)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V, RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C to +125°C,
unless otherwise noted.)
toc21a
1
0.99
0.98
0.97
0.96
VSHDNTH+
0.95
0.94
0.93
0.92
VSHDNTH-
0.91
0.9
-50
-25
0
25
50
75
100
125
toc21b
1
Vs+ = +5V
Vs- = -5V
SHDN INPUT THRESHOLD VOLTAGE (V)
SHDN INPUT THRESHOLD VOLTAGE (V)
SHDN INPUT THRESHOLD VOLTAGE
vs. TEMPERATURE
SHDN INPUT THRESHOLD VOLTAGE
vs. TEMPERATURE
0.99
0.98
0.97
0.96
VSHDNTH+
0.95
0.94
0.93
0.92
VSHDNTH-
0.91
0.9
150
Vs+ = +2.5V
Vs- = -2.5V
-50
-25
0
TEMPERATURE (°C)
INPUT OFFSET VOLTAGE
vs. SUPPLY VOLTAGE
50
75
100
125
150
toc22
25
INPUT OFFSET VOLTAGE (uV)
25
TEMPERATURE (°C)
20
15
10
5
0
2.5
4.5
6.5
8.5
10.5
12.5
SUPPLY VOLTAGE (V)
OUTPUT SHORT-CIRCUIT CURRENT
vs. TEMPERATURE
VOCM = 0V,
VIN+ = VIN- = 0V,
OUT+ SHORTED TO VS-
Vs+ = +5V
Vs- = -5V
90
80
70
60
50
Vs+ = +2.5V
Vs- = -2.5V
-50
-25
0
25
50
75
TEMPERATURE (°C)
www.maximintegrated.com
100
125
150
toc23b
-30
SHORT-CIRCUIT CURRENT (mA)
SHORT-CIRCUIT CURRENT (mA)
100
40
OUTPUT SHORT-CIRCUIT CURRENT
vs. TEMPERATURE
toc23a
VOCM = 0V,
VIN+ = VIN- = 0V,
OUT+ SHORTED TO VS+
Vs+ = +5V
Vs- = -5V
-40
-50
-60
-70
-80
Vs+ = +2.5V
Vs- = -2.5V
-50
-25
0
25
50
75
100
125
150
TEMPERATURE (°C)
Maxim Integrated │ 10
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Typical Operating Characteristics (continued)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V, RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C to +125°C,
unless otherwise noted.)
SMALL-SIGNAL GAIN vs. FREQUENCY
SMALL-SIGNAL GAIN vs. FREQUENCY
toc25
toc24
30
4
2
0
VOUTDIFF = 0.1VP-P
GAIN = 10V/V
10
-2
MAGNITUDE (dB)
MAGNITUDE (dB)
20
0
-10
VOUTDIFF = 0.1VP-P
GAIN = 1V/V
-20
-6
-8
-10
-12
-14
-16
-30
-40
VOUTDIFF = 0.1VP-P
VS+ = +5V,
VS- = -5V
-4
-18
0.01
1
100
10000
1000000
-20
0.01
1
toc26
5
0
MAGNITUDE (dB)
MAGNITUDE (dB)
VOUTDIFF = 0.1VP-P
VOCM = 1.65V (BLACK TRACE),
VOCM = 0V (RED TRACE)
-5
-10
-15
0.01
1
100
10000
FREQUENCY (kHz)
toc28
-10
-15
1000000
-25
0.01
1
100
-5
VOUTDIFF = 2VP-P
GAIN = 1V/V
VOCM = 0V
-10
-15
0.01
1
100
FREQUENCY (kHz)
www.maximintegrated.com
10000
1000000
-4
-6
-8
-10
CF=10pF
-4
-6
-8
-10
-12
-12
-14
-14
-16
-16
CF = NO LOAD
0
MAGNITUDE (dB)
MAGNITUDE (dB)
0
toc30
2
-2
VOUTDIFF = 2VP-P,
VOCM = 1.65V
GAIN = 1V/V
-2
5
1000000
LARGE-SIGNAL GAIN vs. FREQUENCY
toc29
0
VOUTDIFF = 2VP-P
GAIN = 10V/V
VOCM = 0V
10000
FREQUENCY (kHz)
2
20
MAGNITUDE (dB)
VOUTDIFF = 0.1VP-P
ENTER
TEXTTRACE),
CLOAD = 10pF
(BLACK
HERE (RED TRACE)
CLOAD = NO LOAD
LARGE-SIGNAL GAIN vs. FREQUENCY
LARGE-SIGNAL GAIN vs. FREQUENCY
25
-20
-5
-20
-20
10
1000000
toc27
5
0
15
10000
SMALL-SIGNAL GAIN vs. FREQUENCY
SMALL-SIGNAL GAIN vs. FREQUENCY
-25
100
FREQUENCY (kHz)
FREQUENCY (kHz)
0.01
1
100
10000
FREQUENCY (kHz)
1000000
-18
VOUTDIFF = 2VP-P
CF = NO CAP, 10pF
CF is Feedback Capacitor
0.01
1
100
10000
FREQUENCY (kHz)
1000000
Maxim Integrated │ 11
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Typical Operating Characteristics (continued)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V, RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C to +125°C,
unless otherwise noted.)
LARGE-SIGNAL GAIN FLATNESS
vs. FREQUENCY
LARGE-SIGNAL GAIN vs. FREQUENCY
toc31
5
0.5
-10
-15
-20
0.2
0.1
0
-0.1
VOUTDIFF = 2VP-P
-0.2
-0.3
-25
10000
-0.5
1000000
0.01
1
OUTPUT BALANCE ERROR vs. FREQUENCY
-20
-40
VS+ = +2.5V
VS- = -2.5V
-40
-50
VS+ = +5V
VS- = -5V
0.01
1
100
10000
PSRR+ vs. FREQUENCY
1000000
0.01
1
100
MAGNITUDE (dB)
MAGNITUDE (dB)
PHASE
1
100
FREQUENCY (kHz)
www.maximintegrated.com
-40
RED
TRACE
VS+ = +5V
VS- = -5V
-60
-70
1000000
0.01
1
30
120
100
20
80
CROSSOVER POINT:
GAIN = 0
FREQUENCY = 400MHz
PHASE = 87°(rad)
-10
RF = 1kΩ , RG = 10Ω
0.01
1
100
10000
FREQUENCY (kHz)
10000
1000000
60
40
20
0
1000000
INPUT VOLTAGE-NOISE DENSITY
vs. FREQUENCY
toc39
100
140
0
10000
200
180
GAIN
100
FREQUENCY (kHz)
160
10
PSRR+
toc36
-30
-50
UNITY-GAIN BANDWIDTH AND PHASE
vs. FREQUENCY
toc38
60
40
-90
0.01
10000
50
-70
-130
-20
FREQUENCY (kHz)
-50
1000000
BLACK
TRACE
VS+ = +2.5V
VS- = -2.5V
-10
RED TRACE
VS+ = +5V
VS- = -5V
-120
toc37
10000
VIN = 1VP-P
RF = RG = 1kΩ MATCHED 0.1% RESISTORS
10
-100
-140
100
VOCM OUTPUT AC CMRR
vs. FREQUENCY
20
BLACK
TRACE
VS+ = +2.5V
VS- = -2.5V
-80
PSRR-
-110
1
0
-60
VS+ = +5V
VS- = -5V
-30
0.01
FREQUENCY (kHz)
VIN = 1VP-P
RF = 1kΩ , RG = 10Ω
FREQUENCY (kHz)
-10
-60
1000000
MAGNITUDE (dB)
-20
MAGNITUDE (dB)
MAGNITUDE (dB)
-10
-70
10000
toc35
0
VIN = 1VP-P
-60
100
INPUT AC CMRR vs. FREQUENCY
toc34
-30
RED TRACE:
VOCMIN = 10mVP-P
FREQUENCY (kHz)
FREQUENCY (kHz)
0
-30
INPUT VOLTAGE-NOISE DENSITY (nV/√Hz)
100
BLACK TRACE:
VOCMIN = 100mVP-P
-20
-50
PHASE (radians)
1
-10
-40
VOUTDIFF = 1VP-P
-0.4
0.01
MAGNITUDE (dB)
MAGNITUDE (dB)
MAGNITUDE (dB)
-5
0
VOUTDIFF = 0.5VP-P
0.3
VOUTDIFF = 2VP-P
CLOAD = 0pF, 10pF
toc33
10
0.4
0
-30
VOCM RESPONSE vs. FREQUENCY
toc32
10
1
0.1
1
10
100
1000
10000 100000
FREQUENCY (Hz)
Maxim Integrated │ 12
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Typical Operating Characteristics (continued)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V, RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C to +125°C,
unless otherwise noted.)
10
HD2 AND HD3 vs. FREQUENCY
(VOUTDIFF = 1VP-P)
0
-20
-40
-40
-60
-80
HD2,1K load
-100
HD2,No load
10
100
1000
-160
10000 100000
10
100
FREQUENCY (Hz)
-20
-40
-40
-60
HD2,1K load
HD2,no load
-100
-140
-160
10
100
1000
-160
150
INPUT VOLTAGE NOISE (nVP-P)
MAGNITUDE(dB)
fIN = 1MHz
fIN = 100kHz
fIN = 10kHz
1
2.4
3.8
10
100
1000
5.2
0
-50
-100
6.6
-150
4s/div
toc45
fIN = 11.5MHz
fIN = 1MHz
-100
fIN = 100kHz
-120
fIN =1 0kHz
1
2.4
3.8
5.2
6.6
OUTPUT VOLTAGE SWING (VP-P)
INPUT CURRENT NOISE 0.1Hz to 10Hz
150
0.1Hz TO 10Hz INPUT VOLTAGE NOISE: 200nVP-P
50
10000
HD2 vs. OUTPUT SWING
-80
-140
10000
toc47
100
1000
-60
0.1Hz to 10Hz INPUT VOLTAGE NOISE
toc46
-140
-160
100
-40
INPUT FREQUENCY (kHz)
-60
-120
10
0
HD3,No load
HD3,1K load
-140
-40
-100
HD2,1K load
HD2,no load
-120
fIN = 11.5MHz
-80
toc44
-100
10000
HD3 vs. OUTPUT SWING
-20
HD3,No load
HD3,1K load
-20
-80
INPUT FREQUENCY (kHz)
0
HD2,no load
INPUT FREQUENCY (kHz)
-60
HD3,No load
HD3,1K load
-120
-160
10000
HD2 AND HD3 vs. FREQUENCY
(VOUTDIFF = 6.6VP-P)
0
MAGNITUDE(dB)
MAGNITUDE(dB)
toc43
-20
-80
HD2,1K load
-100
INPUT FREQUENCY (kHz)
HD2 AND HD3 vs. FREQUENCY
(VOUTDIFF = 4VP-P)
0
1000
MAGNITUDE (dB)
1
-80
-140
INPUT CURRENT NOISE (pAP-P)
0.1
toc42
-60
-120
HD3,No load
HD3,1K load
-140
HD2 AND HD3 vs. FREQUENCY
(VOUTDIFF = 2VP-P)
0
-20
-120
1
toc41
MAGNITUDE(dB)
toc40
MAGNITUDE(dB)
INPUT CURRENT-NOISE DENSITY (pA/√Hz)
100
INPUT CURRENT-NOISE SPECTRAL DENSITY
vs. FREQUENCY
toc48
INPUT CURRENT NOISE = 220pAP-P
100
50
0
-50
-100
-150
4s/div
OUTPUT VOLTAGE SWING(Vp-p)
www.maximintegrated.com
Maxim Integrated │ 13
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Typical Operating Characteristics (continued)
(VS+ = +5V, VS- = -5V, VOCM = 0V, SHDN = VS+, EP = 0V, RF = RG = 1kΩ, RL = 1kΩ (between OUT+ and OUT-), TA = -40°C to +125°C,
unless otherwise noted.)
LARGE-SIGNAL TRANSIENT RESPONSE
LARGE-SIGNAL TRANSIENT RESPONSE
SMALL-SIGNAL RESPONSE
toc50b
toc50a
toc49
CLOAD = 10pF
CLOAD = 10pF
VINDIFF
VINDIFF
500mV/div
100mV/div
VOUTDIFF
100mV/div
500mV/div
VOUTDIFF
50ns/div
VINDIFF
500mV/div
500mV/div
VOUTDIFF
50ns/div
50ns/div
VOCM SMALL-SIGNAL
TRANSIENT RESPONSE
VOCM LARGE-SIGNAL
TRANSIENT RESPONSE
toc51
VOCM
100mV/div
100mV/div
VOUT+
toc52
VOCM
2V/div
2V/div
VOUT+
100ns/div
500ns/div
OUTPUT-TRANSIENT RESPONSE
vs. SHUTDOWN PULSE
OUTPUT+ TRANSIENT RESPONSE
vs. SHUTDOWN PULSE
toc53a
toc53b
VSHDN
2V/div
VSHDN
2V/div
VOUT-
1V/div
VOUT+
1V/div
5µs/div
5µs/div
www.maximintegrated.com
5µs/div
Maxim Integrated │ 14
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Pin Configuration
TOP VIEW
IN-
1 +
VOCM
2
VS+
3
OUT+
4
MAX44206
*
8
IN+
7
SHDN
6
VS-
5
OUT-
µMAX
*EP = EXPOSED PAD
Pin Description
PIN
NAME
1
IN-
2
VOCM
FUNCTION
Inverting Input
Output Common-Mode Voltage Input
3
VS+
4
OUT+
Positive Supply Voltage Input
Noninverting Differential Output
5
OUT-
Inverting Differential Output
6
VS-
7
SHDN
8
IN+
Noninverting Input
—
EP
Exposed Pad. EP is the logic ground reference to the SHDN pin.
www.maximintegrated.com
Negative Supply Voltage Input
Shutdown Mode Input (Active-Low). SHDN is referred to the exposed pad.
Maxim Integrated │ 15
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Functional Diagram
INN
RF
RG
VS+
SHDN
CC
MAX44205
GAIN
STAGE
OUTPUT
STAGE
OUT+
ININPUT
STAGE
IN+
COMMON-MODE
FEEDBACK
VOCM INPUT
GAIN
STAGE
OUTPUT
STAGE
VOCM
OUT-
CC
VSINP
RG
Detailed Description
The MAX44206 is a low-noise, low-power, very low-distortion fully differential (input and output) op amp capable
of driving high-resolution 16-/18-/20-bit SAR ADCs with
input signal frequencies from DC to 1MHz. These highresolution signal chain ICs are used in test and measurement applications, as well as medical instrumentation and
industrial control systems.
This fully differential op amp accepts either single-ended
or fully differential input signals at its inputs and converts the input signal into fully differential outputs that
are exactly equal in amplitude and 180° apart in phase.
Ideally, the noise and distortion performance of the ampli-
www.maximintegrated.com
RF
fier should match or exceed the linearity of the ADC to
preserve the overall system accuracy.
Four precisely matched resistors (two for feedback and
two for gain setting) set the differential closed-loop gain
as shown in the Functional Diagram.
The MAX44206 has an output voltage common-mode
(VOCM) input to set the DC common-mode voltage level
of the differential outputs without affecting the balance
of the AC differential output signal on each output. The
MAX44206 also features a low-power shutdown mode
that consumes only 6.8µA of supply current from the VS+
pin. Note that while the outputs are high impedance during shutdown, the feedback networks may provide paths
for current to flow from the input source(s).
Maxim Integrated │ 16
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Terminology and Definitions
With single-ended input applications, there will be an
input signal component to the input common-mode voltage, as there is no out-of-phase signal not applied on the
other input. Applying VINP (connecting VINM to zero), the
common-mode input voltage is:
RF
+5V
INM
RG
SHDN
INVOCM
INP
VIN,cm = (VIN+ + VIN-)/2 ≅ VOCM x RG/(RF + RG) +
VCM x RF/(RF + RG) + VINP/2 x RF/(RF + RG)
VS+
OUT+
VOCM
RG
OUT+
MAX44206
OUT-
IN+
OUT-
RF
Figure 1. Differential Input, Differential Output Configuration
(Decoupling Capacitors Not Shown for Simplicity)
Differential Voltage
The differential voltage at the input is the voltage applied
across INP to INM and the differential voltage at the output is the voltage across OUT+ to OUT-. Equations for
input and output differential voltages are listed below:
VIN,dm = (VINP - VINM)
VOUT,dm = (VOUT+ - VOUT-)
VOUT+ and VOUT- are voltages at the OUT+ and OUTterminals with respect to output common-mode voltage
set by the VOCM input voltage.
Common-Mode Voltage
The common-mode voltage at the input is the average
of the input pins (IN+ and IN-) and at the output, it is the
average of two outputs. Equations for input and output
common-mode voltages are listed below:
VIN,cm = (VIN+ + VIN-)/2
VOUT,cm = VOCM = (VOUT+ + VOUT-)/2
Though it was mentioned that the input common-mode
voltage is the average of the voltage seen on both input
pins, the range is slightly different depending on if the
input signal is fully differential or single ended.
For fully differential input applications, where VINP =
-VINM, the common-mode input voltage is:
VIN,cm = (VIN+ +VIN-)/2 ≅ VOCM x RG/(RF + RG)
+ VCM x RF/(RF + RG)
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The common-mode offset voltage is defined as the difference between the voltage applied to the VOCM terminal
and the output common-mode voltage.
VOS,cm = (VOUT,cm - VOCM)
Input Offset Voltage, CMRR, and VOCM CMRR
VS-
-5V
Common-Mode Offset Voltage
Input offset voltage is the differential voltage error (VOS,dm)
between the input pins (IN+ and IN-). CMRR performance
is affected by both the input offset voltage error at the input
due to change in input common-mode voltage (VIN_,cm)
and the change in input offset voltage VOS,dm) due to
VOCM change. So, there are two CMRR terms:
CMRRVIN,cm = ∆(VIN_,cm)/∆(VOS,dm)
CMRRVOCM = ∆(VOCM)/∆(VOS,dm)
The output common-mode rejection ratio is strongly
affected by the matching of gain-setting feedback network.
Output Balance Error
An ideal differential output implies the two outputs of the
amplifier should be exactly equal in amplitude but 180°
apart in phase. Output balance is the measure of how well
the outputs are balanced and is defined as the ratio of the
output common-mode voltage to the output differential
signal. It is generally expressed as dB in log scale.
Output Balance Error = 20 x log|(VOUT,cm)/(VOUT,dm)|
Operation and Equations
The Functional Diagram details the internal architecture
of the differential op amp. The negative feedback loop
across the outputs to respective inputs force voltages on
IN+ and IN- pins equal to each other. That implies:
VINP − VOUT −
=
RF
RG
VINN − VOUT +
=
RF
RG
From above equations see the relationship between differential output voltage and inputs.
(VOUT + − VOUT − ) = (VINP − VINN ) ×
RF
RG
Maxim Integrated │ 17
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
The VOCM input voltage with the help of the commonmode feedback circuit drives the output common-mode
voltage level to VOCM. This results in the following output
relations:
(V=
OUT + ) (VOCM) +
(V=
OUT − ) (VOCM) −
and back-to-back diode protection between the inputs for
protection against excessive differential voltages across
the amplifier’s inputs.
SHDN and Exposed Pad
Shutdown Operation
VOUT,DM
The MAX44206 offers a shutdown mode for low-power
operation. Drive SHDN below 0.65V with respect to the
µMAX exposed pad (EP) to shut down the part and only
6.8µA (typ) will be drawn from VS+. To keep the part
active, SHDN needs to be at least 1.25V above EP.
2
VOUT,DM
2
Input and ESD Protection
As shown in Figure 2, ESD diodes are present on all the
pins with respect to the VS+ and VS- pins so that these
ESD diodes turn on and protect the part when voltages on
these pins go out of range from either supplies by more
than one diode drop. There are two series input resistors
Exposed Pad
EP is the logic ground reference to the SHDN pin. EP
should be connected to the PCB ground plane for optimum thermal dissipation.
VS+
D1
MAX44206
SHDN
D1
VSVS+
VS+
D1
D1
IN-
25Ω
D1
IN+
D1
VS-
VS+
D1
D1
D1
25Ω
VS-
ESD
CORE
CLAMP
VOCM
VS+
VS-
D1
VS-
D1
VS+
D1
OUT+
D1
OUT-
D1
VS-
VS-
Figure 2. Showing ESD Protection Scheme in MAX44206
www.maximintegrated.com
Maxim Integrated │ 18
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Shutdown Operation with External
Components and Stimuli
are applied to INP and INN. The voltage applied to the
VOCM pin sets the output common-mode voltage.
In shutdown mode, quiescent supply current is low.
However, there will be currents flowing into the IC pins
depending on the external components and applied signals. Figure 3 shows the block diagram with these current
paths and Figure 2 shows internal protection devices. In
active operation mode (shutdown disabled), input signals
In shutdown mode, the voltages applied to INP, INN, and
VOCM will interact with the IC internal components resulting in current flowing into the IC pins. It must be noted
that the op amp’s outputs, OUT+ and OUT-, exhibit highimpedance state in shutdown mode.
RF
SHDN
VS+
D1
MAX44206
D1
VSVS+
VS+
INN RG
D1
IN-
VS-
VS+
IINP
D1
IN+
INP
25Ω
GAIN
D1
IINN
D1
D1
INPUT
STAGE
OUTPUT
25Ω
OUTPUT
D1
VS-
IVOCM
VS+
D1
D1
VS-
ESD
CORE
CLAMP
VOCM
D1
VS-
OUT+
D1
VS+
VOCM
COMMONINPUT
MODE
FEEDBACK
GAIN
RG
D1
CC
OUT-
D1
CC
VS-
VSRF
Figure 3. Currents Flowing when MAX44206 is in Shutdown
www.maximintegrated.com
Maxim Integrated │ 19
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Applications Information
The fully differential op amp is shown in Figure 4 for reference. Fully differential op amps provide a lot of advantages, including rejecting common-mode noise coupled
to the input, the output, and from the power supply. The
effective output swing is increased by a factor of two
as the outputs are equal in amplitude and 180° apart in
phase.
For example, by applying a fully differential input signal of
1VP-P across INP and INN on Figure 1 there is a 1VP-P
differential output voltage swing. Another advantage of
having fully differential outputs is that even order harmonics will be suppressed at the output.
Input Impedance Mismatch Due
to Source Impedance
For a single-ended input signal, since the inputs are not
balanced, the input impedance actually increases relative
to the fully differential case. The input impedance looking
into either input is:
R=
INP R=
INM
RG
RF
1
[1 − ×
]
2 (R G + R F )
Apart from the single-ended input and differential input
signal cases, an input signal source from a nonzero
source impedance may cause imbalance between feedback resistor networks for single-ended input driving case
as shown in the Figure 6. A terminating resistor RT as
shown in Figure 6 is used to impedance match to the
source such that:
=
R T R INM ×
The impedance looking into the IN+ and IN- nodes of
Figure 5 depends on how the inputs are driven. For a
fully differential input signal, i.e., VINP = VINM + 180°. The
input impedance looking into inputs is shown in Figure 5.
RS
R INM − R S
RF
RINP = RINM = RG
+5V
DIFFERENTIAL STRUCTURE AT INPUT, OUTPUT REJECTS COUPLED
NOISE AT THE INPUT, OUTPUT AND AT THE POWER SUPPLY
VS+
INOUT+
VOCM
MAX44206
OUT-
IN+
OUT+
+
+
OUT-
VS+
RG
INM
-
VS+
VOCM
RINM
INVINM
VINP
VCM
RG
VOCM
OUT+
VOCM
OUT+
MAX44206
OUT-
IN+
OUT-
INP
RINP
VS-
VS-
-5V
RF
VS-
Figure 4. Fully Differential Op Amp
www.maximintegrated.com
Figure 5. Showing Fully Differential Architecture
Maxim Integrated │ 20
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
A terminating resistor is inserted to correct for impedance
mismatch between the source and input. The gain resistor mismatch across feedback networks is created due to
the parallel combination of RT and RS. So, to balance out
the gain resistor mismatch on the other input, insert RB
such that:
R=
B RT ×
RS
RT − RS
The MAX44206 input-referred voltage noise contributes
the equivalent noise of a 600Ω resistor. For low noise,
keep the source and feedback resistance at or below this
value, i.e. RS + RG//RF ≤ 600Ω. At combinations of below
600Ω, amplifier noise is dominant, but in the region 600Ω
to 10kΩ, the noise is dominated by resistor thermal noise.
Any larger resistances beyond that, the noise current multiplied by the total resistance dominated the noise.
RF
Effects of Input Resistor Mismatch
If there is a mismatch between the feedback resistor (RF)
pair and gain resistor (RG) pair, there will be a small delta
in the feedback factor across the input pins. This delta in
the feedback factor is a source of common-mode error.
To apply an AC CMRR test without a differential input
signal, the common-mode rejection is proportional to
the resistor mismatch. Using 0.1% or better resistors will
mitigate most of the problems and will yield good CMRR
performance.
RINM
IN-
VINM
VOCM
RB = RS//RT
enRF is the noise voltage density contributed by the feedback resistor RF
Resistor Noise =
4 × k × T × R × ∆f in nV/√Hz
MAX44206
OUT-
VS-
OUT-
RF
Figure 6. Compensation for Source Impedance
RF
+5V
VS+
INM
RG
IN-
in is the input current-noise density
enRG is the noise voltage density contributed by the gain
resistor RG
OUT+
VS-
R
+2 × (e nRG × F ) 2 + 2 × (e nRF ) 2
RG
en is the input voltage-noise density
VOCM
IN+
RF 2
)] + 2 × (i n × R F ) 2
RG
ent is total output noise of the circuit shown in Figure 7
OUT+
RT
RG
The MAX44206 offers input voltage and current noise
densities of 3.1nV/√Hz and 1.5pA/√Hz, respectively. From
Figure 7, the total output noise is a combination of noise
generated by the amplifier and the feedback and gain
resistors. The total output noise generated by both the
amplifier and the feedback components is given by the
equation:
e nt =
VS+
RG
RS
Noise Calculations
[e n × (1 +
VS+
SIGNAL
GENERATOR
VOCM
INP
VOCM
RG
OUT+
OUT+
MAX44206
OUT-
IN+
OUT-
VS-
T is absolute temperature in Kelvin
k is Boltzmann constant: k = 1.38 x 10-23 in joules/Kelvin
R is resistance in ohms and ∆f is frequency range in Hertz
-5V
RF
Figure 7. Fully Differential Amplifier
www.maximintegrated.com
Maxim Integrated │ 21
MAX44206
Lower resistor values are ideal for low-noise performance
at the cost of increased distortion due to increased loading of the feedback network on the output stage. Higher
resistor values will yield better distortion performance
due to less loading on the output stage but at the cost of
increase in higher output noise.
Improving Stability Using
Feedback Capacitors
When the MAX44206 is configured such that a combination of parasitic capacitances at the inverting input form
a pole whose frequency lies within the closed-loop bandwidth of the amplifier, a feedback capacitor across the
feedback resistor is needed to form a zero at a frequency
close to the frequency of the parasitic pole to recover the
lost phase margin.
Adding larger value feedback capacitors will reduce the
peaking of the amplifier but decreases the closed-loop
-3dB bandwidth.
Layout and Bypass Capacitors
For single-supply applications, it is recommended to place
a 0.1µF NPO or C0G ceramic capacitor within 1/8th of
an inch from the VS+ pin to ground and to also connect
a 10µF ceramic capacitor within 1 inch of the VS+ pin to
GND.
In dual-supply applications, it is recommended to install
0.1µF NPO or C0G ceramic capacitor within 1/8th of an
inch from the VS+ and VS- pins to GND and place 10µF
ceramic capacitors within 1 inch of the VS+ and VS- pins
to GND. Low ESR\ESL NPO capacitors are recommended for 0.1µF or smaller decoupling capacitors. A 0.1µF or
0.22µF capacitor is a good choice close to VOCM input
pin to ground.
Signal routing into and out of the part should be direct
and as short as possible into and out of the op amp
inputs and outputs. The feedback path should be carefully
routed with the shortest path possible without any parasitic capacitance forming between feedback trace and
board power planes. Ground and power planes should be
www.maximintegrated.com
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
removed from directly under the amplifier input and output
pins. Also, care should be taken such that there will be no
parasitic capacitance formed around the summing nodes
at the inputs that could affect the phase margin of the part.
Any load capacitance beyond a few picofarads needs to
be isolated using series output resistors placed as close
as possible to the output pins to avoid excessive peaking
or instability.
Driving a Fully Differential ADC
The MAX44206 was designed to drive fully differential
SAR ADCs such as the MAX11905. The MAX11905 is
part of a family of 20-/18-/16-bit, 1.6Msps/1Msps ADCs
that offer excellent AC and DC performance. Figure 8
details a fully differential input to the MAX44206, which
then drives the fully differential MAX11905 ADC inputs
through the ADC input filter shown in the dashed box.
The MAX6126 provides a 3V reference output voltage,
which is fed to the ADC’s reference. The MAX44206’s
common mode (VOCM) is created by dividing down the
reference voltage by a factor of two. A pair of 1kΩ 0.1%
resistors are used for this purpose. The VOCM input is
bypassed to GND with a combination of 2.2µF (X7R) and
0.1µF (NPO) capacitors.
The MAX44206 is connected in a unity-gain configuration.
The input resistors and feedback resistors are all 1kΩ
0.1% resistors. The feedback resistors are bypassed by
a pair of 4.7nF (C0G, 100V) capacitors. These feedback
components roll the amplifier off to about 60MHz corner
frequency.
The ADC input filter uses a pair of 10Ω 0.1% resistors
and a 2.2nF (C0G) capacitor. This input filter assists the
MAX44206’s settling response with the MAX11905’s fast
acquisition window.
Figure 8 was used to test the AC performance in Figures
9 and 10. Data were taken with the input frequencies
at 10kHz on the MAX11905 Evaluation Kit. Figures 9
to 13 detail the results of the MAX11905 Evaluation Kit
(MAX11905DIFEVKIT#) GUI.
Maxim Integrated │ 22
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
3V
3.2V TO 12.6V
IN
OUT
MAX6126
GND
4.7nF
C0G
10µF
1kΩ
0.1%
1kΩ
0.1%
+5V
-
VS+
VSIG
1kΩ
0.1%
3.3V
SHDN
+
10Ω 0.1%
OUT+
2.2µF
X7R
1.5V
0.1µF
VOCM
MAX44206
OUT-
VCM
1kΩ
0.1%
+
1kΩ
0.1%
-5V
MAX11905
AINGND
ADC INPUT FILTER
VS-
VSIG
REFVDD VREFIN AVDD
AIN+
2.2nF
COG
10Ω 0.1%
3.3V
1kΩ
0.1%
4.7nF
C0G
Figure 8. MAX44206 Driving a 20-Bit MAX11905 SAR ADC
www.maximintegrated.com
Maxim Integrated │ 23
MAX44206
The sample rate for Figure 9 is 1Msps and the sample
rate for Figure 10 is 1.6Msps, the MAX11905’s maximum
sample rate. As measured at the MAX11905 output, the
signal-to-noise ratio is > 97dB for both sample rates, with
total harmonic distortion > 112.9dB.
Figures 11 to 13 detail the DC performance of the
MAX44206 and MAX11905. These three figures detail
the results of shorting the inputs together to GND at the
VSIG sources and measuring the noise histogram at the
output of the ADC. All data was measured at 1Msps, with
65,536 samples taken. Figure 11 shows the results at a
20-bit code level with no averaging. Effective number of
bits (ENOB) is 17.9 bits.
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
One technique to improve a system’s ENOB is to average multiple samples. The tradeoff is a reduced effective
sample rate. The theoretical expected results of averaging are a 0.5 improvement in ENOB for every average
factor of 2. Therefore, averaging by 16x should improve
ENOB by 2 bits. Figure 12 details this example, and the
ENOB is improved nearly 2 bits, from 17.9 bits to 19.8
bits. This shows that the noise from the ADC and the op
amp are not limiting the ENOB.
Figure 13 shows the results of averaging by 64x, which
will limit the effective sample rate to 15.6ksps (1Msps/64).
ENOB is 20.8 bits in this mode, making the MAX11905 a
lower power alternative to high-speed 24-bit delta-sigma
ADCs.
Figure 9. MAX11905 FFT (fSAMPLE = 1Msps, fIN = 10kHz)
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Maxim Integrated │ 24
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Figure 10. MAX11905 FFT (fSAMPLE = 1.6Msps, fIN = 10kHz)
Figure 11. MAX11905 Output Data Histogram (Inputs Shorted, Averaging = 1, fSAMPLE = 1Msps)
www.maximintegrated.com
Maxim Integrated │ 25
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Figure 12. MAX11905 Output Data Histogram (Inputs Shorted, Averaging = 16, fSAMPLE = 1Msps)
Figure 13. MAX11905 Output Data Histogram (Inputs Shorted, Averaging = 64, fSAMPLE = 1Msps)
www.maximintegrated.com
Maxim Integrated │ 26
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
3.2V to 12.6V
3V
MAX6126
4.7nF
C0G
GND
3V
499Ω
0.1%
1kΩ
0.1%
0V
-3V
1kΩ
1.5V
3.3V
0V
VS+
6VP-P + 0VDC
10µF
3V
+5V
+
-
10Ω
AIN+ VREF
OUT+
1.5V
VOCM
MAX44206
2.2nF
0.1µF
2.2nF
IN
OUT
10Ω
OUT-
1kΩ
AVDD
MAX11905
AIN-
GND
ADC INPUT FILTER
VS-
1kΩ
0.1%
-5V
3V
499Ω
0.1%
1.5V
0V
4.7nF
C0G
Figure 14. MAX44206 Used to Drive a Single-Ended Input into a Differential, 20-Bit SAR ADC
www.maximintegrated.com
Maxim Integrated │ 27
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Ordering Information
TEMP RANGE
PINPACKAGE
TOP
MARK
-40°C to +125°C
8 µMAX-EP*
+AACT
PART
MAX44206AUA+
Package Information
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Chip Information
PROCESS: BiCMOS
www.maximintegrated.com
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 µMAX-EP
U8E+2
21-0107
90-0145
Maxim Integrated │ 28
MAX44206
180MHz, Low-Noise, Low-Distortion, Fully
Differential Op Amp/ADC Driver
Revision History
REVISION
NUMBER
REVISION
DATE
0
11/14
DESCRIPTION
Initial release
PAGES
CHANGED
—
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2014 Maxim Integrated Products, Inc. │ 29
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