Abstarct: Supplying different voltage levels that are stable against temperature changes, manufacturing processes and the main power supply of the circuit are key factors for the proper operation of electronic circuits. Such voltage is referred to the reference voltage, and because the primary voltage reference circuits were capable of generating a voltage within the silicon bandgap voltage range, these circuits were known as the bandgap reference. There are many structures in the field of voltage reference generation. With the developing of technology and lower occupied area on the chip, power supplies also become smaller and the need for sub_1V voltage references increases, so common structures that generate a constant bandgap voltage over one volt will lose their functionality. Also, the offset of operational amplifier is a source of error in bandgap circuits, especially in sub_1 volt references. In this thesis, two switch-capacitor voltage references have been designed in which, unlike conventional structures, no resistor is used, and the structure of the circuits is baxsed on the generation of PTAT and CTAT voltages using a BJT and the storage of voltages on the capacitors by the switching scheme. Eliminating the resistors from these two structures increases the accuracy of the generated voltage and use of only one BJT, in contrast to the conventional structures which use two BJTs, eliminates the mismatch effect of two bipolar transistors. The first proposed voltage reference structure has the ability to adjust the output voltage to the desired levels, but needs two positive and negative power supplies for proper operation. By modifying the first proposed circuit structure, the second switch-capacitor voltage reference was designed in such a way that, in addition to the ability to generate adjustable sub_1V reference voltage levels, it also has the ability of offset cancelation. The second proposed circuit structure generates the requirement for the production of adjustable reference voltages and eliminates the effect of the offset of operational amplifier only by using new switching scheme on four capacitors. The first two capacitors produce a temperature insensitive reference voltage and the next two capacitors provide a degree of freedom to generate adjustable sub_1 voltages. In this thesis, after presenting the proposed circuit, the reference voltage equations made according to the circuit parameters and the condition of the generated voltage independent temperature has been calculated. With respect to the calculated equations, the proposed output reference voltage is dependent on the ratio of capacitors in the circuit, which is an advantage, because the capacitor ratio in integrated circuits can be made with high precision, which means the accuracy of proposed reference voltage and reducing its sensitivity to the manufacturing errors. Finally, the proposed circuit was designed in the TSMC 0.18μm CMOS technology and simulated with ADS software. In a case study, simulations show that the proposed voltage reference is capable of generating a reference voltage of 460 mV with a temperature coefficient of 24.4 at a temperature range of -40 to 85 degrees Celsius. Also, Monte Carlo simulations for 200 iterations and 1% mismatch of the devices indicate that the average reference voltage ( ) is 0.467 V and its standard deviation( ) is 0.0047 V. Simulations also indicate that the proposed structure significantly eliminate the effect of the operational amplifier offset in the output of reference voltage circuit.