CMX7861 FirmCODEC® Programmable Baseband Interface
CMX7861
Output1_Coarse_Gain [6:0]
Output_Config [0]
Output1_Coarse
_Gain [15]
x2
Output_Config
[1]
OUTPUT 1
(or I output for
an I/Q-based
system)
OUTPUT1N
OUTPUT1P
DAC
DAC
1
1
Filter
Output2_Coarse_Gain [6:0]
Output_Config [2]
Signal_Control
[7:6]
Output2_Coarse
_Gain [15]
x2
Output_Config
[2]
OUTPUT 2
(or Q output for
an I/Q-based
system)
OUTPUT2P
OUTPUT2N
DAC
DAC
2
2
Filter
Signal_Control
[5:4]
Output_Config [5]
OUTPUT4P
OUTPUT4N
Output_Config [7]
Output3_Coarse
_Gain [15]
8Ohm
driver
Output_Config
[8]
Output 3/4
Pwr
x2
OUTPUT3
32Ohm
driver
Output_Config [4]
Output3_Coarse_Gain [5:0]
Figure 5 Analogue Output Routing
The registers that control analogue output signal routing are described in the following sections:
9.1.10 Signal Control - $61 write
9.1.21 Output 1 - 4 Configuration - $B3 write
9.1.22 Output 1 and 2 Coarse Gain - $B4, $B5 write
Include Output3 coarse gain register here when it is defined
5.3.2 Output Reconstruction Filter – (I/Q mode)
When output 1 (or I) and output 2 (or Q) are used as I/Q outputs, internal reconstruction filtering is
provided with four selectable bandwidths (-3dB point shown in section 9.1.21). The bandwidth of the
internal reconstruction filter may be selected using the Output 1 - 4 Configuration - $B3 write or Signal
Control - $61 write registers.
To complete the output reconstruction filter one of the following external RC networks should be used for
each of the differential outputs. The external RC network should have a bandwidth that matches the
bandwidth of the selected internal reconstruction filter.
2012 CML Microsystems Plc
Page 13
D/7861_FI-1.x/2
CMLMICRO [ CML MICROCIRCUITS ]
