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PDF CMX993 Data sheet ( Hoja de datos )
| Número de pieza | CMX993 | |
| Descripción | Quadrature Modulator | |
| Fabricantes | Consumer Microcircuits Limited | |
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CML Microcircuits
COMMUNICATION SEMICONDUCTORS
CMX993/CMX993W
30MHz – 1GHz
Quadrature Modulator
D/993/10 February 2013
Provisional Issue
This document describes two separate, high performance, RF quadrature modulator ICs:
The standard CMX993 and the wide bandwidth CMX993W product variant.
Features
Applications
30MHz to 1GHz Operating Frequency
Wide Band Noise –148dBc/Hz
Noise Floor –155dBm/Hz
Programmable 30dB Output Gain Range
+3dBm (PEP) Output Power
Low LO Drive Requirements, -15dBm
Uncommitted Amplifiers for Filtering and
Interfacing
CMX993W – Wide Bandwidth Version
(>50MHz I/Q Bandwidth)
C-BUS (SPI Compatible) Serial Interface
Low Voltage 3.3V Operation
Small 7x7mm VQFN Package (Q3)
+25dBm Equivalent Output IP3
APCO P25, Wireless Data
ISM Transmitters
Digital TV/CATV Modulators
Wireless LAN, Wireless Local Loop
IF or RF Modulators
FSK, GMSK, 4FSK, C4FM
QPSK, QAM, SSB, OFDM,
Multi-carrier Systems
SDR (Software Defined Radios)
WiMAX Systems
OFDM/COFDM Systems
Satellite Communications
Cellular Picocell / Nanocell Systems
RF Channel Bandwidths up to 100MHz
Input Amplifiers
I Channel
Filter/Interface
Amplifiers
Q Channel
I/Q Mixer and Gain Control
I/Q MOD Output
LO Input
Divide by 2
or
Divide by 4
0°
90°
Bandgap
Control
Interface
VREF
C-BUS
1 Brief Description
The CMX993 and CMX993W are integrated, low voltage quadrature (I/Q) modulator ICs suitable for use in
applications operating from 30MHz to 1000MHz. The devices integrate two matched double balanced
mixers driven from a buffered and quadrature split local oscillator. The LO frequency is divided by either 2
or 4. The mixers form an I/Q vector modulator with programmable gain stages offering up to 30dB of gain,
controlled in 2.5dB steps.
Uncommitted low frequency differential amplifiers are provided for users to configure. These may be used
to implement functions such as filtering, differential- to single-ended signal conversion and level shifting.
The CMX993W product variant offers wide-bandwidth operation.
A digital control interface, C-BUS, (an SPI compatible interface) allows gain control as well as power
management of individual internal blocks to optimise system performance. The C-BUS interface operates
from its own supply domain enabling the device to be interfaced to different voltage baseband devices.
The CMX993 and CMX993W devices are supplied in RF optimised VQFN packages.
2013 CML Microsystems Plc
1 page  
Quadrature Modulator
3 Signal List
CMX993/CMX993W
CMX993
Pin No.
-
1
2
3
4
5
6
7
8
9
10
11
12
-
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
CMX993W
Pin No.
1
2
-
3
4
5
6
7
8
9
10
-
11
12
13
14
15
16
17
18
Name
A2QN
A2QO
NC
MODQP
MODQN
NC
MON
MOP
NC
MODIN
MODIP
NC
A2IO
A2IN
A2IP
A1IO
A1IN
A1IP
VCC1
VCC2
19 LON
20 LOP
21 VCC3
22 VCC4
23 VREF
24 BVREF
25 NC
26 NC
27 NC
28 NC
29 VCC5
30 NC
31 NC
32 VCC6
33 NC
34 NC
Signal
Type
I/P
O/P
NC
I/P
I/P
NC
O/P
O/P
NC
I/P
I/P
NC
O/P
I/P
I/P
O/P
I/P
I/P
Power
Power
I/P
I/P
Power
Power
O/P
O/P
NC
NC
NC
NC
Power
NC
NC
Power
NC
NC
Description
Amplifier 2 negative input (Q channel)
Amplifier 2 output (Q channel)
reserved, do not connect to this pin
Modulator input (Q channel)
Modulator input reference (Q channel)
reserved, do not connect to this pin
Modulator negative output
Modulator positive output
reserved, do not connect to this pin
Modulator input reference (I channel)
Modulator input (I channel)
reserved, do not connect to this pin
Amplifier 2 output (I channel)
Amplifier 2 negative input (I channel)
Amplifier 2 positive input (I channel)
Amplifier 1 output (I channel)
Amplifier 1 negative input (I channel)
Amplifier 1 positive input (I channel)
Analogue supply
Analogue supply
Local Oscillator Negative Input (Note: when
differentially driving LOP and LON this LON pin
requires a low impedance dc path to ground
otherwise it may be decoupled to ground)
Local Oscillator Positive Input (Note: this pin
requires a low impedance dc path to ground)
Analogue supply
Analogue supply
Bandgap reference decoupling
Buffered VREF
reserved, do not connect to this pin
reserved, do not connect to this pin
reserved, do not connect to this pin
reserved, do not connect to this pin
Analogue supply
reserved, do not connect to this pin
reserved, do not connect to this pin
Analogue supply
reserved, do not connect to this pin
reserved, do not connect to this pin
2013 CML Microsystems Plc
5
D/993/10
5 Page 
Quadrature Modulator
CMX993/CMX993W
5 General Description
The CMX993 and CMX993W are RF quadrature modulators with additional features such as gain control
and uncommitted differential amplifiers. Detailed block diagrams for the ICs are shown in section 2. The
ICs can support a wide range of modulation formats and standards including TDMA operation.
The following sections describe the functionality of the ICs.
5.1 Quadrature Modulator
The quadrature modulator provides translation from baseband I and Q signals to a modulated RF signal.
The wideband inputs can be driven differentially or single-ended. In the case of single ended operation a
reference voltage equal to the nominal dc level of the modulation must be supplied. The input and filter
amplifiers allow single-ended signals to be translated to an appropriate dc level, one solution for an input
signal with 0V dc bias is shown in Figure 4/4a.
5.1.1 DC Offsets and Carrier Leakage
The modulator inputs (MODIN/MODIP and MODQN/MODQP) are differential and require a common dc
level or common mode voltage. Differences in the bias voltages on the pins will result in an increased level
of carrier present at the output. Care should be taken to minimise offsets, thereby minimising carrier
leakage.
Some systems implement carrier nulling before transmission. This results in a compensation of the small
internal offsets in the modulator and any offsets generated in external circuits. Digital to analogue
converters designed for I/Q systems, e.g. CMX981, often include registers which allow a programmable
offset to be applied to the I/Q signals, making this nulling process straightforward.
5.1.2 Wideband Noise and Gain Control
The wideband noise of this modulator is optimised to ensure a low noise floor at the output, compliant with
common product standards. This stage also provides gain control, which allows the output level to be
adjusted while maintaining the maximum possible signal-to-noise ratio.
To ensure optimum performance the I/Q input signals need to be free from noise. The input bandwidth of
the modulators is quite broad, so any noise on the I/Q signals will get translated to the RF output. Such
noise can generally be removed by simple RC filters, as shown in Figure 4/4a. Careful attention needs to
be paid to the bandwidth of these filters as, if unduly narrow, they can affect the modulation, degrading
image rejection and modulation accuracy.
5.2 Differential Amplifiers
5.2.1 Input Amplifiers
Two differential amplifiers are provided which may be used for signal conditioning, for example conversion
of differential input signals to single ended format, or to provide dc level translation. The amplifiers are
uncommitted, with the differential inputs and the output all available on pins. The stages are low power and
are enabled using the ‘General Control Register’ (see section 6.2). It is not possible to independently
control each amplifier, both are enabled with a common control bit.
2013 CML Microsystems Plc
11
D/993/10
11 Page | ||
| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet CMX993.PDF ] | |
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