Data Sheet
MGCM02
2. FM Mode. This is used for direct FM modulation of
transmit IF oscillator.
LPC <1:0>
Operation
0
0
1
1
0
1
0
1
Both filters 37.5kHz cut-off
Filter 2 - 37.5kHz, filter 1 - 25kHz
Filter 2 - 25kHz, filter 1 - 37.5kHz
Both filters 25kHz cut-off
These modes are controlled by TX <1:0> - Word 6
Bits 9:8
TX <1:0>
Mode
0
0
1
0
1
TDMA
FM - Differential input
FM - Single-ended input
PDF <1:0>
Operation
X
0
0
1
1
0
1
0
1
No extra filtering
Filter 1 only
Filter 2 only
Both filters
A calibration of the transmit filters can be initialised
by setting TXC - Word 6 Bit 10 to 1. After calibration
the internal register for this bit is reset to 0
The transmit gain can be programmed by TXG<2:0>
- Word 6 Bits 13:11
The dc level for the baseband I and Q outputs can be
selected by RDC - Word 8 Bit 11
TXG <2:0>
Gain (dB)
RDC
Operation
X
0
0
1
1
X
0
1
0
1
1
0
0
0
0
0
3
0
1
Output Bias = 1.25 Volts
Output Bias = Vdd/2
6
9
The VGA<2:0> - Word 8 Bits 5-3, are used to set FM
gain mode and for test purposes.
12
The dc level for the transmit I and Q outputs can be
selected by TDC - Word 8 Bit 12
VGAWD <2:0>
Operation
0
0
0
Standard Mode.
AGC Control for TDMA,
Fixed gain for FM
TDC
Operation
0
1
Output Bias = 1.25 Volts
Output Bias = Vdd/2
1
1
0
AGC Control for FM
The other states are used for test purposes. In
TDMA mode VGAWD should always be set to 000.
Transmit Calibration
Transmit Programming
This is initiated by setting TXC - Word 6 Bit 10 high.
Calibration takes approximately 0.6ms. In order for
the calibration to give the required cutoff, CALCO -
Word 8 Bits 23:16 must be set to 00001100. The
calibration code is then stored in TC<3:0> Word 6
Bits 6:3, and TXC is reset low. If TC<3:0> is
overwritten then a further calibration is required.
MGCM02 has two basic transmit modes.
1. I / Q mode. I and Q signals from baseband digital
to analog converter are filtered and buffered. This
mode is used for IS136 TDMA.
15
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