A family of ADCs is, claims National Semiconductor, the first in the industry to directly sample RF signals beyond 2.7GHz, with IMD3 (third-order intermodulation distortion) up to -71dBc. The 12bit ADCs in the ADC12Dxx00RF series eliminate up to 20 components by eliminating multiple intermediate frequency down-conversion stages, such as amplifiers, mixers and filters. They sample into, and beyond, the seventh Nyquist zone, delivering the high input bandwidth and the low noise at high frequencies to enable RF sampling for radar and other military applications. They can reduce board size and weight in 3G and 4G wireless basestations as well as microwave backhaul and wideband software-defined radios. The ADC12D1800RF provides interleaved single-channel sampling rates up to 3.6Gsample/s (or dual-channel rates up to 1.8Gsample/s), with IMD3 of -64dBc at 2.7GHz. The ADC12D1600RF provides single-channel rates up to 3.2Gsample/s, with IMD3 of -70dBc at 2.7GHz. The ADC12D1000RF samples at up to 2Gsample/s, with IMD3 of -69dBc at 2.7GHz. Sampling rates of up to 1.6Gsample/s are provided with ADC12D800RF, with IMD3 of -71dBc at 2.7GHz. The fifth device, the ADC12D500RF provides interleaved single-channel sampling rates up to 1Gsample/s with IMD3 of -69dBc at 2.7GHz.
