National Semiconductor LMH6522/LMH6521 digital variable gain amplifier range

National Semiconductor has introduced a pair of quad- and dual-channel, digital variable gain amplifiers that enable higher-performance wideband radio systems.

The LMH6522 quad and LMH6521 dual DVGAs provide good linearity over a wide frequency range, making them suitable for multichannel wideband wireless systems.

Target applications include intermediate frequency sampling receivers, I/Q digital pre-distortion signal paths and wide-bandwidth direct-conversion radios used in multicarrier GSM, TD-SCDMA, W-CDMA and LTE wireless base stations.

The devices are optimised for driving a wide range of load impedances. Their low-Z output drive delivers good signal fidelity and provides the additional power gain needed when driving low impedance filters.

They are suitable for driving high-speed ADCs, including the company’s ADC16DV160 dual 16-bit, 160 MSPS converter. The LMH6521 can be used for driving the ultra-high-speed ADC12D500/800RF 12-bit, 500 MSPS/800 MSPS direct RF-sampling ADCs.

Key features of the quad DVGA: OIP3 - 49 dBm at 200 MHz input frequency; precise 1 dB gain steps over a wide 31 dB range; noise figure of 8.5 dB at maximum gain; supplied in a 54-pin LLP package.

Key features of the dual DVGA: OIP3 - 48.5 dBm at 200 MHz input frequency; channel gain/phase matching of ±0.04 dB/±0.45 deg; precise 0.5 dB gain steps over a wide 31.5 dB range; noise figure of 7.3 dB at maximum gain; supplied in a 32-pin LLP package.