The development of low power integrated system is expected to lead to the expansion of next-generation power-efficient applications. A voltage-reference is widely used in integrated circuits to generate an on-chip reference voltage. The generated voltage-reference is used for building blocks like analog-to-digital converter (ADC) and digital-to-analog converter (DAC). Because voltage reference is an important building block of analog design, development of low power voltage reference circuits requires special attention. This thesis presents a new circuit topology to produce a single ended output proportional to absolute temperature (PTAT) voltage for building a voltage-reference circuit. PTAT voltage is generated by two diode-connected MOSFETs in the subthreshold region. Complementary to absolute temperature (CTAT) voltage is realized, which has negative temperature coefficient (TC), by the gate-source voltage of a MOSFET in the subthreshold region. This design has low power dissipation and simple circuit. With a supply voltage of 1.1V, this circuit designed and fabricated in 0.18μm CMOS technology dissipates 2.2μW. Similar circuit topology can also be used to design a nano-ampere one quadrant analog multiplier with high tolerance to process and temperature variations