Rainbow Electronics MAX1471 - Manual (Page 22)

MAX1471
Layout Considerations
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 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
of a passive 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 lane below the signal
traces. Also, use low-inductance connections to ground
on all GND pins, and place decoupling capacitors
close to all V
DD or HV IN connections.
315MHz/434MHz Low-Power, 3V/5V
ASK/FSK Superheterodyne Receiver
22 ______________________________________________________________________________________
Table 7. Configuration Register (Address: 0x1)
BIT ID BIT NAME
BIT LOCATION
(0 = LSB)
POWER-UP
STATE
FUNCTION
X Don’t care 7 0 Don’t care.
GAINSET Gain set 6 1
0 = LNA low-gain state.
1 = LNA high-gain state.
For manual gain control, enable the AGC (AGC_EN =
1), set LNA gain state to desired setting, then disable
the AGC (AGC_EN = 0).
FSKCALLSB
FSK accurate
calibration
5 0
FSKCALLSB = 1 enables a longer, more accurate
FSK calibration.
FSKCALLSB = 0 provides for a quick, less accurate
FSK calibration.
DOUT_FSK FSKOUT enable 4 0
This bit enables the FDATA pin to act as the serial
data output in 4-wire mode. (See the Communication
Protocol section.)
DOUT_ASK ASKOUT enable 3 0
This bit enables the ADATA pin to act as the serial
data output in 4-wire mode. (See the Communication
Protocol section.)
TOFF_PS1 Off-timer prescale 2 0
TOFF_PS0 Off-timer prescale 1 0
Sets LSB size for the off timer. (See the Off Timer
section.)
DRX_MODE Receive mode 0 0
1 = Discontinuous receive mode. (See the
Discontinuous Receive Mode section.)
0 = Continuous receive mode. (See the Continuous
Receive Mode section.)