CMX991 Datasheet, PDF (29/56 Pages) CML Microcircuits – Two-mode demodulator

RF Quadrature Transceiver / RF Quadrature Receiver
CMX991/CMX992
Rx Control Register b2 and b1
RF LO Divider control.
b2 b1
0 0 RF MIXLO input divide by 2
0 1 RF MIXLO input no division
1 0 RF MIXLO input divide by 4
1 1 reserved – do not use
6.3.2 Rx Control Register C-BUS address $E2
8-bit read-only
This read-only register mirrors the value in register $12; see section 6.3.1 for details of bit functions.
6.4 Rx Mode Register (CMX991/CMX992)
6.4.1 Rx Mode Register:
8-bit write-only
C-BUS address $13
This register controls operational modes of the receiver such as gain setting.
All bits of this register are cleared to ‘0’ by a General Reset command.
Bit:
7
IFin
6
Mix Out
5
I/Q Filter
4
Cal En
3
VGA4
2
VGA 3
1
VGA 2
0
VGA 1
Rx Mode Register b7 and b6
Mixer and IF Amplifier signal routing. b7 selects the IF input, b7 = ‘0’ selects IFIP1 and b7 = ‘1’
selects IFIP2. b6 selects the IF output of the Rx 1^st Mixer, b6 = ‘0’ selects MIXOUT1 and b6 = ‘1’
selects MIXOUT2.
b7 b6
0 0 Mixer output on MIXOUT1; IF input on IFIP1 and IFINN
0 1 Mixer output on MIXOUT2; IF input on IFIP1 and IFINN
1 0 Mixer output on MIXOUT1; IF input on IFIP2 and IFINN
1 1 Mixer output on MIXOUT2; IF input on IFIP2 and IFINN
Rx Mode Register b5
Writing b5 = ’1’ I/Q Filter BW = 1MHz; Writing b5 = ’0’ I/Q Filter BW = 100kHz.
Rx Mode Register b4
Enable Calibration Mode: disable LNA and 1^st Mixer when b4 = ’1’; normal operation when b4 = ’0’.
For further details see section 5.2.4.
Rx Mode Register b3 - b0
VGA Control. For further details see section 7.3.2.
b3 b2 b1 b0
1
00
0 VGA= -48dB
0
11
1 VGA = -42dB
0
11
0 VGA = -36dB
0
10
1 VGA = -30dB
0
10
0 VGA = -24dB
0
01
1 VGA = -18dB
 2015 CML Microsystems Plc
29
D/991_992/20