MAX7036
300MHz to 450MHz ASK Receiver
with Internal IF Filter
in the RC smoothing circuit between DSP and DSN. This
circuit will provide an instantaneous jump of one-half of
the DSP increase from “no signal” voltage to peak volt-
age, which then decays with the same time constant as
that of the threshold build-up from the RC smoothing cir-
cuit. The DC slicing voltage at DSN is slightly higher (by
the ratio of the two resistors in the circuit) than it would be
without the speed-up circuit. Always provide a capaci-
tive path from the PDOUT pin to ground when using
the peak-detector output.
MAX7036
DATA
FILTER
DATA
SLICER
20
DATAOUT
17
16
DSN
DSP
R1
C4
18
PDOUT
Figure 4. Using PDOUT for Faster Startup
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 frequen-
cies, trace lengths that are λ/10 or longer act as antennas.
Keeping the traces short also reduces parasitic induc-
tance. Generally, 1in of a PCB trace adds about 20nH of
parasitic inductance. The parasitic inductance can have
a dramatic effect on the effective inductance of a pas-
sive component. For example, a 0.5in 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 connections.
Table 2. Component Values
COMPONENT
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
L1
L2
R1
Y1
fRF = 315MHz
4.7pF
100pF
100pF
0.1µF
390pF
180pF
1µF
0.01µF
22pF
10pF
0.1µF
220pF
10pF
10pF
100pF
0.1µF
100nH
27nH
22kΩ
9.8375MHz
fRF = 433.92MHz
2.7pF
100pF
100pF
0.1µF
390pF
180pF
1µF
0.01µF
22pF
10pF
0.1µF
220pF
10pF
10pF
100pF
0.1µF
47nH
15nH
22kΩ
13.55375MHz
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