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800MHz to 2.7GHz Direct Conversion I/Q Demodulator Offers High Performance for 3G, WiMAX Basestations & RFID Readers
MILPITAS, CA - February 19, 2007 - A new high linearity direct
conversion I/Q demodulator from Linear Technology significantly
reduces the cost of 3G and WiMAX basestation receivers. The
LT5575's extended operating frequency range from 800MHz to 2.7GHz
covers all of the cellular and 3G infrastructure, WiMAX and RFID
bands with a single part. Its capability to convert from RF
directly to baseband at DC or low frequency results in simplified
receiver designs, reduced component count and use of lower cost,
low frequency components. The LT5575 offers an outstanding IIP3 of
28dBm and IIP2 of 54.1dBm at 900MHz, and an IIP3 of 22.6dBm and
IIP2 of 60dBm at 1.9GHz. Moreover, the device has a conversion gain
of 3dB, which when combined with a DSB Noise Figure of 12.7dB
produces excellent receiver dynamic range. 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,
providing an unprecedented level of demodulation accuracy.

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The LT5575 is capable of supporting multiband basestations
covering both the 850MHz GSM/EDGE bands and the 1.9GHz/2.1GHz 3G
wireless services (including CDMA2000, WCDMA, UMTS, and TD-SCDMA).
It is ideal for single carrier micro- and pico-basestations, where
low cost architectures are key. The LT5575's performance is also
well suited for 2.6GHz 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
900MHz makes it an exceptional 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 490MHz. Both the RF and the LO
inputs have integrated on-chip transformers that enable 50Ohm
broadband matching and single-ended operation. This simplifies the
design and reduces costs. |
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. Pricing starts at $7.75 each in 1,000 piece
quantities. The product is available immediately from stock.
| Summary of Features: LT5575 |
| • |
Frequency Range |
800MHz to 2700MHz
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| • |
IIP3 @ 900MHz
@ 1900MHz
@ 2500MHz |
+28 dBm
+22.6 dBm
+23.3 dBm
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| • |
IIP2 @ 900MHz
@ 1900MHz
@ 2500MHz |
+54.1dBm
+60 dBm
+52.3 dBm
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| • |
Noise Figure @ 1900MHz |
12.7 dB
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| • |
I & Q Amplitude Mismatch |
0.04 dB
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| • |
I & Q Phase Mismatch |
0.6 degree
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Broadband High Performance Direct Conversion I/Q
Demodulator
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