pling to AC. The scope now displays a lowpass-fil-
tered square wave at TP3 (filtered analog base-
band data). Use the RF generator’s LF OUTPUT
(modulation output) to trigger the oscilloscope.
7) Monitor the DATA_OUT terminal and verify the pres-
ence of a 2kHz square wave.
Additional Evaluation
1) With the modulation still set to AM, observe the
effect of reducing the RF generator’s amplitude on
the DATA_OUT terminal output. The error in this
sliced digital signal increases with reduced RF sig-
nal level. The sensitivity is usually defined as the
point at which the error in interpreting the data (by
the following embedded circuitry) increases
beyond a set limit (BER test).
2) With the above settings, a 315MHz-tuned EV kit
should display a sensitivity of about -114dBm (0.2%
BER) while a 433.92MHz kit displays a sensitivity of
about -112dBm (0.2% BER). Note: The above sensi-
tivity values are given in terms of average.
3) Capacitors C5 and C6 are used to set the corner
frequency of the 2nd-order lowpass Sallen-Key
data filter. The current values were selected for bit
rates up to 3kbps. Adjusting these values accom-
modates higher data rates (refer to the MAX7033
data sheet for more details).
Layout Issues
A properly designed PC board is an essential part of
any RF/microwave circuit. On high-frequency inputs
and outputs, use controlled-impedance lines and keep
them as short as possible to minimize losses and radia-
tion. At high frequencies, trace lengths that are on the
order of λ/10 or longer can act as antennas.
Keeping the traces short also reduces parasitic induc-
tance. Generally, 1in of a PC board trace adds about
20nH of parasitic inductance. The parasitic inductance
can have a dramatic effect on the effective inductance.
For example, a 0.5in trace connecting a 100nH induc-
tor adds an extra 10nH of inductance or 10%.
To reduce the parasitic inductance, use wider traces
and a solid ground or power plane below the signal
traces. Also, use low-inductance connections to ground
on all GND pins, and place decoupling capacitors
close to all VDD connections.
The EV kit PC board can serve as a reference design for
laying out a board using the MAX7033. All required com-
ponents have been enclosed in 1.25in x 1.25in
2
, which
can be directly “inserted” in the application circuit.
Detailed Description
Power-Down Control
The MAX7033 can be controlled externally using the
SHDN connector. The IC draws approximately 2.5µA in
shutdown mode. Jumper JU1 is used to control this
mode. The shunt can be placed between pins 2 and 3
for continuous shutdown, or pins 1 and 2 for continuous
operation. Remove JU1 shunt for external control. See
Table 1 for the jumper function descriptions.
Evaluates: MAX7033
MAX7033 Evaluation Kit
_______________________________________________________________________________________ 3
Note: Indicate that you are using the MAX7033 when contact-
ing these component suppliers.
