A depletion-mode current source having a saturation current of sufficient accuracy for use as a pre-charge circuit in a start-up circuit of an AC-to-DC power converter is fabricated using an enhancement-mode-only process. The depletion-mode current source can be fabricated on the same integrated circuit (IC) as a gallium nitride field-effect transistor (FET) and resistive and capacitive components used in the start-up circuit, without affecting the enhancement-mode-only fabrication process by requiring additional masks or materials, as would be required to fabricate a depletion-mode FET on the same IC as an enhancement-mode FET. The current source includes a resistive patterned two-dimensional electron gas (2DEG) or two-dimensional hole gas (2DHG) channel coupled between two terminals and one or more metal field plates extending from one of the terminals and overlying the patterned area of the channel, the field plates being separated from the channel and from each other by dielectric layers.

A semiconductor device includes a semiconductor die, an N-doped region, an N-contact metal, a PN junction mesa, a P-contact metal, a first passivation layer, an anode feed metal, and a cathode feed metal. The semiconductor die may include a plurality of semiconductor layers disposed on an insulating substrate. The N-doped region may define an active area of the device. The N-contact metal may be disposed on a first portion of the N-doped region. The PN junction mesa may be disposed on a second portion of the N-doped region. The PN junction mesa may comprise a hyperabrupt N-doping layer disposed on the first portion of the N-doped region and a P-doped layer disposed on the hyperabrupt N-doping layer. The P-contact metal may be disposed on the P-doped layer of the PN junction mesa. The first passivation layer may cover the semiconductor layers of the semiconductor device and have openings for the N-contact metal and the P-contact metal. The anode feed metal may connect the P-contact metal to a first bond pad. The anode feed metal generally forms an arch from the P-contact metal to the first bond pad and the arch defines a space between the anode feed metal and the first passivation layer covering the semiconductor layers and a the of the PN junction mesa.

The present disclosure generally relates to a resistor structure having a charge control layer. In an example, an integrated circuit includes a semiconductor substrate, a dielectric layer, a first contact, a second contact, and a charge control layer. The semiconductor substrate includes a semiconductor hetero-structure. The dielectric layer is disposed over the semiconductor substrate. The first contact is disposed through the dielectric layer and contacting the semiconductor hetero-structure. The second contact is disposed through the dielectric layer and contacting the semiconductor hetero-structure. The second contact is disposed laterally separated from the first contact. The charge control layer is disposed over the semiconductor hetero-structure and laterally between the first contact and the second contact. At least a portion of the dielectric layer is disposed between the charge control layer and the semiconductor hetero-structure.

A variable capacitance III-N device having multiple two-dimensional electron gas (2DEG) layers are described. In some embodiments, the device comprises a first source and a first drain; a first polarization layer adjacent to the first source and the first drain; a first channel layer coupled to the first source and the first drain and adjacent to the first polarization layer, the first channel layer comprising a first 2DEG region; a second source and a second drain; a second polarization layer adjacent to the second source and the second drain; and a second channel layer coupled to the second source and the second drain and adjacent to the second polarization layer, the second channel layer comprising a second 2DEG region, wherein the second channel layer is over the first polarization layer.

A variable capacitance III-N device having multiple two-dimensional electron gas (2DEG) layers are described. In some embodiments, the device comprises a first source and a first drain; a first polarization layer adjacent to the first source and the first drain; a first channel layer coupled to the first source and the first drain and adjacent to the first polarization layer, the first channel layer comprising a first 2DEG region; a second source and a second drain; a second polarization layer adjacent to the second source and the second drain; and a second channel layer coupled to the second source and the second drain and adjacent to the second polarization layer, the second channel layer comprising a second 2DEG region, wherein the second channel layer is over the first polarization layer.

A heterostructure semiconductor device includes first and second active areas, each electrically isolated from one another, and each including first and second active layers with an electrical charge disposed therebetween. A power transistor is formed in the first active area, and an integrated gate resistor is formed in the second active area. A gate array laterally extends over the first active area of the power transistor. First and second ohmic contacts are respectively disposed at first and second lateral ends of the integrated gate resistor, the first and second ohmic contacts are electrically connected to the second portion of the second active layer, the second ohmic contact also being electrically connected to the gate array. A gate bus is electrically connected to the first ohmic contact.

Aspects generally relate to a P.sup.N junction varactor that can be integrated with high electron mobility transistor (HEMT) in a single device or die. The varactor and HEMT are fabricated with different materials forming various layers of the varactor and HEMT. Using different material stack-up to form the varactor and HEMT allows characteristics of the varactor and HEMT to be varied for improved performance in different operating scenarios. The integrated varactor and HEMT device may be used for RF circuits, such as radio frequency front end (RFFE) devices for use in 5G.

A variable capacitance III-N device having multiple two-dimensional electron gas (2DEG) layers are described. In some embodiments, the device comprises a first source and a first drain; a first polarization layer adjacent to the first source and the first drain; a first channel layer coupled to the first source and the first drain and adjacent to the first polarization layer, the first channel layer comprising a first 2DEG region; a second source and a second drain; a second polarization layer adjacent to the second source and the second drain; and a second channel layer coupled to the second source and the second drain and adjacent to the second polarization layer, the second channel layer comprising a second 2DEG region, wherein the second channel layer is over the first polarization layer.

A heterostructure semiconductor device includes first and second active areas, each electrically isolated from one another, and each including first and second active layers with an electrical charge disposed therebetween. A power transistor is formed in the first active area, and an integrated gate resistor is formed in the second active area. A gate array laterally extends over the first active area of the power transistor. First and second ohmic contacts are respectively disposed at first and second lateral ends of the integrated gate resistor, the first and second ohmic contacts are electrically connected to the second portion of the second active layer, the second ohmic contact also being electrically connected to the gate array. A gate bus is electrically connected to the first ohmic contact.

A heterostructure semiconductor device includes first and second active areas, each electrically isolated from one another, and each including first and second active layers with an electrical charge disposed therebetween. A power transistor is formed in the first active area, and an integrated gate resistor is formed in the second active area. A gate array laterally extends over the first active area of the power transistor. First and second ohmic contacts are respectively disposed at first and second lateral ends of the integrated gate resistor, the first and second ohmic contacts are electrically connected to the second portion of the second active layer, the second ohmic contact also being electrically connected to the gate array. A gate bus is electrically connected to the first ohmic contact.