Modulator Translates Baseband IQ Into RF Signals

TO SATISFY BOTH WIRELESS DATA and two-way radio systems, an RF quadrature modulator supports a wide range of modulation types through its in-phase/quadrature (I/Q) architecture. The CMX993 general-purpose, RF quadrature modulator covers 100 MHz to 1 GHz. It operates at +3.3 VDC and features a noise floor of 155 dBm/Hz and wideband noise of 148 dBc/Hz offset 5 MHz from the carrier. It offers 30 dB of gain control in 2.5-dB steps with 10-microsecond gain switching speed. The modulator consists of two integrated and matched double-balanced mixers driven from a buffered-quadrature-split local oscillator (LO) with drive requirements of just 15 dBm. The LO frequency is divided by either 2 or 4 with the mixers forming an in-phase/quadrature (I/Q) vector modulator with programmable gain stages. The modulator's inputs can be driven single ended or differentially for optimum performance. A digital control interface, dubbed the C-BUS (SPI-compatible interface), allows gain control as well as the power management of individual internal blocks.

CML Microcircuits USA, Inc., 465 Corporate Square Dr., Winston-Salem, NC 27105; (336) 744- 5050, FAX: (336) 744-5054, Internet: www.cmlmicro.com.

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