Evaluate: MAX2640/MAX2641
MAX2640/MAX2641 Evaluation Kits
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Quick Start
The MAX2640/MAX2641 EV kits are fully assembled
and factory tested. Follow the instructions in the
Connections and Setup
section for proper device
evaluation.
Test Equipment Required
This section lists the recommended test equipment to
verify operation of the MAX2640/MAX2641. It is intend-
ed as a guide only, and some substitutions are possi-
ble.
• One RF signal generator capable of delivering at
least 0dBm of output power up to 2.5GHz
(HP8648C, or equivalent)
• An RF spectrum analyzer that covers the operating
frequency range of the MAX2640/MAX2641 as well
as a few harmonics (HP8561E, for example)
• A power supply capable of up to 100mA at +2.7V to
+5.5V
• An optional ammeter for measuring the supply cur-
rent
• Two 50Ω SMA cables
• (Optional) A noise figure meter (HP8970B, for exam-
ple)
• (Optional) Network analyzer (HP8753D, for exam-
ple) to measure return loss and gain
Connections and Setup
Checking Power Gain
This section provides a step-by-step guide to operating
the EV kits and their function.
1) Connect a DC supply set to +3V (through an amme-
ter, if desired) to the V
CC
and GND terminals on the
EV kit.
2) Set the generator for an output frequency of
900MHz for the MAX2640 and 1900MHz for the
MAX2641 at a power level of -34dBm. Connect one
RF signal generator to the RFIN SMA connector.
3) Connect a spectrum analyzer to the RFOUT SMA
connector on the EV kit. Set it to a center frequency
of 900MHz for the MAX2640 and 1900MHz for the
MAX2641, a total span of 200MHz, and a reference
level of -10dBm.
4) Turn on the DC supply. The supply current should
read approximately 3.5mA for either the MAX2640
or MAX2641 (if using an ammeter).
5) Activate the RF generator’s output. A signal on the
spectrum analyzer’s display should indicate a typi-
cal gain of 15.1dB for the MAX2640 and 14.4dB for
the MAX2641 after accounting for cable and board
losses. Table EV1 lists board losses at specific fre-
quencies.
6) (Optional) Another method for determining gain is
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 network analyzer manufacturer’s user
manual for setup details.
Checking Noise Figure
Noise figure measurements on low-noise devices such
as the MAX2640/MAX2641 are extremely sensitive to
board and lab setup losses and parasitics. There are
many techniques and precautions for measuring a
noise figure below 1dB. Detailed explanation of these
items goes beyond the scope of this document. For
more information on how to perform this level of noise
figure measurement, refer to the noise figure meter
operating manual as well as the Hewlett Packard appli-
cation note # 57-2 “Noise Figure Measurement
Accuracy.”
Layout Considerations
A good PC board layout is an essential part of an RF
circuit design. The EV kit PC board can serve as a
guide for laying out a board using the MAX2640/
MAX2641. Generally, each V
CC
node on the PC board
should have its own decoupling capacitor. This mini-
mizes supply coupling from one section of the IC to
another. A star topology for the supply layout, in which
each V
CC
node on the circuit has a separate connec-
tion to a central V
CC
node, can further minimize cou-
pling between sections of the circuit board.
Modifying the EV kit
The MAX2640 EV kit is factory-configured for operation
at 900MHz and is easily configured to operate from
400MHz to 1500MHz. Use device parameters listed in
Tables 1 and 3 of the MAX2640/MAX2641 data sheet to
determine the proper input and output matching compo-
nents at other frequencies. To evaluate the MAX2641 at
frequencies other than the factory configured 1900MHz,
use device parameters listed in Tables 2 and 4 of the
MAX2640/MAX2641 data sheet to determine the proper
input and output matching components. Table 1 lists
recommended matching component values for the
MAX2641 at 1575MHz and 2450MHz.
The MAX2640/MAX2641 are designed for AC-coupled
operation. When determining matching components for
other frequencies, ensure that a DC-blocking capacitor
is part of the matching network.
