Datasheet Linear Technology LT5546 — Datenblatt

LT5546
40MHz to 500MHz VGA
and I/Q Demodulator with
17MHz Baseband Bandwidth U FEATURES DESCRIPTIO в–  The LTВ®5546 is a 40MHz to 500MHz monolithic integrated
quadrature demodulator with variable gain amplifier (VGA)
and 17MHz I/Q baseband bandwidth designed for low voltage operation. It supports standards that use a linear modulation format. The chip consists of a VGA, quadrature downconverting mixers and 17MHz lowpass noise filters (LPF).
The LO port consists of a divide-by-two stage and LO
buffers. The IC provides all building blocks for IF downconversion to I and Q baseband signals with a single
supply voltage of 1.8V to 5.25V. The VGA gain has a linearin-dB relationship to the control input voltage. Hard-clipping amplifiers at the mixer outputs reduce the recovery
time from a signal overload condition. The lowpass filters
reduce the out-of-band noise and spurious frequency
components. The –3dB corner frequency of the noise
filters is approximately 17MHz and has a first order rolloff. The standby mode provides reduced supply current
and fast transient response into the normal operating mode
when the I/Q outputs are AC-coupled to a baseband chip. в– 
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