Product category: Analogue and Mixed Signal ICs
News Release from: Linear Technology Corp | Subject: LT5517
Edited by the Electronicstalk Editorial Team on 20 December 2004
Demodulator stands up to direct
conversion tasks
A new, very high linearity and low noise I/Q demodulator provides the performance needed for direct conversion and IF conversion of radio signals to baseband for high performance receivers.
A new, very high linearity and low noise I/Q demodulator from Linear Technology provides the performance needed for direct conversion and IF conversion of radio signals to baseband for high performance receivers The LT5517 has an IIP3 (input third-order intercept point) of 23.5dBm and a noise figure of 9.5dB at 200MHz, allowing the robust detection of weak signals, even in the presence of high level interference
This article was originally published on Electronicstalk on 28 Jul 2004 at 8.00am (UK)
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The LT5517 integrates a precision 0 and 90-degree phase splitter, providing accurate I (in-phase) and Q (quadrature-phase) demodulation of RF signals, ranging from 40 to 900MHz, directly to baseband in a compact solution.
The LT5517 is well suited for IF and RF demodulators in high performance, wireless infrastructure receiver applications.
Other applications include micro-basestations, repeater cells, RFID readers, and broadband fixed wireless access.
The LT5517 offers a high level of integration, incorporating a pair of matched high linearity mixers, with an on-chip quadrature phase generator and splitter.
The I and Q signal paths are internally gain matched to 0.03dB typical, with a typical phase mismatch of 0.7 degree, resulting in highly accurate I and Q demodulation.
The differential I and Q outputs have low DC offset, typically 0.5mV, and built-in 130MHz lowpass filters to remove out-of-band noise.
The LT5517 provides a compact and robust receiver solution.
The internal quadrature phase splitter uses a local oscillator (LO) derived from a divide-by-two circuit.
Correspondingly, the 2XLO input port accepts a signal at twice the LO frequency, thus minimising LO leakage to the RF port.
Moreover, the LT5517 has excellent port-to-port RF leakage, reducing external RF filtering requirements.
The 2XLO input requires only a -5dBm drive level, and is internally matched to 50ohm, thus providing a simple, single-ended interface.
LT5517 operates from a single 4.5 to 5.25V supply, drawing a power supply current of 90mA.
An Enable pin allows the device to power down, drawing a typical off-state current of 0.1uA.
Turn-on and turn-off time is typically under 300ns.
The device is offered in a 16-lead 4 x 4mm surface mount QFN package.
Priced at $7.40 each in 1000-piece quantities, the product is available from stock. Request a free brochure from Linear Technology Corp ...
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