19-3969; Rev 1; 3/07
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
*See the Ultrasound-Specific IMD3 Specification in the
Applications Information section.
GND
GND
VCC
OUT3-
OUT3+
VCC
OUT2-
OUT2+
GND
OUT1-
VCC
OUT1+
OUT4-
GND
39
22
GND
GND
40
21
GND
VCC
41
20
VCC
D2
42
19
D0
PD
43
18
D1
VCC
44
17
VCC
VCC
45
16
VCC
GND
46
15
GND
ZF1
47
14
INB4
IN1
48
13
INC4
MAX2034
1
2
3
4
5
6
7
8
9
10 11 12
IN4
**EP = Exposed paddle.
+Denotes lead-free package.
T = Tape-and-reel package.
23
ZF4
48 Thin QFN-EP**
T4877-4
(7mm x 7mm)
24
38
INB3
48 Thin QFN-EP**
T4877-4
(7mm x 7mm)
37
VCC
INC3
MAX2034CTM-T 0°C to +70°C
48 Thin QFN-EP**
T4877-4
(7mm x 7mm)
OUT4+
GND
IN3
MAX2034CTM+T 0°C to +70°C
48 Thin QFN-EP**
T4877-4
(7mm x 7mm)
36 35 34 33 32 31 30 29 28 27 26 25
ZF3
0°C to +70°C
PKG
CODE
TOP VIEW
INB2
MAX2034CTM
0°C to +70°C
PINPACKAGE
Pin Configuration
IN2
MAX2034CTM+
TEMP
RANGE
Sonar Signal Amplification
INC2
PART
Ultrasound Imaging
ZF2
Ordering Information
Applications
INB1
The MAX2034 has excellent dynamic and linearity performance characteristics optimized for all ultrasoundimaging modalities including second harmonic 2D
imaging and continuous wave Doppler. The device
achieves a second harmonic distortion of -68dBc at
VOUT = 1VP-P and fIN = 5MHz, and an ultrasound-specific* two-tone third-order intermodulation distortion performance of -55dBc at VOUT = 1VP-P and fIN = 5MHz.
The MAX2034 is also optimized for quick overload
recovery for operation under the large input signal conditions typically found in ultrasound input-buffer imaging applications.
The MAX2034 is available in a 48-pin thin QFN package with an exposed paddle. Electrical performance is
guaranteed over a 0°C to +70°C temperature range.
♦ High-Level Integration of 4 Channels
♦ Digitally Programmable Input Impedance (RIN) of
50Ω, 100Ω, 200Ω, and 1kΩ
♦ Integrated Input Clamp
♦ Integrated Input-Damping Capacitor
♦ Ultra-Low 2.2dB Noise Figure at RS = RIN = 200Ω
♦ 70MHz, -3dB Bandwidth
♦ Low 58mW/Channel Power Dissipation
♦ HD2 of -68dBc at VOUT = 1VP-P and fIN = 5MHz for
Exceptional Second Harmonic Imaging
Performance
♦ Two-Tone Ultrasound-Specific* IMD3 of -55dBc at
VOUT = 1VP-P and fIN = 5MHz for Exceptional
PW/CW Doppler Performance
♦ Quick Large-Signal Overload Recovery
♦ Single +5V Supply Operation
♦ Sleep Mode
INC1
The MAX2034 four-channel, low-power, ultra-low-noise
preamplifier is designed for ultrasound and medical
instrumentation applications. Each low-noise amplifier
has a single-ended input, differential output, a highly
accurate 19dB fixed gain, and a wide -3dB bandwidth
of 70MHz. The high-gain accuracy of the amplifier
allows for exceptional channel-to-channel gain matching, which is necessary for high-performance ultrasound-imaging applications. The MAX2034 also
includes an on-chip programmable input impedance
feature that allows the device to be compatible with a
variety of common source impedances ranging from
50Ω to 1kΩ. The input impedance of each amplifier
uses a feedback topology for active impedance matching. The active input impedance matching feature
achieves an exceptionally low 2.2dB noise figure with a
source and input impedance of 200Ω.
Features
THIN QFN
Typical Application Circuit appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX2034
General Description
MAX2034
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
ABSOLUTE MAXIMUM RATINGS
VCC to GND ...........................................................-0.3V to +5.5V
Any Other Pins to GND...............................-0.3V to (VCC + 0.3V)
IN_ to INB_ ..................................................................-2V to +2V
INC_ to GND .....................................................-24mA to +24mA
Continuous Power Dissipation (TA = +70°C)
48-Pin TQFN (derated 40mW/°C above +70°C) ........3200mW
Operating Temperature Range...............................0°C to +70°C
Junction Temperature ......................................................+150°C
θJC ...................................................................................0.8°C/W
θJA ....................................................................................25°C/W
Storage Temperature Range .............................-40°C to +150°C
Lead Temperature (soldering, 10s) .................................+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
(MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, no input signal applied between IN1–IN4 and GND, TA = 0°C to +70°C.
Typical values are at VCC = +5.0V and TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
Supply Voltage
Total Supply Current
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
4.75
5.0
5.25
V
ICC
Normal mode (PD = 0), no signals applied, see
the Typical Operating Characteristics for ICC as
a function of input signal
46.5
54.5
ICC,PD
Sleep mode (PD = 1), VIN_ = 112mVP-P at 5MHz
0.8
4
VCC
mA
LOGIC INPUTS (PD, D2, D1, D0)
Input High Voltage
VIH
Input Low Voltage
VIL
4.0
1.0
V
V
Input Current with Logic-High
IIH
1
µA
Input Current with Logic-Low
IIL
1
µA
AC ELECTRICAL CHARACTERISTICS
(MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω),
signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω
between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C. Typical values are at VCC = 5.0V and TA =
+25°C, unless otherwise noted.) (Note 1)
PARAMETER
Input Resistance
SYMBOL
RIN
CONDITIONS
MIN
D2/D1/D0 = 0/0/0
53
D2/D1/D0 = 0/0/1
105
D2/D1/D0 = 0/1/0
206
D2/D1/D0 = 0/1/1
870
Typical Input Resistance Variation
from Nominal Programmed
CIN
Gain
AV
Part-to-Part Gain Variation from
Nominal
Slew Rate
2
MAX
(OUT_+ - OUT_-) / IN_
TA = +25oC, RL = 200Ω ±10%
f-3dB
D2/D1/D0 = 0/0/0, (50Ω input impedance),
VOUT = 0.2VP-P
0
UNITS
Ω
±1
Input Capacitance
-3dB Small-Signal Gain
Bandwidth
TYP
%
40
pF
19
dB
±0.1
±0.5
dB
70
MHz
280
V/µs
_______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
(MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω),
signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω
between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C. Typical values are at VCC = 5.0V and TA =
+25°C, unless otherwise noted.) (Note 1)
PARAMETER
Noise Figure
SYMBOL
NF
CONDITIONS
MIN
TYP
RS = RIN = 50Ω
4.1
RS = RIN = 100Ω
2.9
RS = RIN = 200Ω
2.2
MAX
UNITS
dB
RS = RIN = 1000Ω
1.4
Input-Referred Noise Voltage
D2 = 1 (high input impedance), fIN_ = 5MHz
0.87
nV/√Hz
Input-Referred Noise Current
D2 = 1 (high input impedance), fIN_ = 5MHz
2.1
pA/√Hz
Second Harmonic
HD2
Third Harmonic
HD3
Two-Tone Intermodulation
Distortion (Note 2)
fIN_ = 5MHz, VOUT = 1VP-P differential
-50
-68
fIN_ = 10MHz, VOUT = 1VP-P differential
-66
fIN_ = 5MHz, VOUT = 1VP-P differential
-50
fIN_ = 10MHz, VOUT = 1VP-P differential
-44
4.99MHz tone relative to the second tone at
5.01MHz, which is 25dB lower than the first tone
at 5.00MHz, VOUT = 1VP-P differential
-45
dBc
dBc
-55
dBc
IMD3
7.49MHz tone relative to the second tone at
7.51MHz, which is 25dB lower than the first tone
at 7.50MHz, VOUT = 1VP-P differential
-52
Maximum Output Signal
Amplitude
Differential output
4.4
Gain Compression
Gain at VIN_ = 112mVP-P relative to gain at
VIN_ = 550mVP-P
0.5
Output Common-Mode Level
VP-P
3
dB
2.45
V
5.3
Ω
±1.5
deg
66
dB
Supply current settles to 90% of nominal sleepmode current ICC,PD
0.3
ms
VOUT settles to 90% of final 1VP-P output
0.3
ms
Output Impedance
Single-ended
Phase Matching Between
Channels
Phase difference between channels with VIN_ =
195mV peak (-3dB full scale), fIN_ = 10MHz
Channel-to-Channel Crosstalk
fIN_ = 10MHz, VOUT = 1VP-P, adjacent channels
Switch Time from Normal to Sleep
Mode
Switch Time from Sleep to Normal
Mode
50
Note 1: Min and max limits at TA = +25°C and +70°C are guaranteed by design, characterization, and/or production test.
Note 2: See the Ultrasound-Specific IMD3 Specification in the Applications Information section.
_______________________________________________________________________________________
3
MAX2034
AC ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω),
signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω
between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C, unless otherwise specified.)
SMALL-SIGNAL BANDWIDTH
vs. FREQUENCY
15
GAIN (dB)
GAIN (dB)
10
10
5
5
5
0
0
0
-5
-5
0.1
1
10
100
1
10
100
1000
0.1
10
100
1000
FREQUENCY (MHz)
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
COMPLEX INPUT IMPEDANCE MAGNITUDE
vs. FREQUENCY
COMPLEX INPUT IMPEDANCE MAGNITUDE
vs. FREQUENCY
0
120
55
110
45
90
40
80
35
70
60
30
-5
0.1
1
10
100
100
1000
0
10
FREQUENCY (MHz)
20
30
40
0
50
5
COMPLEX INPUT IMPEDANCE MAGNITUDE
vs. FREQUENCY
COMPLEX INPUT IMPEDANCE MAGNITUDE
vs. FREQUENCY
1150
MAX2034 toc07
D2/D1/D0 = 0/1/0
RIN = 200Ω
D2/D1/D0 = 0/1/1
RIN = 1kΩ
1000
850
IZINI
225
200
15
20
25
30
HARMONIC DISTORTION
vs. FREQUENCY
-20
HARMONIC DISTORTION (dBc)
275
10
FREQUENCY (MHz)
FREQUENCY (MHz)
700
550
175
400
150
250
VOUT = 1VP-P DIFFERENTIAL
RL = 200Ω
-30
-40
THIRD HARMONIC
-50
-60
-70
125
MAX2034 toc09
5
60
50
D2/D1/D0 = 0/0/1
RIN = 100Ω
130
IZINI
IZINI
15
10
D2/D1/D0 = 0/0/0
RIN = 50Ω
65
140
MAX2034 toc05
MAX2034 toc04
70
MAX2034 toc06
FREQUENCY (MHz)
VIN = 500mVP-P
RIN = 50Ω
250
1
FREQUENCY (MHz)
25
20
-5
0.1
1000
MAX2034 toc08
GAIN (dB)
10
VIN_ = 500mVP-P,
RIN = 200Ω
20
15
15
GAIN (dB)
VIN = 112mVP-P
RIN = 50Ω
20
25
MAX2034 toc02
VIN_ = 112mVP-P,
RIN = 200Ω
20
25
MAX2034 toc01
25
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
MAX2034 toc03
SMALL-SIGNAL BANDWIDTH
vs. FREQUENCY
IZINI
MAX2034
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
SECOND HARMONIC
100
100
0
0
4
8
12
FREQUENCY (MHz)
4
16
20
4
8
12
FREQUENCY (MHz)
16
20
-80
0
5
10
15
20
FREQUENCY (MHz)
_______________________________________________________________________________________
25
30
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
-10
-30
-40
-50
-60
-70
5
10
15
20
25
3
VIN = 200mVP-P
2
VIN = 112mVP-P
1
SMALL-SIGNAL
NOISE FIGURE
0.1
1
10
100
FREQUENCY (MHz)
OFFSET FREQUENCY (kHz)
GAIN-ERROR HISTOGRAM
CHANNEL-TO-CHANNEL CROSSTALK
vs. FREQUENCY
SAMPLE SIZE = 243 UNITS
fIN_ = 5MHz, VIN = 112mVP-P
40
-30
VOUT = 1VP-P DIFFERENTIAL
RL = 200Ω
ADJACENT CHANNELS
-40
-50
CROSSTALK (dB)
35
% OF UNITS
VIN = 300mVP-P
30
MAX2034 toc12
45
4
0
0
50
RIN = 200Ω
RL = 200Ω
fIN_ = 5MHz
5
MAX2034 toc13
IMD3 (dBc)
-20
6
MAX2034 toc11
VOUT = 1VP-P DIFFERENTIAL
RL = 200Ω
LARGE-SIGNAL NOISE FIGURE
vs. OFFSET FREQUENCY
LARGE-SIGNAL NOISE FIGURE (dB)
0
MAX2034 toc10
TWO-TONE ULTRASOUND-SPECIFIC IMD3
vs. FREQUENCY
30
25
20
15
-60
-70
-80
10
-90
5
-100
1
0.18
0.14
0.10
0.06
0.02
-0.04
-0.08
-0.12
-0.16
-0.20
0
10
100
FREQUENCY (MHz)
GAIN ERROR (dB)
SUPPLY CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
MAX2034 toc14
ALL CHANNELS ACTIVE
110
SUPPLY CURRENT (mA)
LARGE-SIGNAL RECOVERY
MAX2034 toc15
130
fIN_ = 5MHz
INPUT IN_
500mV/div
90
RL = 200Ω
DIFFERENTIAL
OUTPUT
OUT_+ - OUT_2.0V/div
70
NO LOAD
50
30
0
1
2
3
4
400ns/div
DIFFERENTIAL OUTPUT VOLTAGE (VP-P)
_______________________________________________________________________________________
5
MAX2034
Typical Operating Characteristics (continued)
(MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω),
signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω
between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C, unless otherwise specified.)
MAX2034
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
Typical Operating Characteristics (continued)
(MAX2034 Typical Application Circuit, VCC = +4.75V to +5.25V, source impedance RS = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (RIN = 200Ω),
signal AC-coupled to IN_, INB_ is AC grounded, VOUT is the differential output between OUT_+ and OUT_-, fIN_ = 5MHz, RL = 200Ω
between the differential outputs, CL = 20pF from each output to ground, TA = 0°C to +70°C, unless otherwise specified.)
CLAMP SYMMETRY UNDER
TRANSMIT RECOVERY
LARGE-SIGNAL RECOVERY
MAX2034 toc17
MAX2034 toc16
fIN_ = 5MHz
fIN_ = 10MHz
INPUT IN_
500mV/div
SINGLE-ENDED
OUTPUT OUT_+
1V/div
DIFFERENTIAL
OUTPUT
OUT_+ - OUT_2.0V/div
SINGLE-ENDED
OUTPUT OUT_1V/div
200ns/div
400ns/div
Pin Description
PIN
NAME
1
INC1
2
INB1
Channel 1 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin.
3
ZF2
Channel 2 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor.
4
IN2
Channel 2 LNA Analog Input. Single-ended input for channel 2 amplifier. Connect the analog input to
the source circuit through a series capacitor.
5
INC2
Channel 2 Analog Input Clamp. Input port to the integrated clamping diodes.
6
INB2
Channel 2 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin.
7
ZF3
Channel 3 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor.
8
IN3
Channel 3 LNA Analog Input. Single-ended input for channel 3 amplifier. Connect the analog input to
the source circuit through a series capacitor.
9
INC3
Channel 3 Analog Input Clamp. Input port to the integrated clamping diodes.
10
INB3
Channel 3 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin.
11
ZF4
Channel 4 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor.
12
IN4
Channel 4 LNA Analog Input. Single-ended input for channel 4 amplifier. Connect the analog input to
the source circuit through a series capacitor.
13
INC4
Channel 4 Analog Input Clamp. Input port to the integrated clamping diodes.
14
INB4
Channel 4 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin.
15, 21, 22, 25,
26, 33, 37, 39,
40, 46
GND
Ground
16, 17, 20, 27,
30, 34, 38, 41,
44, 45
VCC
5V Power Supply. Supply for the four LNAs. Bypass each VCC supply with a 100nF capacitor as
close as possible to the pin.
6
FUNCTION
Channel 1 Analog Input Clamp. Input port to the integrated clamping diodes.
_______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
PIN
NAME
18, 19, 42
D1, D0, D2
FUNCTION
Digitally Programmable Inputs. Programs the input impedance of each amplifier. See Table 1 on
input impedance programming information.
23
OUT4-
Channel 4 LNA Analog Inverting Output
24
OUT4+
Channel 4 LNA Analog Noninverting Output
28
OUT3-
Channel 3 LNA Analog Inverting Output
29
OUT3+
Channel 3 LNA Analog Noninverting Output
31
OUT2-
Channel 2 LNA Analog Inverting Output
32
OUT2+
Channel 2 LNA Analog Noninverting Output
35
OUT1-
Channel 1 LNA Analog Inverting Output
36
OUT1+
Channel 1 LNA Analog Noninverting Output
43
PD
Power-Down. Drive PD high to put the device in sleep mode. Drive PD low for normal mode.
47
ZF1
Channel 1 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor.
48
IN1
Channel 1 LNA Analog Input. Single-ended input for channel 1 amplifier. Connect the analog input to
the source circuit through a series capacitor.
EP
GND
Exposed Paddle. Solder the exposed paddle to the ground plane using multiple vias.
Detailed Description
The MAX2034 is a four-channel, ultra-low-noise preamplifier. Each amplifier features single-ended inputs, differential outputs, and provides an accurate fixed gain of
19dB with a wide -3dB bandwidth of 70MHz. The highgain accuracy of the amplifier allows for exceptional
channel-to-channel gain matching, which is necessary
for high-performance ultrasound-imaging applications.
The device has an exceptionally low noise figure, making
it ideal for use in ultrasound front-end designs. Noise figure is typically 2.2dB for a source impedance and programmed input impedance of 200Ω.
The MAX2034 is optimized for excellent dynamic range
and linearity performance characteristics, making it ideal
for ultrasound-imaging modalities including second harmonic 2D imaging and continuous wave Doppler. The
device achieves an HD2 of -68dBc at VOUT = 1VP-P and
fIN_ = 5MHz, and an ultrasound-specific two-tone IMD3
performance of -55dBc at V OUT = 1VP-P and f IN_ =
5MHz. See the Ultrasound-Specific IMD3 Specification in
the Applications Information section.
amplifier, A, being defined with a differential output. For
common input impedances, the internal digitally programmed impedances can be used (see Table 1). For
other input impedances, program the impedance for
external resistor operation, and then use an externally
supplied resistor to set the input impedance according
to the above formula.
The gain and input impedance of the MAX2034 vs. frequency are shown in the Typical Operating Characteristics. Both gain and input impedance are well
behaved, with no peaking characteristics. This allows
the device to be used with a variety of input networks,
with no requirement for series ferrite beads or shunt
capacitors for stability control.
Table 1. Digitally Programmable Input
Impedance
D2
D1
D0
0
0
0
RIN (Ω)
50
Active Impedance Matching
0
0
1
100
To provide exceptional noise-figure characteristics, the
input impedance of each amplifier uses a feedback
topology for active impedance matching. A feedback
resistor of the value (1 + (A / 2)) x RS is added between
the inverting output of the amplifier to the input. The
input impedance is the feedback resistor, ZF, divided
by 1 + (A / 2). The factor of two is due to the gain of the
0
1
0
200
0
1
1
1k
1
0
0
1
0
1
1
1
0
1
1
1
Defined by external resistor
_______________________________________________________________________________________
7
MAX2034
Pin Description (continued)
MAX2034
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
Functional Diagram
D2/D1/D0
PD
ZF1
IN1
OUT1-
INC1
OUT1+
INB1
MAX2034
Digitally Programmable Input Impedance
The MAX2034 features an on-chip digitally programmable input impedance, which makes the part compatible
with a variety of source impedances ranging from 50Ω
to 1kΩ. The input impedance can be programmed for
50Ω, 100Ω, 200Ω, or 1kΩ through the digital inputs D2,
D1, and D0. See Table 1 for programming details. In
addition to these fixed values, virtually any other input
impedance can be supported by using an off-chip
external feedback resistor, RF. To utilize this feature, set
D2, D1, and D0 to any of the four external resistor-controlled states shown in Table 1. The value of the off-chip
feedback resistor can be determined by using the following relationship:
RF = (1 + (A / 2)) x RS
where RS is the source impedance, and A is the gain of
the amplifier (A = 9) defined with a differential output.
Noise Figure
ZF2
IN2
OUT2-
INC2
OUT2+
INB2
The MAX2034 is designed to provide maximum input
sensitivity with its exceptionally low noise figure. The
input active devices are selected for very low equivalent input noise voltage and current, and they have
been optimized for source impedances from 50Ω to
1000Ω. Additionally, the noise contribution of the
matching resistor is effectively divided by 1 + (A / 2).
Using this scheme, typical noise figure of the amplifier
is approximately 2.2dB for RIN = RS = 200Ω. Table 2
illustrates the noise figure for other input impedances.
Table 2. Noise Figure vs. Source and
Input Impedances
ZF3
Rs (Ω)
IN3
OUT3-
INC3
OUT3+
RIN (Ω)
NF (dB)
50
50
4.1
100
100
2.9
200
200
2.2
1000
1000
1.4
INB3
Input Clamp
ZF4
IN4
OUT4-
INC4
OUT4+
INB4
8
The MAX2034 includes configurable integrated inputclamping diodes. The diodes are clamped to ground at
±275mV. The input-clamping diodes can be used to
prevent large transmit signals from overdriving the inputs
of the amplifiers. Overdriving the inputs could possibly
place charge on the input-coupling capacitor, causing
longer transmit overload recovery times. Input signals
are AC-coupled to the single-ended inputs IN1–IN4, but
are clamped with the INC1–INC4 inputs. See the Typical
Application Circuit. If external clamping devices are preferred, simply leave INC1–INC4 unconnected.
_______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
Overload Recovery
The device is also optimized for quick overload recovery for operation under the large input signal conditions
that are typically found in ultrasound input-buffer imaging applications. Internal signal clipping is symmetrical.
Input overloads can be prevented with the input-clamping diodes. See the Typical Operating Characteristics
that illustrate the rapid recovery time from a transmitrelated overload.
Sleep Mode
The sleep mode function allows the MAX2034 to be
configured in a low-power state when the amplifiers are
not being used. In sleep mode, all amplifiers are powered down, the total supply current of the device
reduces to 0.8mA, and the input impedance of each
amplifier is set at high impedance. Drive the PD input
high to activate sleep mode. For normal operation,
drive the PD input low.
The Typical Application Circuit illustrates these coupling capacitors. If a ground-referenced current-limiting
stage precedes the MAX2034 inputs, its output can be
connected to the integrated clamping diodes on pins
INC1–INC4 to facilitate very rapid recovery from transient overloads associated with transmitter operation in
ultrasound applications.
Analog Output Coupling
The differential outputs of the MAX2034 are capable of
driving a differential load impedance of 200Ω or
greater. The differential output has a common-mode
bias of approximately 2.45V. AC-couple these differential outputs if the next stage has a different commonmode input range.
Board Layout
The pin configuration of the MAX2034 is optimized to
facilitate a very compact physical layout of the device
and its associated discrete components. A typical
application for this device might incorporate several
devices in close proximity to handle multiple channels
of signal processing.
The exposed paddle (EP) of the MAX2034’s thin QFNEP package provides a low thermal-resistance path to
the die. It is important that the PC board on which the
MAX2034 is mounted be designed to conduct heat
from the EP. In addition, provide the EP with a lowinductance path to electrical ground. The EP MUST be
soldered to a ground plane on the PC board, either
directly or through an array of plated via holes.
Applications Information
Analog Input Coupling
AC-couple to ground the analog bypass input by connecting a 0.1µF capacitor at the INB1–INB4 input to
GND (0.1µF recommended). Since the amplifiers are
designed with a differential input stage, bypassing the
INB1–INB4 inputs configures the MAX2034 for singleended inputs at IN1–IN4.
Connect the IN1–IN4 inputs to their source circuits
through 0.1µF series capacitors. Connect the feedback
ports ZF1–ZF4 to the source circuits through 0.018µF
capacitors. (These capacitors will be 1/(5.5) as large as
the input-coupling capacitors. This equalizes the highpass filter characteristic of both the input and feedback
input ports, due to the feedback resistance related by a
factor of 1/(5.5) to the input impedance.)
Note that the active input circuitry of the MAX2034 is
stable, and does not require external ferrite beads or
shunt capacitors to achieve high-frequency stability.
-25dB
ULTRASOUND IMD3
F1 - (F2 - F1)
F1
F2
F2 + (F2 - F1)
Figure 1. Ultrasound IMD3 Measurement Technique
_______________________________________________________________________________________
9
MAX2034
Integrated Input Damping Capacitor
At high frequencies, gain peaking can occur due to an
active input termination becoming less effective when
the gain rolls off. Although an external shunting capacitor can be used to mitigate this effect, different input
impedance modes require different capacitor values.
The MAX2034 integrates a damping capacitor for each
of the four programmed input impedance modes. When
the input impedance is programmed by applying the
appropriate D2/D1/D0, an optimal capacitor value is
also chosen for the particular input impedance mode,
eliminating the need for external capacitors.
MAX2034
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
D2/D1/D0
PD
+V
ZF_
18nF
100nF
100nF
IN_
OUT_100nF
INC_
OUT_+
ONE CHANNEL
INB_
MAX2034
-V
100nF
Figure 2. Typical Single-Channel Ultrasound Application Circuit
Ultrasound-Specific IMD3 Specification
Unlike typical communications specs, the two input
tones are not equal in magnitude for the ultrasoundspecific IMD3 two-tone specification. In this measurement, F1 represents reflections from tissue and F2
represents reflections from blood. The latter reflections
are typically 25dB lower in magnitude, and hence the
measurement is defined with one input tone 25dB lower
than the other. The IMD3 product of interest (F1 - (F2 F1)) presents itself as an undesired Doppler error signal in ultrasound applications. See Figure 1.
10
______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
+5V
100nF
100nF
48
47
46
45
44
42
41
39
GND
GND
40
VCC
GND
D2
43
VCC
VCC
PD
VCC
GND
IN1
18nF
ZF1
100nF
37
38
INC1
RS = 200Ω
INB3
ZF4
100nF
18nF
30
29
8
9
28
EXPOSED PADDLE
27
10
26
11
25
12
100nF
OUT1-
100nF
VCC
GND
100nF
OUT2+
100nF
OUT2-
100nF
VCC
OUT3+
100nF
OUT3-
100nF
100nF
VCC
GND
100nF
GND
13 14 15 16 17 18 19 20 21 22 23 24
INC4
100nF
IN4
MAX2034
7
100nF
OUT4-
INC3
31
OUT1+
OUT4+
100nF
IN3
6
GND
18nF
32
GND
100nF
5
D0
ZF3
33
VCC
INB2
4
D1
RS = 200Ω
34
VCC
INC2
3
VCC
100nF
IN2
GND
ZF2
18nF
35
2
INB4
INB1
100nF
RS = 200Ω
36
1
RS = 200Ω
100nF
100nF
+5V
100nF
100nF
+5V
______________________________________________________________________________________
11
MAX2034
Typical 200Ω Application Circuit
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
E
DETAIL A
32, 44, 48L QFN.EPS
MAX2034
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
(NE-1) X e
E/2
k
e
D/2
CL
(ND-1) X e
D
D2
D2/2
b
L
E2/2
DETAIL B
e
E2
CL
L
L1
CL
k
CL
L
L
e
A1
A2
e
A
PACKAGE OUTLINE
32, 44, 48, 56L THIN QFN, 7x7x0.8mm
21-0144
12
______________________________________________________________________________________
E
1
2
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
PACKAGE OUTLINE
32, 44, 48, 56L THIN QFN, 7x7x0.8mm
21-0144
E
2
2
Revision History
Pages changed at Rev 1: 1, 3, 4, 11, 12
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13
© 2007 Maxim Integrated Products
Springer
is a registered trademark of Maxim Integrated Products, Inc.
MAX2034
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
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