National Semiconductor has introduced a pair of LMH6522 quad- and LMH6521 dual-channel DVGAs (digital variable gain amplifiers) for multi-channel wideband radio systems. The amplifiers are suitable for IF sampling receivers, I/Q DPD (digital pre-distortion) signal paths and wide-bandwidth direct-conversion radios used in multi-carrier GSM, TD-SCDMA (time division-synchronous code division multiple access), W-CDMA and LTE wireless basestations. The amplifiers are suitable for driving high-speed ADCs, including the company's ADC16DV160 dual 16bit, 160Msamples/s version. The dual-channel amplifier is suitable for driving the company's ADC12D500/800RF 12bit, 500/800Msamples/s direct RF sampling ADCs. A signal path can be formed by adding the LMX2541 frequency synthesiser and the company's LMK04800 or LMK04000 clock jitter cleaners. The quad-channel amplifier has OIP3 (output intercept point) of 49dBm at 200MHz frequency, and provides 1 to 31dB gain step range. It also provides noise figure of 8.5dB at maximum gain and is available in a 54pin LLP (leadless leadframe package). The dual-channel amplifier has OIP3 of 48.5dBm at 200MHz input frequency, and features channel gain or phase matching of ±0.04dB or ±0.45°. It provides 0.5 to 31.5dB gain step range and noise figure of 7.3dB at maximum gain. It is available in a 32pin LLP package.
