DVGAs from National Semiconductor Enable Higher-Performance Basestation Radio Architectures

12th August 2011
Posted By : ES Admin
Dual/Quad DVGAs Combine High Channel Count and Excellent High Frequency Linearity
National Semiconductor Corp. today introduced a pair of quad- and dual-channel, digital variable gain amplifiers (DVGA) that enable higher-performance wideband radio systems. The LMH6522 quad and LMH6521 dual DVGAs provide superior linearity performance over a wide frequency range, making them an ideal solution for the most challenging multi-channel wideband wireless systems. Target applications include intermediate frequency (IF) sampling receivers, I/Q digital pre-distortion (DPD) signal paths and wide-bandwidth direct-conversion radios used in multi-carrier GSM, TD-SCDMA, W-CDMA and LTE wireless basestations.

Radio designers face the challenge of producing cost effective anti-alias filters (AAF) that meet the demanding requirements of today’s wider radio bandwidths. The flexibility to select from a range of filter impedance levels, including low impedance levels such as 50-Ohms, not only simplifies the AAF design, but also improves performance and manufacturability. National’s DVGAs are optimized for driving a wide range of load impedances. Their low-Z output drive delivers exceptional signal fidelity and provides the additional power gain needed when driving low impedance filters.

The LMH6522 and LMH6521 are well-suited for driving high-speed ADCs, including National’s ADC16DV160 dual 16-bit, 160 MSPS converter. In addition, the LMH6521 is ideal for driving National’s ultra-high-speed ADC12D500/800RF 12-bit, 500 MSPS/800 MSPS direct RF-sampling ADCs. By adding the LMX2541 frequency synthesizer and one of National’s family of LMK04800 or LMK04000 clock jitter cleaners, a designer can form a complete signal path.

Key Features of the LMH6522 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 LMH6521 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

Pricing and Availability
Available now, the LMH6522 is priced at $9.85 and the LMH6521 is $6.15, both in 1,000-unit quantities.

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