Abstrac
The AD8341 vector modulator performs arbitrary amplitude and phase modulation of an RF signal. Since the RF signal path is linear, the original modulation is preserved. This part can be used as a general-purpose RF modulator, a variable attenu- ator/phase shifter, or a remodulator. The amplitude can be controlled from a maximum of 4.5 dB to less than 34.5 dB, and the phase can be shifted continuously over the entire 360° range. For maximum gain, the AD8341 delivers an OP1dB of8.5 dBm, an OIP3 of 17.5 dBm, and an output noise floor of 150.5 dBm/Hz, independent of phase. It operates over a frequency range of 1.5 GHz to 2.4 GHz.
The baseband inputs in Cartesian I and Q format control the amplitude and phase modulation imposed on the RF input signal. Both I and Q inputs are dc-coupled with a ±500 mV differential full-scale range. The maximum modulation band- width is 230 MHz, which can be reduced by adding external capacitors to limit the noise bandwidth on the control lines.Both the RF inputs and outputs can be used differentially or single-ended and must be ac-coupled. The RF input and output impedances are nominally 50 over the operating frequency range. The DSOP pin allows the output stage to be disabled quickly in order to protect subsequent stages from overdrive.The AD8341 operates off supply voltages from 4.75 V to 5.25 V
while consuming approximately 125 mA.
key words: NOISE AND DISTORTION PERFORMANCE CHARACTERISTICS ESD CAUTION THEORY OF OPERATION
RF INPUT AND MATCHING I-Q ATTENUATORS
EVALUATION BOARD
