5) Connect the RF output of the EV kit to the spectrum

analyzer using an SMA cable. Take care to use

quality connector adapters for the spectrum analyz-

er’s input. Avoid the use of BNC-type connectors

due to their high VSWR while operating in the GHz

range.

6) To assist in troubleshooting, verify the correct DC

voltages on the PC board with a multimeter. Use

Table 1 to verify correct node voltage during proper

operation.

Analysis

1) Set the spectrum analyzer’s center frequency to

900MHz, with a span of 30MHz.

2) Set the marker position to the peak level.

3) Read the output power of the center frequency. This

should be nominally -18dBm ±1.3dBm. The output

frequency is equal to the algebraic difference of the

LO and IF frequencies. The power is equal to the

IFIN input power, plus the conversion gain of the

upconverter mixer. The MAX2673 has a typical con-

version gain of 12dB.

Detailed Description

Figure 1 is the schematic for the EV kit as shipped. The

output matching components (L1, L2, C4, and C5) are

optimized for an output frequency of 900MHz.

Capacitor C1 is a DC-blocking capacitor for the LO

input port. To reduce the possibility of noise pickup,

resistor R2 and capacitor C9 form a lowpass filter at the

SHDN pin.

decoupling network. Note the location of each compo-

nent. Capacitor C7, a 10µF tantalum type, is located

and the output pull-up inductor L2. Both of these sup-

ply points need separate bypass capacitors as well as

separate traces on the PCB. This is prudent practice to

curtail crosstalk in high-frequency systems.

Modifying the EV Kit

The MAX2673 EV kit is easily used at output frequen-

cies from 400MHz to 2500MHz. To operate at frequen-

cies other than the factory configuration of 900MHz,

refer to Table 2 for the required component values.

Table 1. Nominal DC Voltages

PIN NUMBER

PIN NAME

NOMINAL DC

VOLTAGE

1

LO

MAX2673 Evaluation Kit

2

_______________________________________________________________________________________

2, 6

GND

0

3

SHDN

4

+2.7V to +5.5V

5

RF OUT

7

IFIN-

+1.37V

8

IFIN+

+1.37V

Table 2. Output Matching Components

vs. RF Output Frequency

REFERENCE

DESIGNATOR

L1

Short

L2

39nH

C4

3300pF

C5

6.8pF

C2, C3, C6, C9

470pF

27nH

18nH

220pF

1.5pF

47pF

RF OUTPUT FREQUENCY

5.6nH

3.9nH

4.7nH

6.8nH

100pF

220pF

1.5pF

1pF

47pF

47pF

400MHz

900MHz

1900MHz 2450MHz