A circuit for implementing a polar decoder is described. The circuit includes a log-likelihood ratio processing circuit. A path metric update circuit is coupled to receive log-likelihood values for decoded bits from the log-likelihood ratio processing circuit, wherein the path metric circuit generates path metric values for the decoded bits. A partial sum calculation circuit is coupled to receive the path metrics; and a sort and cull circuit is coupled to receive a list of child path, wherein the sort and cull circuit eliminates invalid paths from the list of child paths. A method of implementing a polar decoder is also described.