Super-regeneration-inspired time-based testing of LC-tank oscillators

This paper examines a new architecture that combines super regeneration and time-based signal processing concepts to implement frequency-to-time conversion. The proposed structure can also be used to perform LC-tank oscillators testing by using simple and low-resolution digital circuits. Its front-end consists of two cross-coupled oscillators, triggered in time by two step-like signals with a time separation that is externally controlled. The time separation, together with the cross coupling arrangement, results in a controlled start-up time of oscillation from which the frequency of oscillation can be deduced. The start-up time, extracted using envelope detection and coarse time digitization circuits, is then non-destructively measured. A proof-of-concept circuit is designed and laid out in a standard 90-nm CMOS process. Post-layout simulations confirm the feasibility of the proposed approach.