IF Quadrature Demodulator works in portable applications.
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Press Release Summary:
Model LT5546 monolithic IF (Intermediate Frequency) quadrature demodulator operates with one supply voltage as low as 1.8 V and accepts IF input signal from 40-500 MHz. It incorporates precision quadrature phase-shifter for accurate I/Q demodulation and low-distortion VGA with log-linear gain control range from -7 to +56 dB. Offered in 4 x 4 mm, 16-lead plastic QFN surface mount package, unit includes on-chip signal power detector with -30 to +8 dBm range.
Original Press Release:
Low Voltage IF Quadrature Demodulator for High Performance Portable Applications
MILPITAS, CA - December 10, 2003 - A monolithic, high performance IF quadrature demodulator from Linear Technology Corporation operates with a single supply voltage as low as 1.8V, making it ideal for portable applications. The LT5546 has applications in GPS receivers, wireless local loop, satellite IF receivers, and mobile wireless data receivers. The device accepts an IF (Intermediate Frequency) input signal from 40MHz to 500MHz. It incorporates a precision quadrature phase-shifter for accurate I/Q demodulation and a low distortion variable gain amplifier (VGA) with a log-linear gain control range from -7dB to 56dB.
The demodulated I/Q baseband signals pass through on-chip 17MHz low-pass noise reduction filters in the LT5546, reducing the need for external filtering. The I/Q outputs are buffered by low distortion, high linearity amplifiers. When signals are momentarily too high due to excessive VGA gain, the device's output amplifiers limit symmetrically, assuring rapid recovery from signal overload after the VGA gain is adjusted. Moreover, the LT5546 includes an on-chip signal power detector with a detection range of -30dBm to +8dBm to assist in high signal level detection and corresponding gain adjustment.
The LTC5546 is offered in a 4mm x 4mm 16-lead plastic QFN surface mount package, for a small PC board footprint. Pricing starts at $3.35 each in 1,000-piece quantities.
Summary of Features: LTC5546
Input Frequency from 40MHz to 500MHz
Low Supply Voltage Operation to 1.8V with Low Power Consumption
Built-in log-linear variable gain range: -7dB to 56dB
Low Distortion: THD < 0.14% (-57dBc)
I/Q Amplitude Imbalance: 0.2dB
I/Q Phase Imbalance: 0.6º
On-Chip, Large Signal IF Power Detector
Company Background
Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include operational, instrumentation and audio amplifiers; voltage regulators, power management devices, DC-DC converters and voltage references; comparators; monolithic filters; communications interface circuits; one-chip data acquisition sub-systems; pulse-width modulators and sample-and-hold devices; and high frequency devices. Applications for Linear Technology's high performance circuits include wireless and broadband telecommunications infrastructure, cellular telephones, networking products and satellite systems, notebook and desk top computers, computer peripherals, video/multimedia, industrial and medical instrumentation, automotive electronics, factory automation, process control, military and space systems, and high-end consumer products including digital cameras, MP3 players and other electronic products.
Note: LT, AND LTC are registered trademarks of Linear Technology Corp.
