Datasheet

MAX7042
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 radia-
tion. 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, 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
passive component. For example, a 0.5in trace con-
necting a 100nH inductor adds an extra 10nH of induc-
tance 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.
308MHz/315MHz/418MHz/433.92MHz
Low-Power, FSK Superheterodyne Receiver
______________________________________________________________________________________ 15
31 30 29 28 27 26
910 11 12 1314 15
18
19
20
21
22
23
24
7
6
5
4
C13
C14
C15
C6
X1
C16
RF INPUT
C7
L1
RSSI
XTAL2
XTAL1
AVDD
8
LNAIN
3.0V
LNASEL
DATA
HVIN
V
DD
V
DD
FSEL2
FSEL1
EN
LNASEL
DATA
FSEL2
FSEL1
EN
DVDD
DGND
DF
OP+
DS+
DS-
PDMAX
17
PDMIN
IFIN-
AGND
16
IFIN+
MIXOUT
MIXIN-
EXPOSED PAD
MIXIN+
LNAOUT
LNASRC
L3
L2
GND
Y1
OUTIN
V
DD
V
DD
C10
C12
C11 C8
C9
RSSI
C2C1
C4
C5
R1
C3
V
DD
MAX7042
Typical Application Circuit