National Variable Gain Amplifier Released by National Semiconductor

Published:2011/8/30 3:47:00 Author:Li xiao na From:SeekIC

National Semiconductor was established in Danbury, Connecticut by Dr. Bernard J Rothlein on May 27, 1959. It is an American semiconductor manufacturer, specializing in analog devices and subsystems, headquartered in Santa Clara, California, USA. Power management circuits, display drivers, audio and operational amplifiers, communication interface products and data conversion solutions are the products of this company. The markets of National Semiconductor are in America or other countries, such as wireless handsets, displays and a variety of broad electronics markets and medical, automotive, industrial, and test and measurement application markets.

The digital variable gain amplifiers with a pair of quad- and dual-channel are released by National Semiconductor. The devices are especially designed for wideband radio systems. In the design of anti-alias filters (AAF) for wideband radio, a range of filter impedance levels is found by the designers. It includes low impedance levels such as 50ohm. It only not only simplifies the AAF design, but also improves performance and manufacturability. A range of load impedances are driven by DVGAs. A low-Z output drive is used to ensure signal fidelity and provide the additional power gain. The additional power gain is needed when it is driving low impedance filter.

The high -speed ADCs can be driven by LMH6522 and LMH6521, as well as the National’s ADC16DV160 dual 16-bit, 160 MSPS converter. National’s ADC12D500/800RF 12-bit and 500 MSPS/800 MSPS direct RF-sampling ADCs also can be driven by LMH6521. With the LMX2541 frequency synthesizer and one of National’s family of LMK04800 or LMK04000 clock jitter cleaners, a designer can make up a complete signal path. Intermediate frequency (IF) sampling receivers, I/Q digital pre-distortion (DPD) signal paths and wide-bandwidth direct-conversion radios are the applications of the gain amplifier, among which, the wide-bandwidth direct-conversion radios are used in multi-carrier GSM, TD-SCDMA, W-CDMA and LTE wireless basestations.


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