12-bit 3.6Gsps ADC idea for software defined radios

National Semiconductor’s new ADC12D1800 ADC (analog to digital converter) finds application in software defined radio signal chains as well as radar, high-speed instrumentation, and data acquisition systems. The ADC12D1800 provides sampling rates up to 3.6 GSPS, or dual-channel rates up to 1.8 GSPS. With a 125MHz input signal, the part gives 57.8 dB SNR (signal to noise ratio), 67 dBc SFDR (spurious free dynamic range) and 9.2 ENOB (effective number of bits). The part offers dynamic performance of -147 dBm/Hz noise floor, 52 dB noise power ratio (NPR) and -61 dB full-scale intermodulation distortion (IMD). Te part runs off a 1.9V single supply. The IC consumes 2.05W per channel. It includes circuitry for multi-chip synchronization, programmable gain and offset adjustment per channel. The internal track-and-hold amplifier and extended self-calibration scheme enable a flat response of all dynamic parameters for input frequencies exceeding 2 GHz, while providing an 10^-18 code error rate.

A single ADC12D1X00 combined with a variable gain amplifier can replace multiple mixers, filters, amplifiers and local oscillator stages used in traditional heterodyne double- or triple-conversion radio implementations.

The parts operate over a -40 to +85°C range and come in a 292-ball, thermally enhanced BGA package. Contact National Semiconductor for pricing. Small quantities are immediately available, and large production orders have six-week leadtimes.