A VCO-based phase-expanding conversion designed for time-domain data converters
This paper presents the design of a VCO-based phase-expanding converter (PEC) that converts a time residue to improve time resolution for the time-domain data converters. A voltage controlled oscillator, which has multiphase structure, is combined with the multi-layer delay chain to generate quadruple phases, and thus expands the overall resolution. Since the architecture of this converter is flexible for different designs, we propose a 6-bit, 250MHz PEC using a 16-phase, 1GHz VCO with quadruple phase expander in this paper. Simulations in a 0.18?m the CMOS process indicate that the PEC has DNL less than 0.2LSB LSB, and INL less than 0.3LSB. Furthermore, with the frequency variation from 0.9GHz to 1.1GHz, the PEC still has DNL 0.21LSB, and INL 0.29LSB. Experiment results show that the DNL is 0.520.13LSB and the INL is 0.210.66LSB.
vco-based time-domain data converter phase-expanding converter (pec) multiphase voltage-controlled oscillator (vco) encoder