Product category:
Communications ICs (Wireless)
News Release from: Linear Technology Corp | Subject: LT5568
Edited by the Electronicstalk Editorial
Team on 23 January 2006
Quadrature modulator cuts basestation
costs
A new high performance quadrature modulator is optimised for 850 to 965MHz GSM, cdma2000, ISM and RFID modulator applications.
A new high performance quadrature modulator from Linear Technology is optimised for 850 to 965MHz GSM, cdma2000, ISM and RFID modulator applications The LT5568 accepts I (in phase) and Q (quadrature phase) baseband signals and modulates directly to the RF transmission frequency
This article was originally published on Electronicstalk on 28 Jul 2004 at 8.00am (UK)
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The product features exceptional linearity with an OIP3 (output 3rd order intercept point) of 22.9dBm and an OIP2 (output 2nd order intercept point) of 63dBm at 850MHz.
The LT5568's noise floor is -160.3dBm/Hz, and its image rejection is -46dBc with an LO leakage of -43dBm.
This device meets or exceeds the dynamic range requirements of GSM cellular basestations as well as other high performance wireless infrastructure transmitters.
The LT5568 is a highly integrated chip comprising two matched, high linearity mixers, a precision 0 and 90-degree phase shifter, a 50ohm LO input buffer, 50ohm I and Q inputs, and an on-chip RF transformer with an output matched to 50ohm within the band of 700 to 1050MHz.
The RF transformer sums the modulated signals from the I and the Q channel mixers' outputs, and converts the differential signal to that of a single-ended output.
The LO input is also single-ended, thus easing the design task.
The two on-chip mixers are well balanced, producing exceptional LO leakage performance.
At LO input power of 0dBm, leakage to the RF output at 850MHz is an exceptional -43dBm, uncalibrated.
Similarly, the on-chip precision phase shifter is accurate to better than 0.5 degree mismatch, enabling an uncalibrated image rejection performance of -46dBc.
The LT5568 operates from a single 5V supply voltage.
Typical operating current is 117mA.
The device can be shut down by an enable pin.
When disabled, the chip draws 50uA maximum quiescent current to conserve power.
For half-duplexing or time-division multiplexed operating modes, the chip can be switched on and off rapidly using the enable pin.
The LT5568 is offered in a 16-pin 4 x 4mm surface mount QFN package.
Pricing starts at $5.35 in 1000-piece quantities, and the device is available from stock. Request a free brochure from Linear Technology Corp ...
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