AlGaN/GaN　double　heterostructure　high　electron　mobility　transistor　(DH-HEMT＇s)　with　a　2.0　mu　m　gate　length　and　a　4　mu　m　channel　length　exhibiting　good　temperature　characteristics　has　been　demonstrated.　The　maximum　drain　current　I-ds　and　extrinsic　transconductance　G(m)　are　1300mA/mm　235mS/mm,　850mA/mm　174mS/mm　and　475mA/mm　95mS/rnm,　respectively　at　T　=　194　degrees　C,　20　degrees　C　and　400　degrees　C.　The　temperature　coefficient　of　I-ds　and　G　are　-1.4mA/degrees　C　and　-0.24mS/degrees　C　respectively.