Title :
Linear current-controlled oscillator for analog to digital conversion
Author :
Raghunandan, K.R. ; Viswanathan, T. Lakshmi ; Viswanathan, T.R.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of Texas at Austin, Austin, TX, USA
Abstract :
Current-controlled oscillators (CCO) for analog to digital conversion need linear tuning-characteristics. A new CCO design in which the period of oscillation is defined by charging the timing capacitor to a reference voltage by the input current, is described. The sources of non-linearity in the tuning characteristics are identified and modeled. A method of compensating for these errors is presented. Process and temperature effects are minimized by trading speed for robustness in manufacturing. The design has been verified by simulations as well as fabricating a prototype in a typical 0.18μm process node. Simulation results indicate that 0.2% linearity can be obtained from 0-100 deg C for the frequency range upto 500MHz. The main idea is to improve linearity by design as much as possible before performing calibration.
Keywords :
analogue-digital conversion; circuit tuning; error compensation; oscillators; CCO; analog-digital conversion; error compensation method; linear current-controlled oscillator; linear tuning-characteristic; nonlinearity source; process effect; prototype fabrication; reference voltage; size 0.18 mum; temperature effect; timing capacitor charging; trading speed; Capacitors; Delays; Mirrors; Oscillators; Switches; Transistors; Tuning;
Conference_Titel :
Custom Integrated Circuits Conference (CICC), 2014 IEEE Proceedings of the
Conference_Location :
San Jose, CA
DOI :
10.1109/CICC.2014.6946121
