Title :
Spectral analysis of multibit VCO-ADCs and PFM-ADCs with sinusoidal inputs
Author :
Gutierrez, Eric ; Hernandez, Luis
Author_Institution :
Electron. Technol. Dept., Carlos III Univ., Madrid, Spain
Abstract :
The analytical formulation of the output DFT of an oversampled converter based on a VCO has been recently disclosed for the single-bit case. However, most practical VCO-ADCs are constructed with a multibit configuration using a multiphase ring oscillator architecture. This paper shows that the spectral properties of a single-bit VCO-ADC are retained in the multibit case if an equivalent model is employed. This means that similar equations used to study the performance of single-bit ring oscillator can also be applied to the multibit case. Also, a multibit PFM-ADC has been proposed as an alternative to a conventional VCO-ADC, showing differences in the output spectrum respect to the VCO-ADCs based on ring oscillators. This paper describes these differences and how to apply the previous equations to study the PFM-ADC architecture.
Keywords :
analogue-digital conversion; discrete Fourier transforms; pulse frequency modulation; spectral analysis; voltage-controlled oscillators; PFM-ADC architecture; multibit PFM-ADC; multibit VCO-ADC; multibit configuration; multiphase ring oscillator architecture; output DFT; oversampled converter; single-bit VCO-ADC; single-bit ring oscillator; sinusoidal inputs; spectral analysis; spectral properties; Discrete Fourier transforms; Dynamic range; Frequency modulation; Mathematical model; Ring oscillators; Voltage-controlled oscillators; Data Conversion; Pulse Frequency Modulation; Sigma-Delta Modulation; Spectral Analysis;
Conference_Titel :
Circuits and Systems (ISCAS), 2015 IEEE International Symposium on
Conference_Location :
Lisbon
DOI :
10.1109/ISCAS.2015.7168869