CMX991 Datasheet, PDF (28/56 Pages) CML Microcircuits – Two-mode demodulator

RF Quadrature Transceiver / RF Quadrature Receiver
CMX991/CMX992
b5 b4
x 0 I/Q Mode: I and Q channel can be enabled by bits in Rx Control
Register.
0 1 IF Mode: only the I channel output and I channel differential
amplifier can be powered up using the Rx Control Register.
1 1 IF Mode: only the Q channel output and Q channel differential
amplifier can be powered up using the Rx Control Register.
General Control Register b3 and b2
VCO amplifier Negative Resistance (NR) control for optimum phase noise performance. These
bits control the NR (magnitude of the negative transconductance) of the on-chip VCO NR
amplifier. The NR minimum mode would thus be used with the lowest Q external tank circuit and
NR maximum with the highest Q one.
b3 b2
0 0 NR maximum
0 1 NR intermediate value
1 0 NR intermediate value
1 1 NR minimum
6.2.2 General Control Register
8-bit read-only
C-BUS address $E1
This register reads the value in register $11, see section 6.2.1 for details of bit functions.
6.3 Rx Control Register (CMX991/CMX992)
6.3.1 Rx Control Register: C-BUS address $12
8-bit write-only
This register controls general features of the receiver such as Powersave.
All bits of this register are cleared to ‘0’ by a General Reset command.
Bit:
7
6
5
4
3
Mix Pwr
I/Q Pwr
Amp Pwr
SLI Pwr
LNA
2
DIV2
1
DIV1
0
VBIAS
Rx Control Register b7 - b3 and b0
These bits control power up/power down of the various blocks of the IC.
In all cases ‘1’ = power up, ‘0’ = power down.
b7
Enable receiver 1^st mixer
b6
Enable IF amplifier/VGA stage, I/Q mixers, baseband filters
b5
Enable baseband differential amplifiers
b4
Enable SLI amplifier
b3
Enable LNA control signal (output pin LNAON)
b0
Enable V_BIAS (bias voltage on pin 43)
 2015 CML Microsystems Plc
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