Monolithic integration of multiple compound semiconductor FET devices
Various aspects of the technology provide a dual semiconductor power and/or switching FET device to replace two or more discrete FET devices. Portions of the current may be distributed in parallel to sections of the source and drain fingers to maintain a low current density and reduce the size while increasing the overall current handling capabilities of the dual FET. Application of the gate signal to both ends of gate fingers, for example, using a serpentine arrangement of the gate fingers and gate pads, simplifies layout of the dual FET device. A single integral ohmic metal finger including both source functions and drain functions reduces conductors and contacts for connecting the two devices at a source-drain node. Heat developed in the source, drain, and gate fingers may be conducted through the vias to the electrodes and out of the device.
1. A method for switching current using a control FET and a sync FET, the method comprising:
partitioning a current into a plurality of current segments;
distributing the plurality of current segments to sections of a control drain element of a control FET, the current segments distributed through a plurality of vias distributed along a surface of the control drain element;
distributing the plurality of current segments to sections of a control source element of a control FET, the current segments distributed through a plurality of vias distributed along a surface of the control source element;
coupling a control gate signal to a first and second end of a control gate finger disposed between the control drain element and a control source element of the control FET;
switching the plurality of current segments from the control drain element to the control source element using the control gate finger;
conducting the switched current segments along a continuous ohmic metal from the control source element of the control FET to a sync drain element of a sync FET; and
extracting the plurality of current segments from sections along the sync drain element through a plurality of vias distributed along a surface of the sync drain element.
2. The method of claim 1 , further comprising:
coupling a sync gate signal to both a first and a second end of a sync gate finger disposed between the sync drain element and a sync source element of the sync FET
switching the plurality of current segments from the sync drain element to the sync source element using the sync gate finger; and
extracting the switched current segments from sections along the sync source element through a plurality of vias distributed along a surface of the sync source element.
3. The method of claim 1 , further comprising removing heat from the control FET and the sync FET through a control drain electrode, a sync drain electrode, and a sync source electrode electrically coupled, respectively, to the control drain element, the sync source element, and the control drain element.
4. The method of claim 1 , wherein the control FET and the sync FET are fabricated on a piece of gallium arsenide or gallium nitride.