Direct Conversion Modulator Boosts Basestation Performance

The LT5528 is a direct I-Q modulator incorporating a matched pair of double-balanced mixers that form a carrier suppressed, image reject I-Q (In phase and quadrature) modulator. It is intended for base station transmitters in the wireless infrastructure such as W-CDMA, TD-SCDMA, GSM and PHS. The I and Q inputs accept complex modulation signals from the baseband circuitry and upconvert them directly to RF signals (1.5 to 2.5 GHz) using a local oscillator operating at the same frequency. Output third-order intercept (OIP3) is specified at 20.5 dBm at 2.14 GHz. Noise floor is –159 dBm/Hz and ACPR (adjacent channel power ratio) is –66 dBc. The device operates from a single 5V supply and comes in a 4 mm x 4mm, 16-pin, surface-mount QFP. Price is $5.95 each/1,000. LINEAR TECHNOLOGY CORP., Milpitas, CA. (408) 432-1900.