19-1331; Rev 1; 6/98
MAX3532 Evaluation Kit
General Description
The MAX3532 evaluation kit (EV kit) simplifies evalua-
tion of the MAX3532 CATV upstream driver amplifier. It
includes a serial data interface, which can be pro-
grammed via the parallel port of a standard PC. A
QuickBasic™ program is included to facilitate this func-
tion. This software allows the user to program both the
gain and transmit modes via a simple user interface.
Access to the device input and output is provided
through 50Ω SMA connectors. The input is matched to
50Ω, while the output circuit contains a series 24
Ω
resistor that increases the load on the output trans -
former to 75
Ω
when using 50
Ω
test equipment at the
output.
o
Single +5V Operation
o
Output Level Range from < 8dBmV to 62dBmV
o
Gain Programmable in 1dB Steps via Software
o
350mW Typical Power Dissipation
o
Transmit-Disable Mode
o
Two Shutdown Modes
o
Control Software Included
o
Fully Assembled and Tested Surface-Mount
Board
Features
Evaluates: MAX3532
†
Component List
DESIGNATION QTY
C1–C3, C6
C4, C7
C5
R1
R2, R6–R13,
R16–R20
R3, R4
R5
R14, R15
J1, J4
L1–L4
T1
JU5–JU8
JU1–JU3
J5
None
B1
+5V, GND
U1
None
None
None
4
2
1
1
14
2
1
2
2
4
1
4
3
1
7
1
2
1
1
1
1
DESCRIPTION
0.1µF, 25V min, 10% ceramic capacitors
0.001µF, 25V min, 10% ceramic capacitors
10µF ±10%, 10V min tantalum capacitor
AVX TAJB106K010
51Ω, 5% resistor
Not installed.
8.2Ω 1% resistors
24Ω 5% resistor
100kΩ 5% resistors
SMA connectors (edge mount)
1.2µH inductors
Coilcraft 1008LS-122XKBC
4-to-1 transformer (2:1 voltage ratio)
Mini-Circuits T4-1–2W
3-pin headers (0.1” centers)
2-pin headers (0.1” centers)
Female, right-angle DB25 connector
Shunt
Surface-mount bead core
Panasonic EXC-CL3216U
Test points
MAX3532EAX
MAX3532 data sheet
MAX3532 circuit board
MAX3532 software disk
PART
MAX3532EVKIT
Ordering Information
TEMP. RANGE
-40°C to +85°C
IC PACKAGE
36 SSOP
Component Suppliers
SUPPLIER
AVX
Coilcraft
Mini-Circuits
Panasonic
PHONE
803-946-0690
847-639-6400
718-834-4500
714-373-7939
FAX
803-626-3123
847-639-1469
718-832-4961
714-373-7183
Note:
Please indicate that your are using the MAX3532 when
contacting these suppliers.
_________________________Quick Start
The MAX3532 EV kit is fully assembled and factory
tested. Follow the instructions in the
Connections and
Setup
section.
Note:
The output circuit contains a series 24
Ω
resistor that is
used to bring the load impedance up to 75
Ω.
This must be
accounted for in all measurements (see
Detailed Description).
QuickBasic is a trademark of Microsoft Corp.
†
P7
•
DC supply capable of delivering 5.5V and 200mA of
continuous current.
•
HP or equivalent signal source capable of generat-
ing 40dBmV up to 200MHz.
•
HP8561E or equivalent spectrum analyzer with
approximately 200MHz frequency range.
•
Digital multimeter (DMM) to monitor VCC and ICC, if
desired.
•
Lowpass filters to control harmonic output of signal
sources, if harmonic measurements are desired.
Test Equipment Required
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
MAX3532 Evaluation Kit
MAX3532
†
•
Network analyzer such as HP8753D. (May be used
to measure gain and harmonic levels if configured
with this option; contact manufacturer.)
•
IBM PC or compatible.
•
Male-to-male 25-pin parallel cable, straight through.
1) Connect the +5V power supply to +5V and GND on
the circuit board. Connect a 50
Ω
signal source to
VIN and terminate VOUT with a spectrum analyzer or
network analyzer having a 50
Ω
input impedance. If
using a signal source with a source impedance
other than 50
Ω,
or if a different input impedance is
required, be sure to replace resistor R1 with the
appropriate value.
2) Connect a 25-pin male-to-male cable between the
parallel (printer) port of the PC and the 25-pin female
connector on the EV kit board. Ensure that shunts
are placed on jumpers JU1, JU2, and JU3. These
shunts connect the appropriate pins of the DB25
connector to the serial data interface of the
MAX3532. Also check that pins 1 and 2 of jumpers
JU5 and JU6 are shunted. Additionally, ensure that
pins 2 and 3 of JU7 and JU8 are shunted.
Note:
Pin 1 of all jumpers is defined as the closest pin to
the designator.
•
Place the device in software shutdown
•
Input a new gain state
Test the software by typing the number “6” (then press
Enter) to place the device in software-shutdown mode.
The current being drawn by the device should drop to
approximately 2mA. If this happens, the software is
functioning. If this does not happen, check the appro -
priate connections; in particular, ensure that jumpers
JU1, JU2, and JU3 are shunted.
Valid gain states range from 0 to 63. The nominal
change in gain is 1dB per gain state. The actual gain
range of the MAX3532 is limited at high power levels by
device saturation and is limited at low power levels by
leakage through the device. This leakage is frequency
dependent. See the MAX3532 data sheet for more
detailed information.
Connections and Setup
Gain Adjustment
3) Turn on the power supply. Turn on the PC and the
test equipment. Set the signal source for 36dBmV.
4) From the DOS prompt of the PC, enable QuickBasic
by typing “qbasic”. Open the file “MAX3532.bas”
from the appropriate directory. Run the program.
_______________Detailed Description
When the software is first enabled, it places the
MAX3532 in low-noise mode with a gain state of 58—
approximately 10dB of gain. At this point the device will
draw approximately 75mA. The software allows the
user to do the following:
•
Increment the gain state by 1 (add 1dB of gain)
•
Decrement the gain state by 1 (decrease the gain
by 1dB)
•
Enable high-power mode
•
Enable low-noise mode
•
Place the device in transmit disable mode
Jumpers JU5 and JU6 determine how the shutdown
and transmit-enable features are controlled. Pin 2 of
each of these jumpers is connected directly to the
device. If an external source (such as a modulator chip
or microprocessor) is used to control these features,
simply make the connection to pin 2 of the appropriate
jumper. Otherwise, pins 1 and 2 of JU5 and JU6 must
be shunted.
On-board control of
SHDN
(shutdown) and TXEN
(transmit enable) is accomplished manually via jumpers
JU7 and JU8. JU7 and JU8 are used to place either
+5V or GND at TXEN or
SHDN.
Pin 1 of these jumpers
is GND and pin 3 is +5V.
Shutdown and Transmit Enable
Using the Software
If using another source to drive the serial data interface
of the MAX3532 EV kit (such as a digital pattern gener -
ator or microprocessor), remove the shunts on jumpers
JU1, JU2, and JU3. Access to the serial data interface
is available through pin 1 of these jumpers.
The MAX3532 uses a differential emitter-follower output
to suppress second-order distortion. In order to
achieve a single-ended output and to attain higher out -
put voltages, a 1:2 (voltage ratio) transformer is used.
Furthermore, the output impedance of the MAX3532
itself is less than 2
Ω.
In order to match this output to
75Ω, a pair of 8.2Ω back-termination resistors is used.
Manual Control of
Serial Data Interface
Output Circuit
2
_______________________________________________________________________________________
MAX3532 Evaluation Kit
The output circuit is designed for a good match to 75
Ω,
with the quality of the match largely determined by the
value of the back-termination resistors. In general, in a
75Ω system the large-signal performance of the device
will improve as these resistor values are reduced; how-
ever, the output match will suffer. If a load impedance
other than 75
Ω
is to be used, the value of R3 and R4
can be approximated by the following equation:
R = (R
LOAD
/ 8) - 1
Since most test equipment is supplied with a 50Ω termi-
nation impedance, a series 24
Ω
resistor is provided
with this EV kit to increase the load impedance to a
nominal 75Ω. This places the proper load on the device
but will also reduce the measured output voltage level
by 3.5dB. It is important to consider this when making
any measurements with the EV kit. 3.5dB must be
added to all measurements of voltage gain and output
voltage level (including noise) to arrive at the correct
value for a 75Ω system.
If 75
Ω
test equipment is available, take the following
steps:
1) Remove the 50Ω output SMA connector and replace
it with a 75Ω connector.
2) Remove R5 (the 24
Ω
series output resistor) and
replace it with a 0
Ω
resistor or some other type of
short.
3) Be sure to use a 75Ω cable on the output.
The following is an example of a simple harmonic dis -
tortion measurement. A filter will be needed to reject
the harmonics generated by the signal source. For this
example, a lowpass filter with approximately a 25MHz
to 35MHz cutoff frequency will be required. This filter
will also need to reject at least 20dB of signal at
40MHz. Set the signal source for 20MHz and 36dBmV.
Adjust the amplitude to account for the insertion loss in
the filter. Verify with the spectrum analyzer that the sec -
ond and third harmonics generated by the source are
suppressed by at least 70dB. Place the filter between
the input of the EV kit and the signal source, making
sure that the proper terminations are being used for this
particular filter.
Connect a spectrum analyzer to VOUT. Set the center
frequency for 40MHz and the span for 50MHz or more.
Adjust the reference level so that the fundamental
(20MHz tone) is within 5dB to 15dB of the reference
level. If the fundamental is less than 5dB below the refer -
ence level, the harmonic distortion of the spectrum ana -
lyzer will prevent accurate measurement of the distortion.
To set the gain state, type the number “7” and press the
Enter key on the PC. You will be prompted to enter the
gain state. Type “30” and press Enter. Place the device
in low-noise mode by typing “4” and pressing Enter.
Measure the level of the fundamental, second, and
third harmonics on the spectrum analyzer. These read -
ings have units of dBm. To convert from dBm to dBmV
in a 50Ω system, use the following equation:
dBmV = dBm + 47dB (50Ω system)
Add 3.5dB to the converted value to arrive at the cor -
rect output voltage, in dBmV, for a 75
Ω
load. The gain
can now be calculated in dB, and the harmonic distor -
tion can be calculated in dBc.
Now place the device in high-power mode. Type “3” on
the PC and press the Enter key. This will increase the
gain by approximately 16dB. The steps taken above
can be repeated to solve for gain and harmonic distor -
tion in high-power mode.
The MAX3532 evaluation board can serve as a guide
for your board layout. Particular attention has been paid
to the output circuit prior to the transformer and the DC
supply trace to pins 29 and 30. The traces leading from
output pins 33 and 34 must be as short as possible and
absolutely symmetrical to reject second harmonics.
Additionally, keep the back-termination resistors as
close to the device as possible to minimize the effects
of inductance on the device’s low output impedance.
Since the device can draw close to 100mA when
swinging the maximum signal, the supply trace to pins
29 and 30 must be as wide as practical to minimize
resistive loss.
Ground inductance and supply decoupling loop induc -
tance degrade distortion performance. Therefore,
ground plane connections to V
EE
(pin 26) and V
EE2
(pin
31) should be made with multiple vias if possible.
Returning supply decoupling capacitors for pins 29
and 30 directly to pins 26 and 31, respectively, is
recommended. Otherwise, use multiple vias to the
ground plane.
Evaluates: MAX3532
†
Layout Considerations
Analysis
_______________________________________________________________________________________
3
MAX3532
†
VCC3
3
2
JU7
VCC3
3
J5–6
3
1
2
JU8
1
R19
OPEN
1
GND
SHDN
GND
TXEN
1
34
2
3
4
32
31
30
VCC2
VCC
*C7
0.001µF
29
28
27
26
25
24
23
22
21
20
SCLK
SDA
19
JU2
JUMPER
2
1
J5–3
R14
100k
VCC3
R15
100k
J5–15
*REV B MISLABELED AS R21
J5–10
J5–7
J5–13
J5–4
R17
OPEN
JU3
JUMPER
2
1
R18
OPEN
C4
0.001µF
C2
0.1µF
R1
51
C3
0.1µF
R4
8.2Ω
33
R2
OPEN
5
VOUT-
VOUT+
GND3
VEE2
VCC2
VCC
VIN+
VIN-
VEE
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
VEE1
GND
GND
VCC1
GND
GND
GND
CS
2
T1
OPEN
3
OPEN
4
5
6
7
8
9
10
11
C1
0.1µF
13
14
15
16
JU1
JUMPER
2
1
17
18
R16
OPEN
12
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
36
35
R3
8.2Ω
R5
24Ω
J4
VOUT
R20
OPEN
2
JU6
1
3
2
VCC
VCC1
VCC2
VCC3
JU5
1
FERRITE
B1
L1, 1.2µH
L2, 1.2µH
L3, 1.2µH
L4, 1.2µH
C6
0.1µF
J5–5
MAX3532 Evaluation Kit
Figure 1. MAX3532 EV Kit Schematic
U1
MAX3532
J1
VIN
J5–18
J5–19
J5–20
J5–21
J5–22
J5–23
J5–24
J5–25
VCC1
J5–2
4
+5V
C5
10µF
10V
GND
J5–1
R6
J5–8
R7
J5–9
R8
J5–11
R9
J5–12
R10
J5–14
R11
J5–16
R12
_______________________________________________________________________________________
J5–17
R13
MAX3532 Evaluation Kit
Evaluates: MAX3532
†
1.0"
1.0"
Figure 2. MAX3532 EV Kit Component Placement Guide—
Component Side
Figure 3. MAX3532 EV Kit Component Placement Guide—
Solder Side
_______________________________________________________________________________________
5
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