Question

In which technique RF is amplified until it is hard-limited into a square wave?

(a) Super heterodyne receiver

(b) One-bit direct conversion digital receiver

(c) Two-bit direct conversion digital receiver

(d) Phase crossing counter receiver

This question was addressed to me during an interview.

The origin of the question is RF and IF Processing Tradeoffs in section Technology Tradeoffs in Software Defined Radio of Cognitive Radio

Answer 1

The correct option is (b) One-bit direct conversion digital receiver

For explanation I would say: One-bit direct conversion digital receiver amplifies RF until it is hard limited into a square wave. An advantage of this architecture is that the channel states are stored in lookup tables.