A low power voltage source is generated by altering the device size in existing topology has been presented. Bandgap voltage reference is generated by combination of start-up, supply independent, operational amplifier (Op-amp) and bandgap core circuits which has been designed such that low sensitivity of temperature and supply variation. It has been designed with minimum supply of 0.8 V without use of low threshold device, and the maximum supply current is 35A. It has been implemented in 180 nm standard digital CMOS Process. The circuit generates a reference voltage of 540 mV and has a temperature coefficient of 14 ppm from −40C to 120C. The generated reference voltage is independent of temperature and supply variations have been mathematically proved by analyzing the circuit design. Also, proper selection of on-chip passive components and its values has been chosen which is based on low noise. Comparing the pre and post layout simulation results has been presented.