MAX2034CTM-T [MAXIM]
Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance; 四通道，超低噪声放大器，具有数字可编程输入阻抗
| 型号： | MAX2034CTM-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Quad-Channel, Ultra-Low-Noise Amplifier with Digitally Programmable Input Impedance |
| 文件： | 总13页 (文件大小：345K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3969; Rev 1; 3/07
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
General Description
Features
♦ High-Level Integration of 4 Channels
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 match-
ing, which is necessary for high-performance ultra-
sound-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 match-
ing. The active input impedance matching feature
achieves an exceptionally low 2.2dB noise figure with a
source and input impedance of 200Ω.
♦ Digitally Programmable Input Impedance (R ) of
50Ω, 100Ω, 200Ω, and 1kΩ
♦ Integrated Input Clamp
IN
♦ Integrated Input-Damping Capacitor
♦ Ultra-Low 2.2dB Noise Figure at R = R = 200Ω
S
IN
♦ 70MHz, -3dB Bandwidth
♦ Low 58mW/Channel Power Dissipation
♦ HD2 of -68dBc at V = 1V and f = 5MHz for
OUT
P-P
IN
Exceptional Second Harmonic Imaging
Performance
♦ Two-Tone Ultrasound-Specific* IMD3 of -55dBc at
V
= 1V
and f = 5MHz for Exceptional
P-P IN
OUT
PW/CW Doppler Performance
♦ Quick Large-Signal Overload Recovery
♦ Single +5V Supply Operation
♦ Sleep Mode
The MAX2034 has excellent dynamic and linearity per-
formance characteristics optimized for all ultrasound-
imaging modalities including second harmonic 2D
imaging and continuous wave Doppler. The device
achieves a second harmonic distortion of -68dBc at
Applications
Ultrasound Imaging
V
OUT
= 1V and f = 5MHz, and an ultrasound-spe-
P-P IN
Sonar Signal Amplification
cific* two-tone third-order intermodulation distortion per-
formance of -55dBc at V = 1V and f = 5MHz.
OUT
P-P
IN
The MAX2034 is also optimized for quick overload
recovery for operation under the large input signal con-
ditions typically found in ultrasound input-buffer imag-
ing applications.
Pin Configuration
TOP VIEW
The MAX2034 is available in a 48-pin thin QFN pack-
age with an exposed paddle. Electrical performance is
guaranteed over a 0°C to +70°C temperature range.
35 34 33 32 31 30 29 28 27
36
26
25
OUT4+
OUT4-
GND
37
38
24
23
V
CC
Ordering Information
22 GND
21 GND
GND 39
GND 40
TEMP
PIN-
PKG
PART
20
V
CC
V
41
42
RANGE
PACKAGE
CODE
CC
D2
19 D0
18 D1
48 Thin QFN-EP**
(7mm x 7mm)
MAX2034CTM+ 0°C to +70°C
MAX2034CTM 0°C to +70°C
T4877-4
T4877-4
T4877-4
T4877-4
MAX2034
PD 43
17
16
15
V
CC
V
CC
V
44
45
46
47
48
CC
CC
48 Thin QFN-EP**
(7mm x 7mm)
V
GND
GND
ZF1
IN1
48 Thin QFN-EP**
(7mm x 7mm)
14 INB4
13
MAX2034CTM+T 0°C to +70°C
MAX2034CTM-T 0°C to +70°C
INC4
48 Thin QFN-EP**
(7mm x 7mm)
2
3
4
5
6
7
8
9
10
1
11
12
**EP = Exposed paddle.
+Denotes lead-free package.
T = Tape-and-reel package.
THIN QFN
*See the Ultrasound-Specific IMD3 Specification in the
Applications Information section.
Typical Application Circuit appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
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.
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
ABSOLUTE MAXIMUM RATINGS
V
to GND...........................................................-0.3V to +5.5V
Operating Temperature Range...............................0°C to +70°C
Junction Temperature......................................................+150°C
CC
Any Other Pins to GND...............................-0.3V to (V
+ 0.3V)
CC
IN_ to INB_ ..................................................................-2V to +2V
INC_ to GND .....................................................-24mA to +24mA
θ
θ
...................................................................................0.8°C/W
....................................................................................25°C/W
JC
JA
Continuous Power Dissipation (T = +70°C)
A
48-Pin TQFN (derated 40mW/°C above +70°C)........3200mW
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, V
= +4.75V to +5.25V, no input signal applied between IN1–IN4 and GND, T = 0°C to +70°C.
CC
A
Typical values are at V = +5.0V and T = +25°C, unless otherwise noted.) (Note 1)
CC
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX UNITS
Supply Voltage
V
4.75
5.0
5.25
54.5
4
V
CC
Normal mode (PD = 0), no signals applied, see
I
the Typical Operating Characteristics for I
as
46.5
0.8
CC
CC
Total Supply Current
mA
a function of input signal
I
Sleep mode (PD = 1), V
= 112mV
at 5MHz
CC,PD
IN_
P-P
LOGIC INPUTS (PD, D2, D1, D0)
Input High Voltage
V
4.0
V
V
IH
Input Low Voltage
V
1.0
1
IL
Input Current with Logic-High
Input Current with Logic-Low
I
µA
µA
IH
I
1
IL
AC ELECTRICAL CHARACTERISTICS
(MAX2034 Typical Application Circuit, V = +4.75V to +5.25V, source impedance R = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (R = 200Ω),
CC
S
IN
signal AC-coupled to IN_, INB_ is AC grounded, V
is the differential output between OUT_+ and OUT_-, f
= 5MHz, R = 200Ω
IN_ L
OUT
between the differential outputs, C = 20pF from each output to ground, T = 0°C to +70°C. Typical values are at V
= 5.0V and T =
A
L
A
CC
+25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
53
MAX UNITS
D2/D1/D0 = 0/0/0
D2/D1/D0 = 0/0/1
D2/D1/D0 = 0/1/0
D2/D1/D0 = 0/1/1
105
206
870
Input Resistance
R
Ω
IN
Typical Input Resistance Variation
from Nominal Programmed
1
%
Input Capacitance
Gain
C
40
19
pF
dB
IN
A
(OUT_+ - OUT_-) / IN_
= +25oC, R = 200Ω 10%
V
Part-to-Part Gain Variation from
Nominal
T
A
0
0.1
0.5
dB
L
-3dB Small-Signal Gain
Bandwidth
D2/D1/D0 = 0/0/0, (50Ω input impedance),
= 0.2V
f
70
MHz
V/µs
-3dB
V
OUT
P-P
Slew Rate
280
2
_______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2034 Typical Application Circuit, V = +4.75V to +5.25V, source impedance R = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (R = 200Ω),
CC
S
IN
signal AC-coupled to IN_, INB_ is AC grounded, V
is the differential output between OUT_+ and OUT_-, f
= 5MHz, R = 200Ω
IN_ L
OUT
between the differential outputs, C = 20pF from each output to ground, T = 0°C to +70°C. Typical values are at V
= 5.0V and T =
A
L
A
CC
+25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
4.1
2.9
2.2
1.4
0.87
2.1
-68
-66
-50
-44
MAX UNITS
R = R = 50Ω
S
IN
R = R = 100Ω
S
IN
Noise Figure
NF
dB
R = R = 200Ω
S
IN
R = R = 1000Ω
S
IN
Input-Referred Noise Voltage
Input-Referred Noise Current
D2 = 1 (high input impedance), f
D2 = 1 (high input impedance), f
= 5MHz
= 5MHz
nV/√Hz
pA/√Hz
IN_
IN_
f
f
f
f
= 5MHz, V
= 1V
differential
-50
-45
IN_
IN_
IN_
IN_
OUT
P-P
Second Harmonic
Third Harmonic
HD2
HD3
dBc
dBc
= 10MHz, V
= 1V
differential
OUT
P-P
= 5MHz, V
= 1V
differential
differential
OUT
P-P
= 10MHz, V
= 1V
P-P
OUT
4.99MHz tone relative to the second tone at
5.01MHz, which is 25dB lower than the first tone
-55
-52
at 5.00MHz, V
= 1V
differential
P-P
OUT
Two-Tone Intermodulation
Distortion (Note 2)
IMD3
dBc
7.49MHz tone relative to the second tone at
7.51MHz, which is 25dB lower than the first tone
at 7.50MHz, V
= 1V
differential
P-P
OUT
Maximum Output Signal
Amplitude
Differential output
Gain at V = 112mV
4.4
0.5
V
P-P
relative to gain at
P-P
IN_
Gain Compression
3
dB
V
= 550mV
P-P
IN_
Output Common-Mode Level
Output Impedance
2.45
5.3
V
Single-ended
Phase difference between channels with V
Ω
Phase Matching Between
Channels
=
IN_
1.5
66
deg
dB
195mV peak (-3dB full scale), f
= 10MHz
IN_
Channel-to-Channel Crosstalk
f
= 10MHz, V
= 1V adjacent channels
P-P,
50
IN_
OUT
Switch Time from Normal to Sleep
Mode
Supply current settles to 90% of nominal sleep-
mode current I
0.3
ms
CC,PD
Switch Time from Sleep to Normal
Mode
V
settles to 90% of final 1V
output
0.3
ms
OUT
P-P
Note 1: Min and max limits at T = +25°C and +70°C are guaranteed by design, characterization, and/or production test.
A
Note 2: See the Ultrasound-Specific IMD3 Specification in the Applications Information section.
_______________________________________________________________________________________
3
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
Typical Operating Characteristics
(MAX2034 Typical Application Circuit, V = +4.75V to +5.25V, source impedance R = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (R = 200Ω),
CC
S
IN
signal AC-coupled to IN_, INB_ is AC grounded, V
is the differential output between OUT_+ and OUT_-, f
= 5MHz, R = 200Ω
IN_ L
OUT
between the differential outputs, C = 20pF from each output to ground, T = 0°C to +70°C, unless otherwise specified.)
L
A
SMALL-SIGNAL BANDWIDTH
vs. FREQUENCY
SMALL-SIGNAL BANDWIDTH
vs. FREQUENCY
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
25
20
15
10
5
25
20
15
10
5
25
20
15
10
5
V
= 112mV
,
V
R
= 112mV
V
IN
= 500mV
,
IN_
P-P
IN
P-P
IN_
P-P
R
IN
= 200Ω
= 50Ω
R = 200Ω
IN
0
0
0
-5
-5
-5
0.1
1
10
FREQUENCY (MHz)
100
1000
0.1
1
10
FREQUENCY (MHz)
100
1000
0.1
1
10
FREQUENCY (MHz)
100
1000
COMPLEX INPUT IMPEDANCE MAGNITUDE
vs. FREQUENCY
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
COMPLEX INPUT IMPEDANCE MAGNITUDE
vs. FREQUENCY
140
130
120
110
100
90
25
20
15
10
5
70
D2/D1/D0 = 0/0/1
D2/D1/D0 = 0/0/0
IN
V
= 500mV
= 50Ω
IN
P-P
R
IN
= 100Ω
R
= 50Ω
R
IN
65
60
55
50
45
40
35
30
80
0
70
60
-5
0
5
10
15
20
25
30
0.1
1
10
FREQUENCY (MHz)
100
1000
0
10
20
30
40
50
FREQUENCY (MHz)
FREQUENCY (MHz)
COMPLEX INPUT IMPEDANCE MAGNITUDE
vs. FREQUENCY
COMPLEX INPUT IMPEDANCE MAGNITUDE
vs. FREQUENCY
HARMONIC DISTORTION
vs. FREQUENCY
1150
275
250
225
200
175
150
125
100
D2/D1/D0 = 0/1/1
-20
-30
-40
-50
-60
-70
-80
V
R
L
= 1V DIFFERENTIAL
P-P
= 200Ω
D2/D1/D0 = 0/1/0
OUT
R
IN
= 1kΩ
1000
850
700
550
400
250
100
R
IN
= 200Ω
THIRD HARMONIC
SECOND HARMONIC
0
4
8
12
16
20
0
4
8
12
16
20
0
5
10
15
20
25
30
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (MHz)
4
_______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
Typical Operating Characteristics (continued)
(MAX2034 Typical Application Circuit, V = +4.75V to +5.25V, source impedance R = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (R = 200Ω),
CC
S
IN
signal AC-coupled to IN_, INB_ is AC grounded, V
is the differential output between OUT_+ and OUT_-, f
= 5MHz, R = 200Ω
IN_ L
OUT
between the differential outputs, C = 20pF from each output to ground, T = 0°C to +70°C, unless otherwise specified.)
L
A
TWO-TONE ULTRASOUND-SPECIFIC IMD3
vs. FREQUENCY
LARGE-SIGNAL NOISE FIGURE
vs. OFFSET FREQUENCY
0
-10
-20
-30
-40
-50
-60
-70
6
5
4
3
2
1
0
V
R
L
= 1V DIFFERENTIAL
P-P
OUT
= 200Ω
R
= 200Ω
= 200Ω
= 5MHz
IN
R
L
IN_
f
V
= 300mV
P-P
IN
V
= 200mV
P-P
IN
V
IN
= 112mV
P-P
SMALL-SIGNAL
NOISE FIGURE
0
5
10
15
20
25
30
0.1
1
10
100
FREQUENCY (MHz)
OFFSET FREQUENCY (kHz)
CHANNEL-TO-CHANNEL CROSSTALK
vs. FREQUENCY
GAIN-ERROR HISTOGRAM
SAMPLE SIZE = 243 UNITS
-30
50
45
40
35
30
25
20
15
10
5
V
= 1V DIFFERENTIAL
P-P
OUT
R = 200Ω
L
f
= 5MHz, V = 112mV
IN_
IN
P-P
-40
-50
-60
-70
-80
ADJACENT CHANNELS
-90
-100
0
1
10
100
FREQUENCY (MHz)
GAIN ERROR (dB)
SUPPLY CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
LARGE-SIGNAL RECOVERY
MAX2034 toc15
130
110
90
ALL CHANNELS ACTIVE
f
= 5MHz
IN_
INPUT IN_
500mV/div
R
= 200Ω
L
DIFFERENTIAL
OUTPUT
70
OUT_+ - OUT_-
2.0V/div
NO LOAD
50
30
0
1
2
3
4
400ns/div
DIFFERENTIAL OUTPUT VOLTAGE (V
)
P-P
_______________________________________________________________________________________
5
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
Typical Operating Characteristics (continued)
(MAX2034 Typical Application Circuit, V = +4.75V to +5.25V, source impedance R = 200Ω, PD = 0, D2/D1/D0 = 0/1/0 (R = 200Ω),
CC
S
IN
signal AC-coupled to IN_, INB_ is AC grounded, V
is the differential output between OUT_+ and OUT_-, f
= 5MHz, R = 200Ω
IN_ L
OUT
between the differential outputs, C = 20pF from each output to ground, T = 0°C to +70°C, unless otherwise specified.)
L
A
CLAMP SYMMETRY UNDER
TRANSMIT RECOVERY
LARGE-SIGNAL RECOVERY
MAX2034 toc17
MAX2034 toc16
f
= 5MHz
IN_
f
= 10MHz
IN_
SINGLE-ENDED
OUTPUT OUT_+
1V/div
INPUT IN_
500mV/div
DIFFERENTIAL
OUTPUT
OUT_+ - OUT_-
2.0V/div
SINGLE-ENDED
OUTPUT OUT_-
1V/div
200ns/div
400ns/div
Pin Description
PIN
1
NAME
INC1
INB1
ZF2
FUNCTION
Channel 1 Analog Input Clamp. Input port to the integrated clamping diodes.
2
Channel 1 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin.
Channel 2 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor.
3
Channel 2 LNA Analog Input. Single-ended input for channel 2 amplifier. Connect the analog input to
the source circuit through a series capacitor.
4
IN2
5
6
7
INC2
INB2
ZF3
Channel 2 Analog Input Clamp. Input port to the integrated clamping diodes.
Channel 2 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin.
Channel 3 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor.
Channel 3 LNA Analog Input. Single-ended input for channel 3 amplifier. Connect the analog input to
the source circuit through a series capacitor.
8
IN3
9
INC3
INB3
ZF4
Channel 3 Analog Input Clamp. Input port to the integrated clamping diodes.
10
11
Channel 3 Analog Bypass Input. Connect a capacitor to GND as close as possible to the pin.
Channel 4 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor.
Channel 4 LNA Analog Input. Single-ended input for channel 4 amplifier. Connect the analog input to
the source circuit through a series capacitor.
12
IN4
13
14
INC4
INB4
Channel 4 Analog Input Clamp. Input port to the integrated clamping diodes.
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
5V Power Supply. Supply for the four LNAs. Bypass each V
close as possible to the pin.
supply with a 100nF capacitor as
CC
V
CC
6
_______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
Pin Description (continued)
PIN
NAME
FUNCTION
Digitally Programmable Inputs. Programs the input impedance of each amplifier. See Table 1 on
input impedance programming information.
18, 19, 42
D1, D0, D2
23
24
28
29
31
32
35
36
43
47
OUT4-
OUT4+
OUT3-
OUT3+
OUT2-
OUT2+
OUT1-
OUT1+
PD
Channel 4 LNA Analog Inverting Output
Channel 4 LNA Analog Noninverting Output
Channel 3 LNA Analog Inverting Output
Channel 3 LNA Analog Noninverting Output
Channel 2 LNA Analog Inverting Output
Channel 2 LNA Analog Noninverting Output
Channel 1 LNA Analog Inverting Output
Channel 1 LNA Analog Noninverting Output
Power-Down. Drive PD high to put the device in sleep mode. Drive PD low for normal mode.
Channel 1 Active Impedance-Matching Port. AC-couple to the source circuit with a capacitor.
ZF1
Channel 1 LNA Analog Input. Single-ended input for channel 1 amplifier. Connect the analog input to
the source circuit through a series capacitor.
48
EP
IN1
GND
Exposed Paddle. Solder the exposed paddle to the ground plane using multiple vias.
amplifier, A, being defined with a differential output. For
Detailed Description
common input impedances, the internal digitally pro-
grammed 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 MAX2034 is a four-channel, ultra-low-noise pream-
plifier. Each amplifier features single-ended inputs, dif-
ferential outputs, and provides an accurate fixed gain of
19dB with 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 device has an exceptionally low noise figure, making
it ideal for use in ultrasound front-end designs. Noise fig-
ure is typically 2.2dB for a source impedance and pro-
grammed input impedance of 200Ω.
The gain and input impedance of the MAX2034 vs. fre-
quency are shown in the Typical Operating Char-
acteristics. 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.
The MAX2034 is optimized for excellent dynamic range
and linearity performance characteristics, making it ideal
for ultrasound-imaging modalities including second har-
monic 2D imaging and continuous wave Doppler. The
Table 1. Digitally Programmable Input
Impedance
device achieves an HD2 of -68dBc at V
= 1V
and
OUT
P-P
f
= 5MHz, and an ultrasound-specific two-tone IMD3
IN_
performance of -55dBc at V
= 1V
and f
=
IN_
OUT
P-P
D2
0
D1
0
D0
0
R
(Ω)
IN
5MHz. See the Ultrasound-Specific IMD3 Specification in
the Applications Information section.
50
0
0
1
100
200
1k
Active Impedance Matching
To provide exceptional noise-figure characteristics, the
input impedance of each amplifier uses a feedback
topology for active impedance matching. A feedback
0
1
0
0
1
1
1
0
0
resistor of the value (1 + (A / 2)) x R is added between
S
1
0
1
the inverting output of the amplifier to the input. The
Defined by external resistor
1
1
0
input impedance is the feedback resistor, Z , divided
F
by 1 + (A / 2). The factor of two is due to the gain of the
1
1
1
_______________________________________________________________________________________
7
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
Digitally Programmable Input Impedance
Functional Diagram
The MAX2034 features an on-chip digitally programma-
ble input impedance, which makes the part compatible
D2/D1/D0
with a variety of source impedances ranging from 50Ω
to 1kΩ. The input impedance can be programmed for
PD
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
ZF1
impedance can be supported by using an off-chip
external feedback resistor, R . To utilize this feature, set
F
D2, D1, and D0 to any of the four external resistor-con-
trolled states shown in Table 1. The value of the off-chip
feedback resistor can be determined by using the fol-
lowing relationship:
IN1
OUT1-
OUT1+
INC1
R = (1 + (A / 2)) x R
F
S
MAX2034
INB1
where R is the source impedance, and A is the gain of
S
the amplifier (A = 9) defined with a differential output.
Noise Figure
The MAX2034 is designed to provide maximum input
sensitivity with its exceptionally low noise figure. The
input active devices are selected for very low equiva-
lent 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
ZF2
IN2
OUT2-
OUT2+
INC2
INB2
is approximately 2.2dB for R = R = 200Ω. Table 2
IN
S
illustrates the noise figure for other input impedances.
Table 2. Noise Figure vs. Source and
Input Impedances
ZF3
Rs (Ω)
50
R
(Ω)
NF (dB)
4.1
IN
50
IN3
OUT3-
OUT3+
INC3
100
100
200
2.9
200
2.2
1000
1000
1.4
INB3
Input Clamp
The MAX2034 includes configurable integrated input-
clamping 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 pre-
ferred, simply leave INC1–INC4 unconnected.
ZF4
IN4
OUT4-
OUT4+
INC4
INB4
8
_______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
The Typical Application Circuit illustrates these cou-
pling 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 tran-
sient overloads associated with transmitter operation in
ultrasound applications.
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 capaci-
tor 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.
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 differen-
tial outputs if the next stage has a different common-
mode input range.
Overload Recovery
The device is also optimized for quick overload recov-
ery for operation under the large input signal conditions
that are typically found in ultrasound input-buffer imag-
ing applications. Internal signal clipping is symmetrical.
Input overloads can be prevented with the input-clamp-
ing diodes. See the Typical Operating Characteristics
that illustrate the rapid recovery time from a transmit-
related overload.
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.
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 pow-
ered 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 exposed paddle (EP) of the MAX2034’s thin QFN-
EP 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 low-
inductance 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 con-
necting 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 single-
ended inputs at IN1–IN4.
-25dB
ULTRASOUND IMD3
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 high-
pass 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.
F1 - (F2 - F1)
F1
F2
F2 + (F2 - F1)
Figure 1. Ultrasound IMD3 Measurement Technique
_______________________________________________________________________________________
9
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
D2/D1/D0
PD
+V
ZF_
18nF
100nF
100nF
100nF
IN_
OUT_-
OUT_+
INC_
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 ultrasound-
specific IMD3 two-tone specification. In this measure-
ment, 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 sig-
nal in ultrasound applications. See Figure 1.
10 ______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
Typical 200Ω Application Circuit
+5V
100nF
100nF
18nF
100nF
47 46 45 44 43 42 41 40 39
37
48
38
INC1
100nF
100nF
OUT1+
OUT1-
36
35
34
33
32
31
30
29
28
27
26
25
1
2
R
= 200Ω
S
INB1
ZF2
V
CC
100nF
100nF
3
GND
IN2
18nF
100nF
100nF
4
100nF
OUT2+
OUT2-
100nF
100nF
INC2
INB2
ZF3
5
R
= 200Ω
S
6
V
CC
MAX2034
7
IN3
18nF
100nF
100nF
OUT3+
OUT3-
8
100nF
INC3
9
EXPOSED PADDLE
R
= 200Ω
S
V
CC
INB3
ZF4
IN4
10
11
12
GND
GND
100nF
100nF
18nF
100nF
14 15 16 17 18 19 20 21 22
24
13
23
R
= 200Ω
S
100nF
100nF
100nF
100nF
100nF
+5V
+5V
______________________________________________________________________________________ 11
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
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
(NE-1) X
e
E/2
k
e
D/2
C
(ND-1) X
e
D2
D
L
D2/2
b
L
E2/2
C
L
k
DETAIL B
E2
e
C
C
L
L
L
L1
L
L
e
e
A
A1
A2
PACKAGE OUTLINE
32, 44, 48, 56L THIN QFN, 7x7x0.8mm
1
21-0144
E
2
12 ______________________________________________________________________________________
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
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.)
PACKAGE OUTLINE
32, 44, 48, 56L THIN QFN, 7x7x0.8mm
2
21-0144
E
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
is a registered trademark of Maxim Integrated Products, Inc.
Springer
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