This paper addresses a mixed-mode CMOS circuit for Hyperdimensional Computing (HDC). HDC is based on the use of binary vectors with thousands dimensions to represent data in a holistic way. During the last years HDC has shown to be a powerful approach to solve classification problems. The proposed circuit architecture in this paper is made up of an array of 128 64 (8192) processing units (PUs) with a 1-bit ALU, local memory and connectivity to their 4 nearest neighbors to run the basic operations of HDC, i.e, binding, bundling and permutation. The architecture also includes a module to calculate Hamming distance to address classification. Post-layout simulations of the complete system working on various basic operations in 0.18 um CMOS technology are shown.