А VOLTAGE-CONTROLLED OSCILLATOR WITH А SMALL AREA AND A LARGE RANGE OF INPUT VOLTAGE AND OUTPUT FREQUENCY
A new method for designing a voltage-controlled oscillator (VCO) with a small area is presented. In comparison with other VCO circuits, the presented VCO has a smaller area, wider ranges of input voltage and output frequency. In comparison to VCO with a frequency-voltage converter (FVC) in feedback connection, the presented VCO has a smaller area by 32%, a wider input voltage range by 80%, a wider output frequency by 110%, and the linearity error of the output characteristics (output frequency and input voltage dependency) are higher by 2%. All parameters of VCO that are important for its applicability are used with their necessary values in the newly designed circuit. The most important parameter of VCO is the linearity of the output characteristics. A little disadvantage of the newly designed VCO is the linearity error of the output characteristics, which is 2.015%, but it is very small, and the output frequency is almost directly proportional to the input voltage (subtracting the initial value of the output frequency). In many schemes, a big part of the area is taken by the operational amplifier (OpAmp), as the sizes of its transistors are very big. For having a small area, other blocks of VCO are designed with relatively small transistor sizes. One of the advantages of the new VCO is that by designing the same scheme for other technologies, the circuit can be designed for the needed input voltage values, and the output frequency values can be secured in the maximum range, because the principle of its work is based on some blocks whose output signals depend on the input signals by formulas.