CMX991 Datasheet, PDF (27/56 Pages) CML Microcircuits – Two-mode demodulator

RF Quadrature Transceiver / RF Quadrature Receiver
CMX991/CMX992
6.1 General Reset Command (CMX991/CMX992)
6.1.1 General Reset Command
(no data)
C-BUS address $10
This command resets the device and clears all bits of all registers. The General Reset command places
the device into powersave mode.
Whenever power is applied to the DVDD pin, a built in power-on-reset circuit ensures that the device
powers up into the same state as follows a General Reset command. The RESETN pin on the device will
also reset the device to the same state.
6.2 General Control Register (CMX991/CMX992)
6.2.1 General Control Register:
8-bit write-only
C-BUS address $11
This register controls general features of the device.
All bits of this register are cleared to ‘0’ by a General Reset command.
Bit:
7
En Bias
6
5
4
3
2
1
0
IFH
Chan Sel Rx Mode VCO_NR2 VCO_NR1 VCO_Buff VCO_NR
En
En
General Control Register b7, b1 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 bias generator.
b1
Enable VCO buffer
b0
Enable VCO NR amplifier. (When disabled the amplifier is bypassed to
support the application of an external IF LO signal.)
General Control Register b6
IF Control bit, this applies to Tx and Rx intermediate frequencies:
for IF > 75MHz then set IFH = ‘1’, for IF < 75MHz use IFH = ‘0’.
General Control Register b5 and b4
Output Mode Control
These bits control the output mode of the receiver. The Rx Mode bit determines if the output mode
is I/Q or IF. In I/Q mode both receiver output channels are enabled and the Chan Sel bit has no
effect. In IF mode only one of the receiver output channels is enabled, as selected by the Chan Sel
bit.
NOTE: In IF Mode the I or Q baseband amplifier is also selected by the Chan Sel bit, i.e. only one of the
baseband differential amplifiers can be powered up using the Amp Pwr bit in the Rx Control
Register.
 2015 CML Microsystems Plc
27
D/991_992/20