MAX3509EUP+T [MAXIM]
Narrow Band Medium Power Amplifier, 5MHz Min, 65MHz Max, 1 Func, TSSOP-20;
| 型号： | MAX3509EUP+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Narrow Band Medium Power Amplifier, 5MHz Min, 65MHz Max, 1 Func, TSSOP-20 放大器 有线电视 |
| 文件： | 总10页 (文件大小：213K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1700; Rev 1; 6/05
Upstream CATV Amplifier
General Description
Features
The MAX3509 is a programmable power amplifier for
use in CATV upstream applications. The device outputs
up to 66dBmV QPSK through a 1:1 transformer. It fea-
tures variable gain controlled by a 3-wire digital serial
bus. Gain control is available in 1dB steps. The device
operates over a 5MHz to 65MHz frequency range.
ꢀ Ultra-Low Power-Up/Down Transients,
25mV (typ) at 66dBmV Output
ꢀ Single-Supply Operation
ꢀ Output Level Ranges from <12dBmV to 67dBmV
(QPSK)
The MAX3509 offers a transmit-disable mode, which
places the device in a high-isolation state for use
between bursts in TDMA systems. In this mode, all ana-
log functions are shut down, minimizing output noise
and power consumption. When entering and leaving
transmit-disable mode, transients are kept to 25mV
nominal at full gain. In addition, supply current is re-
duced to 7.8mA.
ꢀ Gain Programmable in 1dB Steps
ꢀ Low Transmit Output Noise Floor: -41dBmV
(160kHz BW)
ꢀ Low Transmit-Disable Output Noise: -70dBmV
ꢀ Shutdown Mode
An additional power-down mode is available. Shutdown
mode disables all circuitry and reduces current con-
sumption to less than 1µA.
Ordering Information
The MAX3509 is available in a 20-pin TSSOP-EP pack-
age for the extended-industrial temperature range
(-40°C to +85°C).
PIN-
PACKAGE
PART
TEMP RANGE
MAX3509EUP
-40°C to +85°C
-40°C to +85°C
20 TSSOP-EP*
20 TSSOP-EP*
Applications
CATV Status Monitors
MAX3509EUP+
Telephony-Over-Cable
*EP = Exposed paddle.
+Denotes lead-free package.
OPENCATV Set-Top Boxes CATV Infrastructures
Cable Modems
Typical Operating Circuit
Pin Configuration
TOP VIEW
3
4
17
V
+9V
0.1 F
CC2
+9V
0.1 F
V
CC1
TXEN
1
2
3
4
5
6
7
8
9
20 SCLK
19 SDA
18 CS
GND1
SHDN
MAX3509
4700pF
16
V
CC1
1000pF
1000pF
OUT
5
6
OUT+
OUT-
IN+
IN-
GND1
IN+
17 V
CC2
T1
1:1
IN
4700pF
MAX3509
16 OUT+
15 OUT-
15
IN-
14
GND1
14
V
V
+9V
0.1 F
CC2
CC2
8
7
V
+9V
0.1 F
CC1
V
CC1
13 GND
12 GND
11 GND
GND1
GND
GND2
*
9
2
1
20
19
18
GND 10
GND
GND
GND
GND
GND
SHDN
TXEN
SCLK
SDA
CS
10
11
12
13
EXPOSED PADDLE
LOGIC
INPUTS
TSSOP-EP
*EXPOSED PADDLE
†
Covered by U.S. Patent numbers 5,748,027 and 5,994,955.
________________________________________________________________ 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.
Upstream CATV Amplifier
ABSOLUTE MAXIMUM RATINGS
CC1 CC2
V
, V
to GND, GND1 .................................-0.3V to +10.0V
Continuous Power Dissipation (T = +70°C)
A
SCLK, SDA, CS, TXEN, SHDN to GND
and GND1 .........................................................-0.3V to +5.5V
Continuous Input Voltage (IN+, IN-)....................................2V
Continuous Current (OUT+, OUT-) .....................................80mA
20-Pin TSSOP-EP (derate at 27mW/°C above
+70°C)........................................................................2200mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
P-P
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(V
= V
= 8.5V to 9.5V, TXEN = SHDN = high, D7 = 1, T = -40°C to +85°C, unless otherwise noted. No input signal applied.
CC2 A
CC1
Typical parameters are at T = +25°C.) (Note 2.)
A
PARAMETER
Supply Voltage
SYMBOL
CONDITIONS
MIN
TYP
MAX
9.5
UNITS
V
V
8.5
CC
CC
Supply Current Transmit Mode
I
I
I
84
7.8
10
115
mA
Supply Current Transmit-Disable
Mode
TXEN = low or D7 = 0
SHDN = low, TXEN = low
10
mA
CC
Supply Current Shutdown Mode
Input High Voltage
µA
V
CC
V
2.0
INH
Input Low Voltage
V
0.8
V
INL
Input High Current
I
100
µA
µA
BIASH
Input Low Current
I
-100
BIASL
AC ELECTRICAL CHARACTERISTICS
(MAX3509 EV kit, V
= V
= 8.5V to 9.5V, TXEN = SHDN = high, D7 = 1, V
= 34dBmV differential, output impedance =
INPUT
CC1
CC2
75 through a 1:1 transformer, T = -40°C to +85°C, unless otherwise noted. Typical parameters are at T = +25°C.) (Note 2.)
A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
T
= +25 C, f
= 42MHz, gain-control
INPUT
INPUT
INPUT
A
33
word = 63
T
A
= +25 C, f
= 42MHz, gain-control
= 42MHz, gain-control
-22
word = 0
Voltage Gain
A
dB
V
T
A
= +25 C, f
22.8
24.2
26.7
31
word = 50
f
f
= 42MHz, gain-control word = 63
= 42MHz, gain-control word = 0
= 42MHz, gain-control word = 50
INPUT
INPUT
-21
f
21.3
24.2
0.1
26.7
0.4
INPUT
V
V
= 60dBmV, f
= 60dBmV, f
= 5MHz to 42MHz
= 5MHz to 65MHz
dB
OUTPUT
OUTPUT
INPUT
INPUT
Gain Fariness (note 1)
Gain Step Size
0.3
0.9
f
= 5MHz to 65MHz, A = -20dB to
V
+33dB
INPUT
0.7
1
1.3
dB
2
_______________________________________________________________________________________
Upstream CATV Amplifier
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX3509 EV kit, V
= V
= 8.5V to 9.5V, TXEN = SHDN = high, D7 = 1, V
= 34dBmV differential, output impedance =
CC1
CC2
INPUT
75 through a 1:1 transformer, T = -40°C to +85°C, unless otherwise noted. Typical parameters are at T = +25°C.) (Note 2.)
A
A
PARAMETER
SYMBOL
CONDITIONS
BW = 160kHz, A = 32dB
MIN
TYP
MAX
-85
UNITS
dBc
V
Transmit Mode Noise (Note 1)
BW = 160kHz, A = -20dB, T = +25 C
-41
-39.5
-38.5
V
A
dBmV
dBmV
BW = 160kHz, A = -20dB, T = +85 C
V
A
Transmit-Disable Mode Noise
Floor
TXEN = low, BW = 160kHz, A = +32dB,
V
-70
f
= 5MHz to 65MHz (Note 1)
INPUT
TXEN Enable Transient Duration
TXEN Disable Transient Duration
TXEN rise time <0.1µs, T = +25°C (Note 1)
1.4
1
2
1.5
100
9
µs
µs
A
TXEN fall time <0.1µs, T = +25°C (Note 1)
A
A
A
= 32dB, T = +25°C
25
1.5
A
TXEN Transient Step Size
(Note 1)
V
V
mV
P-P
= 2dB or lower, T = +25°C
A
f
T
= 5MHz to 65MHz, single-ended,
= +25°C (Note 1)
INPUT
A
Input Impedance
Z
1.2
1.2
170
-53
k
INPUT
Output Impedance in Transmit
Mode
Z
f
= 5MHz to 65MHz, T = +25°C (Note 1)
INPUT A
OUTPUT
Output Impedance in
Transmit-Disable Mode
TXEN = low, f
T
= 5MHz to 65MHz,
INPUT
Z
OUTPUT
IM3
= +25°C (Note 1)
A
Input tones at 65MHz and 65.2MHz,
V
Two-Tone Third-Order Distortion
dBc
= 31dBmV/tone, A = 32dB (Note 1)
INPUT
INPUT
INPUT
V
V
V
= +60dBmV
= +66dBmV
-56
-56
-53
-50
OUTPUT
f
f
= 33MHz
= 65MHz
OUTPUT
2nd Harmonic Distortion
HD2
HD3
dBc
dBc
V
= 66dBmV
-56
-50
OUTPUT
(Note 1)
V
V
= +60dBmV
= +66dBmV
-56
-53
-53
OUTPUT
f
f
= 22MHz
= 65MHz
INPUT
INPUT
-48.5
OUTPUT
3rd Harmonic Distortion
V
= 66dBmV
-43
26
-40
OUTPUT
(Note 1)
Output 1dB Compression Point
AM to AM
P1dB
A
= 32dB, 65MHz (Note 1)
dBm
dB
V
A
= 32dB, V
swept from 34dBmV to
INPUT
V
AM/AM
0.1
1.7
38dBmV (Note 1)
A
= 32dB, V
swept from 34dBmV to
INPUT
V
AM to PM
AM/PM
degrees
38dBmV (Note 1)
_______________________________________________________________________________________
3
Upstream CATV Amplifier
TIMING CHARACTERISTICS
(V
= V
8.5V to 9.5V, TXEN = SHDN = high, D7 = 1, T = +25°C, unless otherwise noted.) (Note 1.)
CC2 = A
CC1
PARAMETER
SYMBOL
COMMENT
MIN
10
20
10
20
50
50
50
50
TYP
MAX
UNITS
ns
t
CS to SCK Rise Setup Time
CS to SCK Rise Hold Time
SDA to SCK Setup Time
SDA to SCK Hold Time
SDA Pulse-Width High
SDA Pulse-Width Low
SCK Pulse-Width High
SCK Pulse-Width Low
SENS
t
ns
SENH
t
ns
SDAS
SDAH
t
ns
t
ns
DATAH
t
ns
DATAL
t
ns
SCKH
t
ns
SCKL
Note 1: Guaranteed by design and characterization.
Note 2: Tested parameters specified from -40°C to +85°C are guaranteed by design and characterization to 3 sigma for
temperatures less than 25°C.
Typical Operating Characteristics
(MAX3509 EV kit, V
= V
= +9V, V = +34dBmV, TXEN = SHDN = high, D7 = 1, f
= 10MHz, Z
= 75 through a 1:1
CC1
CC2
IN
INPUT
LOAD
transformer, T = +25°C, unless otherwise noted.)
A
SUPPLY CURRENT
vs. OUTPUT POWER
SUPPLY CURRENT vs. TEMPERATURE
SUPPLY CURRENT vs. TEMPERATURE
TRANSMIT DISABLE
TRANSMIT ENABLE
100
140
9.0
8.5
8.0
7.5
7.0
6.5
6.0
95
90
85
80
75
70
65
60
130
120
110
100
90
T
= +85 C
A
T
= +25 C
A
T
= -40 C
A
80
70
-40
-15
10
35
60
85
-40
-15
10
35
60
85
30
36
42
48
54
60
66
72
TEMPERATURE ( C)
TEMPERATURE ( C)
OUTPUT POWER (dBmV)
VOLTAGE GAIN vs. TEMPERATURE
(CONTROL WORD = 25)
VOLTAGE GAIN vs. SUPPLY VOLTAGE
(CONTROL WORD = 25)
VOLTAGE GAIN vs. SUPPLY VOLTAGE
(CONTROL WORD = 50)
0.5
0.4
0.32
0.30
0.28
0.26
0.24
0.22
0.20
25.2
25.0
24.8
24.6
24.4
24.2
24.0
8.5V
T
= +85 C
A
T
= +85 C
A
0.3
0.2
0.1
9.5V
9.0V
0
T
T
= -40 C
= +25 C
A
A
-0.1
-0.2
-0.3
-0.4
-0.5
T
T
= +25 C
= -40 C
A
A
-40
-15
10
35
60
85
8.5 8.6 8.7 8.8 8.9 9.0 9.1 9.2 9.3 9.4 9.5
SUPPLY VOLTAGE (V)
8.5 8.6 8.7 8.8 8.9 9.0 9.1 9.2 9.3 9.4 9.5
SUPPLY VOLTAGE (V)
TEMPERATURE ( C)
4
_______________________________________________________________________________________
Upstream CATV Amplifier
Typical Operating Characteristics (continued)
(MAX3509 EV kit, V
= V
= +9V, V = +34dBmV, TXEN = SHDN = high, D7 = 1, f
= 10MHz, Z
= 75 through a 1:1
CC1
CC2
IN
INPUT
LOAD
transformer, T = +25°C, unless otherwise noted.)
A
GAIN STEP
vs. CONTROL WORD
VOLTAGE GAIN
vs. CONTROL WORD
VOLTAGE GAIN vs. FREQUENCY
50
40
30
1.3
A
B
40
30
20
10
1.2
1.1
1.0
0.9
0.8
0.7
10MHz
C
D
E
20
10
0
60MHz
0
-10
F
G
-20
-30
-10
-20
-30
GAIN-CONTROL WORD
A = 63, B = 57, C = 48,
D = 36, E = 24, F = 12,
G = 6
-40
-50
0
10
20
30
40
50
60
0
10
20
30
40
50
60
5
10
100
500
CONTROL WORD (DECIMAL)
CONTROL WORD (DECIMAL)
FREQUENCY (MHz)
2ND HARMONIC DISTORTION
vs. INPUT FREQUENCY
POWER-UP/DOWN TRANSIENTS
vs. CONTROL WORD
TRANSMIT OUTPUT NOISE vs. GAIN
-20
-58
-62
-66
-70
-74
100
-22
-24
-26
-28
-30
-32
-34
-36
-38
-40
-42
66dBmV
60dBmV
10
1
0
10
20
30
40
50
60
70
-24
-14
-4
6
16
26
36
0
30
CONTROL WORD
10
20
60
40
50
70
GAIN (dB)
FREQUENCY (MHz)
2ND HARMONIC DISTORTION
vs. INPUT FREQUENCY
3RD HARMONIC DISTORTION vs.
INPUT FREQUENCY AND OUTPUT POWER
QPSK OUTPUT SPECTRUM
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-50
-55
-60
-65
-70
-75
-80
-40
-45
-50
-55
-60
-65
-70
-75
-80
-85
-90
V
= 66dBmV
OUT
66dBmV
60dBmV
1280ksps
0.25
10dBmV
30dBmV
30dBmV
10dBmV
SPAN 5MHz
CENTER 22MHz
500kHz/div
0
10
20
30
40
50
60
70
0
10
20
30
40
50
60
70
FREQUENCY (MHz)
FREQUENCY (MHz)
____________________________________________________________________________________
5
Upstream CATV Amplifier
Typical Operating Characteristics (continued)
(MAX3509 EV kit, V
= V
= +9V, V = +34dBmV, TXEN = SHDN = high, D7 = 1, f
= 10MHz, Z
= 75 through a 1:1
CC1
CC2
IN
INPUT
LOAD
transformer, T = +25°C, unless otherwise noted.)
A
OUTPUT SPECTRUM
QPSK OUTPUT SPECTRUM
-30
-40
-20
V
= 66dBmV
V
= 66dBmV
OUT
OUT
-30
-40
1280ksps
160ksps
0.25
0.25
-50
-60
-50
-70
-60
-80
-70
-90
-80
-100
-110
-120
-130
-90
-100
-110
-120
STOP 70MHz
START 15MHz
SPAN 1MHz
CENTER 22MHz
5.5MHz/div
100kHz/div
Pin Description
PIN
1
NAME
TXEN
SHDN
FUNCTION
Transmit Enable. To disable the MAX3509 and provide high input/output isolation, drive TXEN low. Drive
TXEN high for normal operation.
2
Shutdown. To enable low-power shutdown, drive SHDN low. Drive SHDN high for normal operation.
Programmable-Gain Amplifier (PGA) +9V Supply. Bypass to GND1 with a 0.1µF decoupling capacitor as
close to the part as possible.
3, 8
4, 7
5
V
CC1
GND1
IN+
PGA Ground. Connect to ground with a low inductance path.
Noninverting PGA Input. Along with IN-, this port forms a high-impedance differential input to the PGA.
Driving this port differentially increases the rejection of second-order distortion at low output levels.
6
IN-
Inverted PGA Input. When not used, AC-coupled to ground. See IN+.
Ground
9–13
GND
Power Amplifier Bias +9V Supply. Bypass to GND2 (exposed paddle) with a 0.1µF decoupling capacitor as
close to the part as possible.
14,17
V
CC2
15
16
18
19
20
OUT-
OUT+
CS
Inverted Output. AC-couple to output transformer. Used in conjunction with OUT+.
Noninverted Output. See OUT-.
Serial-Interface Enable. TTL-compatible input. See the Serial Interface section.
Serial-Interface Data. TTL-compatible input. See the Serial Interface section.
Serial-Interface Clock. TTL-compatible input. See the Serial Interface section.
SDA
SCLK
Exposed
Paddle
Power Amplifier Bias Ground. Connect to ground with a low inductance path. Ensure a low thermal resistive
path to PC board. See Layout Issues.
GND2
6
_______________________________________________________________________________________
Upstream CATV Amplifier
SHDN
TXEN
PA BIAS
V
CC1
V
CC2
PGA BIAS
OUT+
OUT-
IN+
IN-
DAC
MAX3509
SERIAL DATA INTERFACE
CS SDA SCLK
Figure 1. MAX3509 Functional Diagram
convert to a single-ended output. In transmit-disable
mode, bias to the power amplifier is reduced to a mini-
mal level, which provides high input to output isolation
and low output noise.
Detailed Description
The following sections describe the blocks shown in the
functional diagram (Figure 1).
Programmable-Gain Amplifier
The PGA consists of the variable-gain amplifier (VGA)
and the digital-to-analog converter (DAC), which pro-
vide better than 55dB of output level control in 1dB
steps.
Serial Interface
The serial interface has an active-low enable (CS) to
bracket the data, with data clocked in MSB first on the
rising edge of SCLK. Data is stored in the storage latch
on the rising edge of CS. The serial interface controls the
state of the PGA. Tables 1 and 2 show the register for-
mat. Serial-interface timing is shown in Figure 2.
The PGA is implemented as a programmable Gilbert-
cell attenuator. It uses a differential architecture to
achieve maximum linearity. The gain of the PGA is
determined by a 6-bit word (D5–D0) programmed
through the serial data interface (Tables 1 and 2).
PGA Bias Cell
The bias cell in the MAX3509 is controlled by the logic
levels present at TXEN and SHDN, as well as the pro-
gram state of D7, the MSB of the 8-bit program word.
Transmit-disable mode is actuated when the TXEN pin
is driven to a logic low or when D7 = 0. In this mode,
current to the PGA and power amps is reduced signifi-
cantly while maintaining normal current flow to the seri-
al data interface and DAC. This preserves the program
stored in the serial data interface.
Specified performance is achieved when the input is
driven differentially. The device may be driven single
ended; however, a slight increase in even-order distor-
tion may result at low output levels. To drive the device
in this manner, one of the input pins must be capaci-
tively coupled to ground. Use a capacitor value large
enough to allow for a low-impedance path to ground at
the lowest frequency of operation.
A logic low at the SHDN pin overrides the state of the
TXEN pin or D7. In shutdown mode, the current to the
PGA, power amp, serial data interface, and DAC is cut
off, allowing only leakage currents to flow. The stored
gain control program is lost in this mode.
Power Amplifier
The power amplifier has two current-feedback ampli-
fiers in an instrumentation amplifier configuration. This
architecture provides superior even-order distortion
performance but requires an external transformer to
_______________________________________________________________________________________
7
Upstream CATV Amplifier
Power Amp Bias Cell
The power amp bias cell is used to enable and disable
bias to the output power amplifier. This is controlled by
TXEN and SHDN.
C
G
B
A
D
E
F
Functional Modes
The MAX3509 has three functional modes controlled
through the serial interface or external pins (Table 2):
transmit mode, transmit-disable mode, and shutdown.
Transmit Mode
Transmit mode is the normal active mode of the
MAX3509. Drive TXEN and SHDN high, and set D7 = 1
to activate transmit mode.
D7
D6
D5
D4
D3
D2
D1
D0
E. t
F. t
G. t
A. t
SCKH
SENS
SDAS
SDAH
SCKL
B. t
C. t
D. t
SENH
/t
DATAH DATAL
Transmit-Disable Mode
When in transmit-disable mode, all analog circuitry is
shut down. This mode is activated by driving TXEN low
or setting D7 = 1 while keeping SHDN high. This mode
is typically used between bursts in TDMA systems.
Transients are controlled by the transformer balance.
Figure 2. Serial-Interface Timing Diagram
Table 1. Serial-Interface Control Word
BIT
MNEMONIC
DESCRIPTION
Shutdown Mode
In normal operation, the shutdown pin (SHDN) is held
high. When SHDN is driven low, all circuits within the IC
are disabled. Only leakage currents flow in this mode.
Data stored within the serial-data interface latches will
be lost upon entering this mode. Current draw is
reduced to 1µA (typ) in shutdown mode.
MSB 7
D7
D6
D5
D4
D3
D2
D1
D0
Transmit Disable
6
Not used
5
Gain Control, Bit 5
Gain Control, Bit 4
Gain Control, Bit 3
Gain Control, Bit 2
Gain Control, Bit 1
Gain Control, Bit 0
4
3
2
1
LSB 0
Table 2. Truth Table
GAIN CONTROL
WORD
TXEN
D7
D6
D5
D4
D3
D2
D1
D0
STATE
SHDN
0
1
1
1
1
1
1
1
1
1
1
X
0
X
1
1
1
1
1
1
1
1
X
X
0
1
1
1
1
1
1
1
1
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Shutdown Mode
Transmit-Disable Mode
Transmit-Disable Mode
Transmit Mode
Gain = -25dB*
Gain = -24dB*
—
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0
0
0
0
0
0
0
0
0
0
0
0
1
1
—
0
—
1
—
1
—
0
—
0
—
1
—
25
—
62
63
Gain = 0dB*
—
1
—
1
—
1
—
1
—
1
—
0
—
Gain = 35dB*
Gain = 36dB*
1
1
1
1
1
1
*Typical gain at +25°C and V = +9V.
CC
8
_______________________________________________________________________________________
Upstream CATV Amplifier
It is recommended that the EP be soldered to a ground
plane on the PC board, either directly or through an
array of plated via holes.
Applications Information
Transformer
To maintain rated performance into a 75 load, a 1:1
impedance ratio output transformer with adequate
bandwidth is required. A step-up transformer with a
1:1.5 impedance ratio will increase gain and output
voltage swing nominally by 1.7dB, but output noise per-
formance will increase by the same amount.
Output Circuit Layout
The differential implementation of the MAX3509’s out-
put has the benefit of reducing even-order distortion,
the most significant of which is second-harmonic distor-
tion. The degree of distortion cancellation depends on
the amplitude and phase balance of the overall circuit.
It is important that the traces that lead from the output
pins be the same length.
Input Circuit
To achieve rated performance, the input of the
MAX3509 must be driven differentially with 34dBmV or
lower input level. The MAX3509 can be driven from a
single-ended source. A slight degradation in even-
order distortion at a 10W output level will result. The dif-
ferential input impedance is approximately 1.2k .
Power-Supply Layout
To achieve minimal coupling between different sections
of the IC, the ideal power-supply layout is a star config-
uration. This configuration has a large-value decoupling
capacitor at the central power-supply node. The power-
supply traces branch out from this node, each going to
a separate power-supply node in the MAX3509 circuit.
At the end of each of these traces is a decoupling
capacitor that provides a very low impedance at the
frequency of interest. This arrangement provides local
power-supply decoupling at each power-supply pin.
Most applications require a differential lowpass filter
preceding the MAX3509. The filter design dictates a
terminating resistance of a specified value. Place this
resistance across the AC-coupled inputs (see Typical
Operating Circuit).
The MAX3509 has sufficient gain to produce an output
level of 66dBmV when driven with a 34dBmV input sig-
nal. Rated performance is achieved with this input
level. When a lower input level is present, the maximum
output level will be reduced proportionally and output
linearity will improve. If an input level greater than
34dBmV is used, distortion performance degrades.
The power-supply traces must be made as thick as
practical to keep resistance well below 1 .
Ground inductance degrades distortion performance.
Therefore, ground plane connections to GND, GND1,
and GND2 should be made with multiple vias if possi-
ble.
If a single-ended source drives the MAX3509, one of the
input terminals must be capacitively coupled to ground
(IN+ or IN-). The value of this capacitor must be large
enough to look like a short circuit at the lowest frequen-
cy of interest. For operation at 5MHz with a 50 source
impedance, a value of 0.1µF will suffice.
IN+
A typical model for the MAX3509 input impedance is
shown in Figure 3.
2.5k
IN-
1.9pF
Layout Issues
A well-designed PC board is an essential part of an RF
circuit. For best performance, pay attention to power-
supply layout issues, as well as the output circuit layout.
Figure 3. Typical Equivalent Input Circuit
Exposed Paddle Thermal Considerations
The exposed paddle (EP) of the MAX3509’s 20-pin
TSSOP-EP package provides a low thermal resistance
path to the die. It is important that the PC board on
which the MAX3509 is mounted be designed to con-
duct heat from this contact. In addition, the EP should
be provided with a low inductance path to electrical
ground.
Chip Information
TRANSISTOR COUNT: 1085
________________________________________________________________________________________
9
Upstream CATV Amplifier
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, TSSOP 4.40mm BODY
1
21-0066
G
1
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.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
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