Title :
Linearization of synthesizable VCO-based ADCs using delta modulation
Author :
Vishnu Unnikrishnan;Mark Vesterbacka
Author_Institution :
Division of Integrated Circuits and Systems, Dept. of Electrical Engineering, Linkö
Abstract :
VCO-based ADC is an attractive candidate for the synthesis of all-digital ADCs using standard cells. However, the non-linearity of a synthesizable VCO requires digital postprocessing to obtain good performance. We propose another solution where the input analog signal is pre-coded into a delta-modulated pulse stream which is used to drive a VCO-based converter. This causes the oscillator to operate at two distinct frequencies thereby eliminating the VCO non-linearity from the converter transfer function. A circuit is proposed that consists of a synthesized digital block realizing all the active parts of the circuit and a passive RC net used as an integrator. Spectre simulation of the netlist synthesized using a 65 nm standard cell library shows a performance of 8.2 bit ENOB over a 3 MHz bandwidth without using any digital post-processing.
Keywords :
"Frequency modulation","Standards","Voltage-controlled oscillators","Logic gates","Delta modulation"
Conference_Titel :
Circuit Theory and Design (ECCTD), 2015 European Conference on
DOI :
10.1109/ECCTD.2015.7300003