CMOS OTA - C High - Frequency Sinusoidal Oscillators

Several topology families are given to implement practical CMOS sinusoidal oscillators by using operational transconductance amplifier-capacitor (OTA-C) techniques. Design techniques are proposed taking into account the CMOS OTA’S dominant nonidealities. Building blocks are presented for amplitude control, both by AGC schemes and by limitation schemes. Experimental results from 3and 2-pm CMOS (MOSIS) prototypes showing oscillation frequencies up to 69 MHz are obtained. The amplitudes can be adjusted between 1 V peak to peak and 100 mV peak to peak. Total harmonic distortions from 2.8% down to 0.2% have been experimentally measured in the laborato~.