AIS Baseband IC with/without RF Synthesiser
CMX7032/CMX7042
Table 2 Component Values
R1 100k
R3 100k
C1 18pF
C2 18pF
C16 100pF
C23 10nF
C17 10µF
C18 10nF
C19 10nF
C20 10µF
C21 10nF
C22 10nF
C24 10µF
C25 10nF
C26 10µF
C27 10nF
C28 10µF
R4 100k
C3 10nF
C4 not fitted
C7 100nF
C8 100pF
C9 100pF
C12 100pF
C14 100pF
R5 See note 2
R6 100k
R7 See note 3
R8 100k
R9 See note 4
R10 100k
X1 9.6MHz
See note 1
Resistors 5%, capacitors and inductors 20% unless otherwise stated.
Notes:
1.
X1 can be a 9.6MHz crystal or a 19.2MHz external clock generator. The tracks between the crystal and the
device pins should be as short as possible to achieve maximum stability and best start up performance.
2.
R5 should be selected to provide the desired dc gain (assuming C11 is not present) of the input, as follows:
GAIN = 100k / R5
RX1N
The gain should be such that the resultant output at the RX1FB pin is within the input signal range specified
in 8.1.3.
3.
4.
R7 should be selected to provide the desired dc gain (assuming C13 is not present) of the input as follows:
GAIN = 100k / R7
RX2N
The gain should be such that the resultant output at the RX2FB pin is within the input signal range specified
in 8.1.3.
R9 should be selected to provide the desired dc gain (assuming C15 is not present) of the input as follows:
GAIN
SpareN
= 100k / R9
The gain should be such that the resultant output at the SpareFB pin is within the input signal range
specified in 8.1.3.
5.
6.
Care should be taken in connecting the output of the Limiter-Discriminator device to the Rx input pins of the
CMX7032. The format of the GMSK signal requires that the frequency response of the input circuits extends
to below 10Hz, however the variations in the incoming AIS signals from many different stations require that
the input must rapidly follow the changes in dc and signal levels without de-grading the signal seen at the Rx
input pins.
A single 10µF electrolytic capacitor (C24, fitted as shown) may be used for smoothing the power supply to
both V
pins, providing they are connected together on the pcb with an adequate width power supply
DEC
trace. Alternatively, separate smoothing capacitors should be connected to each V
pin. High frequency
DEC
decoupling capacitors (C3 and C23) must always be fitted as close as possible to both V
pins.
DEC
2012 CML Microsystems Plc
14
D/7032/42_FI1.2/13
CMLMICRO [ CML MICROCIRCUITS ]
