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PDF CMX971 Data sheet ( Hoja de datos )
| Número de pieza | CMX971 | |
| Descripción | Quadrature Modulator | |
| Fabricantes | Consumer Microcircuits Limited | |
| Logotipo |  |
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CML Microcircuits
COMMUNICATION SEMICONDUCTORS
CMX971
Quadrature Modulator
D/971/4 February 2015
Features
20 – 1000MHz RF Output
0dBm Output
25MHz I/Q Bandwidth
Serial Bus or Direct Control Operation
Low Power 3.0V – 3.6V Operation
Small 16-lead VQFN Package
Provisional Issue
Applications
Wireless Data Terminals
HF/VHF and UHF Mobile Radio
Avionics Radio Systems
TXIN
TXQP
TXQN CBUSOFFN
TXIP
RFOUT
RFGND
VCC
Divide by
2 or 4
VSS
CSN/
FREQ2
RDATA/
DIVSET
SCLK/
RESETN
LO LOGND CDATA/ VDD
FREQ1
1 Brief Description
The CMX971 is a high performance quadrature modulator featuring a wide operating frequency range and
attractive power consumption. Control of the CMX971 may be either by serial bus or by direct control (with
reduced functionality). Programmable features include the local oscillator divider ratio (2 or 4). The small,
RF-optimised VQFN package and minimal external components make the device ideal for space-
constrained applications.
2015 CML Microsystems Plc
1 page  
Quadrature Modulator
CMX971
3 Pin and Signal List
3.1 Main Functions
Pin Name
1 TXIP
2 RFOUT
3 RFGND
4 VCC
5 LO
6 LOGND
7 CDATA / FREQ1*
8 VDD
9 SCLK / RESETN*
10 RDATA / DIVSET*
11 CSN / FREQ2*
12 VSS
13 CBUSOFFN
14 TXQN
15 TXQP
16 TXIN
~ EXPOSED METAL PAD
Type
IP
OP
PWR
PWR
IP
PWR
IP
PWR
IP
OP or
IP*
IP
PWR
IP
IP
IP
IP
PWR
Signal Description
Input for baseband transmit I signal (positive)
RF output
Analogue and RF ground
Analogue and RF supply
Input for local oscillator
LO Buffer ground
C-BUS data-in
C-BUS and digital supply
C-BUS clock input
C-BUS data output
C-BUS chip select
C-BUS and digital ground
Disable pin for C-BUS operation. If held low, direct
control pin functions are selected as described in
Table 2 and it enables modulator sections (equivalent
to General Control Register b4 and b0 = ‘1’, see
section 6.2.1). Internal ≈1MΩ pullup resistor.
Input for baseband transmit Q signal (negative)
Input for baseband transmit Q signal (positive)
Input for baseband transmit I signal (negative)
Substrate. Connect to Analogue and RF ground
* Direct control functions for these pins selected if CBUSOFF pin = ‘0’, see Table 2.
Notes: IP
OP
PWR
NC
=
=
=
=
Table 1 Main Pin Functions
Input
Output
Power Connection
No connection – should NOT be connected to any signal
3.2 Direct Control Functions
When C-BUS is held disabled, pins 7, 9, 10 and 11 have the following functions (Table 2). Every time the
CBUSOFFN pin is held low the registers of the device are placed in the RESET state (section 6.1.1)
except ENBIAS and TXEN (see section 6.2.1) which are active. The functions listed in Table 2 are then
controlled by the appropriate pins.
Pin Function
7 FREQ1 – in combination with FREQ2 sets frequency range (see bit 0 of Tx Control
register, section 6.3.1 and section 7.))
9 RESETN – When low puts the device into low power mode. No internal pullup resistor.
10 DIVSET – if low sets mixer input to local oscillator divide by two, if high sets mixer input
to local oscillator divide by four (equivalent to the inverse of bit 6 of General Control
Register, section 6.2.1)
11 FREQ2 – in combination with FREQ1 sets frequency range (see bit 1 of Tx Control
register, section 6.3.1 and section 7.)
Note: local oscillator divide by two and local oscillator divide by four will hereafter be referred to as LO/2
and LO/4 respectively.
Table 2 Direct Control Pin Functions
2015 CML Microsystems Plc
5
D/971/4
5 Page 
Quadrature Modulator
CMX971
6.2 General Control Register
8-bit write-only
6.2.1 General Control Register: C-BUS address $1B
This register controls general features such as powersave.
All bits of this register are cleared to ‘0’ during a General Reset command.
Note:
b0 (TXEN) and b4 (ENBIAS) are high if pin CBUSOFFN is low.
Bit: 7 6 5 4 3 2 1
0 TXDIV 0 ENBIAS 0 0 0
0
TXEN
General Control Register b6, b4 and b0
Writing b6 = ’1’ the LO is divided by 2; writing b6 = ’0’ the LO is divided by 4.
Writing b4 = ‘1’ Enables the internal bias current supplies.
Writing b0 = ‘1’ Enables the quadrature modulator
All other bits are reserved and must be set to ‘0’ for correct operation.
6.2.2 General Control Register
C-BUS address $EB
8-bit read-only
This register reads the value in register $1B, see section 6.2.1 for details of bit functions.
6.3 Control Register
6.3.1 Control Register:
C-BUS address $1E
8-bit write-only
This register controls transmitter features.
All bits of this register are cleared to ‘0’ by a General Reset command.
Bit: 7 6 5 4 3 2 1 0
0 0 0 0 F3 F2 F1 F0
Control Register b7 – b4
These bits are reserved and must be set to ‘0’ for correct operation.
Control Register b3 - b0
These bits optimise the performance of the Transmitter LO path. The best intermodulation
performance is achieved at the lowest control setting (‘0000’) and the best wideband noise can be
achieved at the highest setting (‘1111’).
2015 CML Microsystems Plc
11
D/971/4
11 Page | ||
| Páginas | Total 25 Páginas | |
| PDF Descargar | [ Datasheet CMX971.PDF ] | |
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