Localization (a.k.a. locationing) is a central concern for ubiquitous self-configuring sensor networks. In this paper the implementation of a distributed, least-squares-based localization algorithm is presented. Low power and energy dissipation are key requirements for sensor networks. As part of the sensor network, the localization system must also conform to these requirements. An ultra-low-power and dedicated hardware implementation of the localization system is therefore presented. The cost of fixed-point implementation is also investigated. The design is implemented in a 0.13 µ CMOS process. It dissipates 1.7mW of active power and 0.122J/op of active energy with a silicon area of 0.55mm². The mean calculated location error due to fixed-point implementation is shown to be 6%.