Wireless sensor networks are used in variety of applications including environmental monitoring, industrial control, healthcare, home automation, traffic control, and temperature and pressure monitoring systems. Many one-time use wireless micro sensor applications require ultra-low-power devices due to the limited energy capacity and lifetime of their small-size battery. Many sensor nodes require an analog-to-digital converter (ADC) to convert the analog output of the sensor to digital for storage and/or further processing. In this work, an 8-bit ultra-low-power successive approximation register (SAR) ADC is presented that operates from a low power supply voltage of 1V. The circuit is implemented in a 0.18 μm bulk CMOS technology without using any 10W-VT devices. In terms of active components, this ADC requires one comparator, 18 D flip-flops, several switches, and one voltage doubler. The ADC achieves an effective number of bits of 7, while operating with a sampling rate of 100kS/s and consuming 1.4 μW from a 1 V supply.