Circuit Descriptions and Serial Control Information ...... 3
Control bits
Element
Notes
28 29 30
VCO Drive Attenuator I
0
1
0
1
0
1
0
1
0
0
1
1
0
0
1
1
0
0
0
0
1
1
1
1
– Gain Set
-22.4dB
-19.2dB
-16.0dB
-12.8dB
-9.6dB
-6.4dB
-3.2dB
0dB
An in-line control attenuator for the VCO Tx channel
drive output.
This channel is also selected as Audio Output (Rx)
under the control of bit 36. This attenuator can be
used in a volume control application.
31
0
1
VCO Drive Attenuator II
An in-line control attenuator for the VCO Tx channel
drive output. As an example, when bits 28 to 31 are
set to “0,” the gain set is -48.0dB (-22.4 + -25.6).
– Gain Set
-25.6dB
0dB
32 33 34 35
VCO Drive Amplifier
The in-line control amplifier/attenuator for the VCO
Tx channel drive output.
This channel is also selected as Audio Output (Rx)
under the control of bit 36. This amplifier can be
used in a volume control application.
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
– Gain Set
-2.75dB
-2.50dB
-2.25dB
-2.00dB
-1.75dB
-1.50dB
-1.25dB
-1.00dB
-0.75dB
-0.50dB
-0.25dB
0dB
0.25dB
0.50dB
0.75dB
1.00dB
27 36
VCO Drive (Tx)
Output
Bias
VCO Ref (Tx)
Output
Bias
Audio Output
(Rx)
0
0
1
1
0
1
0
1
Bias
Enabled
Bias
Bias
Enabled
Enabled
Bias
Enabled
Enabled
Enabled
The Drive and Ref. paths are powersaved by Bits 45 and 46 in the “Total Powersave” or
“Listening Powersave” conditions. When making internal changes it is recommended that these
outputs are disconnected (placed in a bias condition) from the relevant output (load) circuitry.
37 38 39
Squelch Filter (Gain)
The squelch function is set by bits 45 & 46
(Squelch Source Selection).
The centre frequency gain of this element is 35dB,
data selected gain variations (-3.0dB to 4.0dB) are
around this value.
0
1
0
1
0
1
0
1
0
0
1
1
0
0
1
1
0
0
0
0
1
1
1
1
– Gain Set
-3.0dB
-2.0dB
-1.0dB
0dB
1.0dB
2.0dB
3.0dB
4.0dB
40
0
1
Squelch Filter (Narrow/Wide)
For use in wide or narrow channel systems.
The squelch function is set by bits 45 & 46
(Squelch Source Selection).
– Narrow
– Wide
(ƒc ≈ 18kHz ± 6.5kHz).
(ƒc ≈ 25kHz ± 8.5kHz).
Reference ...... Figure 4
8
CMLMICRO [ CML MICROCIRCUITS ]
