MC13110A/B MC13111A/B
46
MOTOROLA ANALOG IC DEVICE DATA
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R
i
C
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Figure 110. Latch Register Power–Up Defaults
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Register
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Ref
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Mode
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Gain
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SCF
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MSB
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–
–
–
0
0
0
0
1
1
1
LSB
Count
7215
2048
N/A
N/A
31
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15
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–
–
–
–
14
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0
13
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12
1
1
11
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10
9
8
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7
6
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5
1
0
1
1
0
0
4
3
1
2
1
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0
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0
0
0
1
0
1
1
0
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1
0
1
1
1
0
1
0
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0
0
1
1
0
–
0
0
1
1
0
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0
0
0
1
1
á
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1
0
1
0
1
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1
0
1
1
1
1
0
1
0
1
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1
0
1
0
1
1
–
0
0
0
0
1
1
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–
0
0
0
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1
0
0
0
1
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á
SCF
31
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–
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1
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1
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1
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Tx and Rx Counter Registers
The 14 bit Tx and Rx counter registers are used to select
the transmit and receive channel frequencies. In the Rx
counter there is an “IP3 Increase” bit that allows the ability to
trade off increased receiver mixer performance versus
reduced power consumption. With “IP3 increase” = <1>,
there is about a 10 dB improvement in 1 dB compression and
3rd order intercept for both the 1st and 2nd mixers. However,
there is also an increase in power supply current of 1.3 mA.
The power–up default for the MC13111A/B is “IP3 Increase”
= <0>. The register bits are shown in Figure 111.
Reference Counter Register
Reference Counter
Figure 113 shows how the reference frequencies for the
Rx and Tx loops are generated. All countries except the U.K.
require that the Tx and Rx reference frequencies be identical.
In this case, set “U.K. Base Select” and “U.K. Handset
Select” bits to “0”. Then the fixed divider is set to “1” and the
Tx and Rx reference frequencies will be equal to the crystal
oscillator frequency divided by the programmable reference
counter value.
The U.K. is a special case which requires a different
reference frequency value for Tx and Rx. For U.K. base
operation, set “U.K. Base Select” to “1”. For U.K. handset
operation, set “U.K. Handset Select” to “1”. The Netherlands
is also a special case. A 2.5 kHz reference frequency is used
for both the Tx and Rx reference and the total divider value
required is 4096. This is larger than the maximum divide
value available from the 12–bit reference divider (4095). In
this case, set “U.K. Base Select” to “1” and set “U.K. Handset
Select” to “1”. This will give a fixed divide by 4 for both the Tx
and Rx reference. Then set the reference divider to 1024 to
get a total divider of 4096.
Figure 111. Rx and Tx Counter Register Latch Bits
14–b Tx Counter
MSB
LSB
14–b Rx Counter
MSB
LSB
Tx Counter Latch
0
0
IP3
Increase
0
Rx Counter Latch
Figure 112. Reference Counter Register
12–b Ref Counter
MSB
LSB
U.K.
Handset
Select
U.K.
Base
Select
0
0