Linear Announces 800 MHz To 2.7 GHz Direct Conversion I/Q Demodulator

Milipitas, CA -- Linear Technology has launched a new high linearity direct conversion I/Q demodulator for 3G and WiMAX basestation receivers. The LT5575's extended operating frequency range from 800 MHz to 2.7 GHz covers all of the cellular and 3G infrastructure, WiMAX and RFID bands with a single part. Its capable of converting from RF directly to baseband at DC or low frequency. The LT5575 offers an IIP3 of 28 dBm and IIP2 of 54.1 dBm at 900 MHz, and an IIP3 of 22.6 dBm and IIP2 of 60 dBm at 1.9 GHz. Moreover, the device has a conversion gain of 3 dB. The device's I (In-phase) and Q (Quadrature phase) outputs have typical amplitude and phase matching of 0.04dB and 0.6 degree, respectively.

The LT5575 is capable of supporting multiband basestations covering both the 850 MHz GSM/EDGE bands and the 1.9 GHz/2.1 GHz 3G wireless services (including CDMA2000, WCDMA, UMTS, and TD-SCDMA). It is suitable for single carrier micro- and pico-basestations. The LT5575's performance is also suited for 2.6 GHz WiMAX basestations, and as an IF demodulator in a microwave radio link or satellite receiver. Additionally, the LT5575's high 13.2dBm P1dB (1dB compression point) performance at 900 MHz makes it a demodulator for high performance RFID readers.

The LT5575 integrates two matched, high linearity mixers. These are driven in quadrature by a low-noise, buffered LO (Local Oscillator) with an on-chip precision 0° and 90° phase shifter. The mixers produce accurate I and Q demodulated outputs capable of supporting a baseband bandwidth from DC up to 490 MHz. Both the RF and the LO inputs have integrated on-chip transformers that enable 50Ohm broadband matching and single-ended operation.

The LT5575 operates from a single 5V supply, drawing a quiescent supply current of 132mA. The device comes in a 16-lead 4mm x 4mm QFN package.

SOURCE: Linear Technology Corporation