Date: 19/08/2011

Quad/dual channel DVGAs for higher-performance wideband radio systems

National Semiconductor Corp. has introduced a pair of LMH6522 quad- and LMH6521dual-channel, digital variable gain amplifiers (DVGA) that enable higher-performance wideband radio systems. They target applications such as 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 base stations.

Key Features of the LMH6522 Quad DVGA include:

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 include:
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

According to National Semiconductor, the major challenge for the radio designers is to produce the wider radio bandwidth with cost effective anti-alias filters (AAF), they are flexible to select from a range of impedance levels including low impedance levels such as 50-Ohms, which simplify the AAF design and improves performance and manufacturability. National's DVGAs are used 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 suited for driving high-speed ADCs, including National's ADC16DV160 dual 16-bit, 160 MSPS converter and LMH6521 is suited for driving National's ultra-high-speed ADC12D500/800RF 12-bit, 500 MSPS/800 MSPS direct RF-sampling ADCs.

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

For more information visit: www.national.com