We　demonstrate　a　semi-analytical　parameter　extraction　method　to　characterize　high-speed　and　high-photocurrent　InP-based　unitraveling-　carrier　photodiodes　with　dipole-doped　structure.　The　accuracy　of　proposed　method　has　been　validated　with　good　agreements　between　the　measured　and　simulated　results　of　reflection　coefficients　and　frequency　responses　in　a　wide　frequency　range　up　to　40　GHz.　(C)　2016　Wiley　Periodicals,　Inc.