Datasheet

MAX7036 Evaluation Kit
Evaluates: MAX7036
3Maxim Integrated
RF generator amplitude is changed from -115dBm to
0dBm. Note: At an input amplitude of approximately
-60dBm, this DC voltage drops suddenly to about
1.76V and then rises again with increasing input
amplitude. This is normal; the AGC is turning on the
LNA gain-reduction resistor.
4) Capacitors C5 and C18 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 4kbps Manchester. Adjusting these values accom-
modates different data rates (refer to the MAX7036 IC
data sheet for more details).
Layout Issues
A properly designed PCB is essential for any RF/micro-
wave circuit. Keep high-frequency input and output lines
as short as possible to minimize losses and radiation. At
high frequencies, trace lengths that are on the order of
λ/10 or longer can act as antennas.
Both parasitic inductance and capacitance are influ-
ential on circuit layouts and are best avoided by using
short trace lengths. Generally, a 10-mil wide PCB trace,
0.0625in above a ground plane, with FR4 dielectric has
about 19nH/in of inductance and about 1pF/in of capaci-
tance. In the LNA/mixer circuit, where the inductor is on
the order of 20nH and a capacitor is on the order of 3pF,
the proximity of the circuit to the MAX7036 has a strong
influence on the effective component values.
To reduce the parasitic inductance, use a solid ground or
power plane below the signal traces. Also, use low-induc-
tanceconnectionstogroundonallGNDpins,andplace
decouplingcapacitorsclosetoallVDDconnections.
Detailed Description of Hardware
The MAX7036 EV kit provides a proven layout for the
MAX7036. On-board test points are included to monitor
various signals (Table 2).
Power Supply
The MAX7036 can operate from 3.3V or 5V supplies. For
5V operation, remove the shunt from JU1 before connect-
ingthesupplytoVDD.AVDDandDVDDoperatefroman
internallinearregulatorwhenVDD=5V.For3.3Vopera-
tion, connect the shunt on JU1.
IF Signal
Jumper JU3 with one side grounded is provided to monitor
the IF signal. A shunt cannot be used at JU3.
External Frequency Input
For applications where an external frequency is desired
over the crystal frequency, it is possible to remove the
crystal and apply an external frequency through P1.
Capacitor C2 is necessary (use a 0.01µF capacitor).
Table 1. Jumper Table (JU1–JU4)
*Default position.
Table 2. Test Points
JUMPER
SHUNT
POSITION
DESCRIPTION
JU1
Open
DisconnectsAVDDandDVDDfromVDD.Applyupto5VontheVDDpad.Aninternalregulator
providespowertoAVDDandDVDD.
Closed* ConnectsAVDDandDVDDtoVDD.Whenconnected,donotexceed3.3VontheVDDpad.
JU2
1-2*
ConnectsENABLEtoVDD(normaloperation)
2-3 ConnectsENABLEtoGND(shutdown)
JU3 Open* Always keep open. Provides a test point for the IF signal.
JU4
1-2
ConnectsPDOUTtoDSNnodeforfasterdatadetection(ifpopulated)
2-3* ConnectsPDOUTtoGNDthroughR2andC17(ifpopulated)
TEST POINT DESCRIPTION
TP1 Noninverting op-amp input
TP2
DATAOUToutput
TP3 PDOUToutput
TP4 GND