A 1.0-8.3 GHz Cochlea-Based Real-Time Spectrum Analyzer With Δ-Σ-Modulated Digital Outputs

The biological inner ear, or cochlea, is a sophisticated signal processing system that performs spectrum analysis over an ultra-broadband frequency range of ~20 Hz to 20 kHz with exquisite sensitivity and high energy efficiency. Electronic cochlear models, which mimic the exponentially-tapered structure of the biological inner ear using bidirectional transmission lines or filter cascades, act as fast and hardware-efficient spectrum analyzers at both audio and radio frequencies. This paper describes a cochlea-based digitally-programmable single-chip radio frequency (RF) spectrum analyzer in 65 nm CMOS. This “RF cochlea” chip includes a transmission-line active cochlear model with 50 parallel exponentially-spaced stages that analyzes the radio spectrum from 1.0-8.3 GHz. The outputs of all stages are encoded in parallel as delta-sigma ( $\Delta - \Sigma $ ) modulated digital signals for real-time demodulation and analysis by a digital back-end processor. The chip consumes 418 mW and typically generates ~1 GS/s of total data at an ENOB of 5–6 bits. An artificial intelligence (AI)-driven single-channel cognitive radio (CR) receiver based on the RF cochlea has also been implemented and tested.