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LT5546 - 40MHz to 500MHz VGA and I/Q Demodulator with 17MHz Baseband Bandwidth

The LT5546 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 down-conversion to I and Q baseband signals with a single supply voltage of 1.8V to 5.25V. The VGA gain has a linear-in-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.

Features 17MHz I/Q Lowpass Output Noise Filters Wide Range 1.8V to 5.25V Supply Voltage Frequency Range: 40MHz to 500MHz THD < 0.14% (-57dBc) at 800mVP-P Differential Output Level IF Overload Detector Log Linear Gain Control Range: -7dB to 56dB Baseband I/Q Amplitude Imbalance: 0.2dB Baseband I/Q Phase Imbalance: 0.6° 7.8dB Noise Figure at Max Gain Input IP3 at Low Gain: -1dBm Low Supply Current: 24mA Low Delay Shift Over Gain Control Range: 2ps/dB Outputs Biased Up While in Standby 16-Lead QFN 4mm × 4mm Package with Exposed Pad Typical Application

Applications GPS IF Receivers Satellite IF Receivers VHF/UHF Receivers Wireless Local Loop Packaging

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