Datasheet
Peak Detector
The peak-detector output (PDOUT), in conjunction with
an external RC filter, creates a DC output voltage equal
to the peak value of the data signal. The resistor pro-
vides a path for the capacitor to discharge, allowing the
peak detector to dynamically follow peak changes of
the data-filter output voltage. For faster data slicer
response, use the circuit shown in Figure 4. For more
details on hysteresis and peak-detector applications,
refer to Maxim Application Note 3671,
Data Slicing
Techniques for UHF ASK Receivers
.
Layout Considerations
A properly designed PCB 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 radiation.
At high frequencies, trace lengths that are on the order
of λ/10 or longer act as antennas.
Keeping the traces short also reduces parasitic induc-
tance. Generally, 1 inch of a PCB trace adds about
20nH of parasitic inductance. The parasitic inductance
can have a dramatic effect on the effective inductance
of a passive component. For example, a 0.5 inch trace
connecting a 100nH inductor 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 power-supply pins.
Control Interface Considerations
When operating the MAX7034 with a +4.5V to +5.5V
supply voltage, the SHDN pin can be driven by a
microcontroller with either +3.0V or +5V interface logic
levels. When operating the MAX7034 with a +3.0V to
+3.6V supply, only +3.0V logic from the microcontroller
is allowed.
MAX7034
315MHz/434MHz ASK Superheterodyne
Receiver
11
DATA
SLICER
R1
25
DATAOUT
20
DSN
19
DFO
23
DSP
C8
MAX7034
DATA
SLICER
R3
R2
R*
R1
25
DATAOUT
*OPTIONAL
23
DSP
19
DFO
20
DSN
C8
MAX7034
Figure 3. Generating Data Slicer Hysteresis
DATA
SLICER
25kΩ
25
DATAOUT
20
DSN
19
DFO
26
PDOUT
23
DSP
MAX7034
47nF
Figure 4. Using PDOUT for Faster Startup
Figure 2. Generating Data Slicer Threshold