Multi-GHz A/D converter using resonant-tunnelling multiple-valued logic circuits

Resonant-tunneling diodes (RTDs) exhibit faster switching times (1.5 ps) than any other semiconductor devices. Their negative differential resistance characteristics provide opportunities to implement functions, such as multiple-valued logic, with reduced circuit complexity. Experimental results for a 10 GHz resonant-tunneling 3-valued quantizer and a 4 b flash A/D converter employing such quantizers are presented. The number of active devices is reduced to 240, 1/4 the number required in conventional A/D converters. Maximum sampling frequencies of 10GHz are predicted.