MAX2181 Evaluation Kit
Evaluates: MAX2181
General Description
The MAX2181 evaluation kit (EV kit) simplifies evalua-
tion of the MAX2181 FM low-noise amplifier. The EV kit
enables testing of the device’s features and performance
and does not require additional support circuitry or
software. The signal input and output use SMA connectors to
facilitate connection of RF test equipment.
The EV kit is fully assembled with the device on board and
incorporates input matching components for the U.S. FM
broadcast band.
Quick Start
Required Test Equipment
● RF signal generator (or generators) capable of
delivering a signal in the 76MHz to 162.5MHz (FM)
range at a power level of -34dBm.(A higher power
source is required to measure distortion performance.
See the
Measurements
section for more details)
● RF spectrum analyzer that covers the operating
frequency range
● DC power supply capable of supplying +6V to +24V
● 50Ω cables with SMA connectors
● Ammeter to measure supply current (optional)
● Noise-figure meter to measure NF (optional)
● Network analyzer to measure gain and return loss
(optional)
Features
●
Easy Evaluation of the MAX2181
●
+6V to +24V Single-Supply Operation
● RF Input and Output Matched to 50Ω
●
Proven PCB Layout
●
Fully Assembled and Tested
Connections and Setup
Checking Gain
The EV kit is fully assembled and factory tested. Follow
the steps below for proper device evaluation in the default
configuration.
1) Connect a DC supply with its output disabled (preset
to +10V) to the VBATT and GND terminals (through an
ammeter, if desired) on the EV kit.
2) Set the RF generator to the desired fre-
quency at a power level of -37dBm. Disable the
generator’s output and connect it to the FMIN SMA
connector on the EV kit.
3) Connect an SMA cable from the FMOUT SMA connec-
tor to the input of the spectrum analyzer.
4) Turn on the DC supply. The supply current should read
approximately 56mA.
5) Activate the RF generator’s output. The signal on the
spectrum analyzer’s display should indicate a typical
Ordering Information
appears at end of data sheet.
19-6884; Rev 0; 12/13
MAX2181 Evaluation Kit
Evaluates: MAX2181
gain, as shown on the MAX2181 IC data sheet after
accounting for cable and board losses.
6) Optional: Another method of determining gain is by
using a network analyzer. This has the advantage
of displaying gain versus a swept frequency band,
in addition to displaying input and output return loss.
Refer to the user manual of the network analyzer for
setup information.
Note:
Depending on the settings of
the device’s maximum gain and power detector, the
AGC loop can become active for input power levels
as low as -24dBm. To ensure consistent results are
obtained, the stimulus level of the network analyzer
should be no greater than -34dBm, ensuring that the
gain is unaffected by the AGC loop.
Distortion
Two-tone distortion of the amplifier can be measured
using a power combiner to couple the signals from two
generators into FMIN on the EV kit. During closed-loop
operation, as the signal levels increase, the device’s
input impedance is reduced. At the upper end of the input
signal level range, where each tone can be greater than
120dBµV, this reduced impedance could create distor-
tion within the signal generators. For accurate distortion
measurement, the input of the EV kit should be
isolated from the signal generators and power combiner.
This can be accomplished using a ferrite isolator.
Layout Considerations
Electrical
At high-signal-level conditions, the RF currents flowing in
the device can induce voltages in the PCB ground plane,
known as “ground bounce.” To avoid unwanted spurious
products due to ground bounce, proper grounding tech-
niques must be followed.
Detailed Description of Hardware
Test Points
The MAX2181 signal path includes a power detector and
AGC loop, which can be adjusted for maximum gain and
AGC threshold. In addition, the AGC loop can be overrid-
den by applying an external voltage to the FMAGC pin.
Table 1 describes how to control the performance of the
device using the test points on the EV kit.
Thermal
The device is designed to meet data sheet specifications
at supply voltages up to +15V and to function at supply
voltages up to +24V. Under these conditions, a significant
amount of power must be dissipated by the device. This
requires the application PCB to provide a low thermal
impedance path to a thermal ground.
The EV kit PCB design accounts for this by providing
an array of thermal vias in the ground plane and a wide
top metal trace connecting the package pad to a nearby
screw. Adjacent pins 5-7 and 14-16 are all grounded,
which allows the wide trace.
Measurements
Noise
Noise figure can be measured using a NF meter. Because
of the large number of FM broadcast signals that might be
present, this measurement should take place with the EV
kit in a screen box or other type of RF shield.
Table 1. Control Performance with Test Points
TEST POINT
ANTSENSE
FMAGC
FMDET
FMGAIN
LDO
FUNCTION
Antenna sense
FM AGC loop control
voltage
FM AGC threshold
FM gain control
Regulated voltage
DESCRIPTION
Disables the device and sets the supply current to 20mA (typ) if the antenna fault is
detected. Refer to the MAX2181 IC data sheet.
Applying a DC control voltage to FMAGC allows the user to override the AGC loop. 0V
gives maximum gain; 5V gives minimum gain.
Sets the FM AGC threshold. Refer to the MAX2181 IC data sheet. Default value on the
EV kit is 99dBµV (typ) referred to the FMOUT SMA connector (R4 = 43kΩ).
Sets the maximum value of FM gain (FMAGC = 0V). Default setting on the EV kit is
6dB (typ) referred to the FMOUT SMA connector (R2 = 10kΩ).
Allows measurement of internal regulator voltage.
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MAX2181 Evaluation Kit
Evaluates: MAX2181
Component List
DESIGNATION
ANTSENSE,
FMAGC,
FMDET,
FMGAIN, LDO,
VBATT (x2)
C3, C9
QTY
DESCRIPTION
DESIGNATION
L2
7
Test points
L3
2
0.1µF ±10% ceramic capacitors
(0603)
Murata GRM188R71E104K
2700pF ±10% ceramic capacitor
(0603)
Murata GRM1885C1H272K
0.47µF ±10% ceramic
capacitors(0603)
Murata GRM188R71C474K
100pF ±5% ceramic capacitor
(0603)
Murata GRM1885C1H101J
33pF ±5% ceramic capacitor
(0603)
Murata GRM1885C1H3300J
10µF ±10% tantalum capacitor
(C case)
AVX TAJC106K035R
10µF ±10% tantalum capacitor
(A case)
AVX TAJA106K010R
Connectors
Test points
470nH ±5% inductor (0603)
Murata LQW18ANR47J00
L4
R1
R2
R3
R4
R6
R7
R8
U1
—
—
—
—
—
—
—
—
*EP
= Exposed pad.
1
1
1
1
1
1
1
1
1
1
1
10
5
1
1
1
1
1
QTY
0
DESCRIPTION
Not installed, ±5% midi spring
air-cored inductor
Coilcraft 1812SMS-R10JL
82nH ±5% inductor (1008)
Murata LQW2UAS82NJ00
27nH ±5% inductor (0603)
Murata LQW18AN27NJ00
43kΩ resistor
61.9Ω resistor
105Ω resistor
20kΩ resistor
0Ω resistor
100kΩ resistor
10kΩ resistor
FM automotive low-noise amplifier
(16 TQFN-EP*)
Maxim MAX2181
Metal heat sink
Screws
Standoffs
Brown box, 9 3/16in x 7in x 7/8in
ESD bag, 4in x 6in with ESD logo
Pink foam, 12in x 12in x 5mm
Web instructions
PCB: MAX2181 EVALUATION
KIT#
C4
1
C5
1
C6
1
C7
1
C10
1
C11
FMIN, FMOUT
GND
L1
1
2
2
1
Component Suppliers
SUPPLIER
AVX North America
Keystone Electronics Corp.
Murata Americas
PHONE
864-967-2150
800-221-5510
800-241-6514
www.avx.com
www.keyelco.com
www.murataamericas.com
WEBSITE
Note:
Indicate that you are using the MAX2181 when contacting these component suppliers.
www.maximintegrated.com
Maxim Integrated
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3
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