In this paper, a nonlinear analysis of cross- coupled super-regenerative oscillators (SROs) is presented. The start-up and decay envelopes of the oscillator output are studied in relation to the input. The SRO start-up time and the maximal achievable quenching frequency are investigated. For phase modulation purposes, the relation between the initial phases of the input and output signals is investigated. In addition, a frequency-domain analysis is performed to ease the characterization of circuit prototypes at frequencies where time-domain measurements are not possible. The analytical results are verified by circuit-level simulations and measurements of a 2.4-GHz SRO. This study provides design guidelines for the design of SROs in cross-coupled architectures and helps in determining the optimal system parameters when targeting both amplitude and phase modulations. To the authors' best knowledge, this is the first study investigating analytically the phase relation between the SRO input and output signals and the nonlinear large-signal behavior of SROs.