A new temperature independent current controlled oscillator

This paper describes a circuit, which generates a low temperature-dependent bias currents. In this paper, low temperature coefficient reference is presented. The circuit is firstly employed to generate a current reference with temperature compensation, then, supply current to the current controlled ring oscillator (CCO). Because of the oscillation frequency of CCO is proportional to temperature, the current is designed to be inversely proportional to temperature to compensate the temperature variation of CCO. There are four different oscillation frequency with temperature compensation has been completed, they are 10MHz, 20MHz, 30MHz and 40MHz respectively. The proposed circuit has been design by a 0.18um CMOS technology process and using computer simulation to evaluate the thermal drift of the reference current. The temperature coefficient of the proposed CCO is 24 ppm/°C in the temperature range between -25 and 75°C at 10MHz. In the 20MHz, 30MHz and 40MHz oscillation frequency, the temperature coefficients are 32 ppm/°C, 38 ppm/°C and 34 ppm/°C respectively.