CMX993/CMX993W 30MHz – 1GHz Quadrature Modulator
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COMMUNICA TION SEMICONDUCTORS D/993/12 May 2021 Provisional Issue This document describes two separate, high performance, RF quadrature modulator ICs: The standard CMX993 and the wide bandwidth CMX993W product variant. 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 Input Amplifiers Filter/Interface Amplifiers 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 I/Q Mixer and Gain Control Control Interface 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

Quadrature Modulator

Quadrature Modulator Changes  Section 4.3 – corrected Figure 5 and typo in manufacturer’s part number.  Gain steps variation specified  LO input level specified to -20dBm for operation above 200MHz.  Editorial corrections  Extra information on third order intermodulation added.  Note added for clarification in Figure 4 / Figure 4a.  Added note 32 to AC Parameters section, identifying a drop in gain and output power below a frequency of 100MHz - typically 4dB down at 30MHz.  Differential Amplifier connections in Figure 4 and Figure 4a corrected.  Operating characteristics clarified...

Quadrature Modulator Input Amplifier Filter Amplifier Divide by 2 or Divide by 4 MODQP MODQN MOP Mixer Gain Control MODIN MODIP C-BUS Control Interface Input Amplifier Filter Amplifier CDATA CSN SCLK RESETN Figure 1 CMX993 Block Diagram Input Amplifier Filter Amplifier MODQP MODQN MOP Mixer Gain Control MODIN MODIP Filter Amplifier C-BUS Control Interface Input Amplifier CDATA CSN SCLK RESETN Figure 1a CMX993W Block Diagram

Quadrature Modulator Signal List Signal Type A2QN A2QO NC MODQP MODQN NC MON MOP NC MODIN MODIP NC A2IO A2IN A2IP A1IO A1IN A1IP VCC1 VCC2 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...

Quadrature Modulator Signal Type NC NC VDD VDDIO SCLK CDATA CSN RESETN DVSS VCC7 A1QP A1QN A1QO A2QP NC NC Power Power I/P I/P I/P I/P Power Power I/P I/P O/P I/P reserved, do not connect to this pin reserved, do not connect to this pin Digital supply Supply voltage for digital control interface C-BUS serial clock C-BUS command data input C-BUS enable General reset (Reset when pin is held LOW) Digital ground (0V) Analogue supply Amplifier 1 positive input (Q channel) Amplifier 1 negative input (Q channel) Amplifier 1 Output (Q Channel) Amplifier 2 positive input (Q channel) This pad must be...

Quadrature Modulator External Components Power Supply Decoupling The CMX993/CMX993W has separate supply pins for the analogue and digital circuitry; a 3.3V nominal supply is recommended for all circuits but a different voltage for VDDIO may be used (see section 5.4). R9 Digital Ground for VDDIO and VDD Resistors 5%, capacitors and inductors 20% unless otherwise stated Note: It is expected that low frequency interference on the 3.3V supply will be removed by active regulation; a large capacitor is an alternative but may require more board space and so may not be preferred. It is...

Quadrature Modulator Quadrature Modulator Typical values for the quadrature modulator output circuits are shown in Figure 3/Table 3 and typical configuration and values for the input circuits in Figure 4/4a and Table 4. Concerning Figure 3, the transformer T1 should be located close to the CMX993/CMX993W and tracks from the MOP and MON pins to T1 should be as close to equal in length as possible, preferably with a symmetrical layout. The decoupling capacitor (C1) should be close to the centre tap of T1. Note: Details of a simpler alternative output configuration are provided in an...

Quadrature Modulator Q channel input amplifier Q channel filter amplifier Bandgap I channel filter amplifier I channel input amplifier Figure 4 CMX993 Modulator and Input/Filter Amplifier Typical Configuration LO Input R5 Q channel input amplifier Q channel filter amplifier Note: The modulation signals may be connected to the modulator via either the MODxN or MODxP inputs as long as the connection is the same for both I and Q channels. I channel filter amplifier I channel input amplifier Figure 4a CMX993W Modulator and Input/Filter Amplifier Typical Configuration