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US 6,388,530 B1Granted
Microwave amplifier implemented by heterojunction field effect transistors
AssigneeNEC Corporation
InventorsTakeshi Nishimura, Naotaka Iwata
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Abstract
A microwave amplifier circuit controls the output power thereof depending upon an associated transmitter of a wireless telephone, and a main amplifier transistor and switching transistors of a drain bias controlling circuit are implemented by gallium-arsenide heterojunction field effect transistors so that, even if they are integrated on a single compound semiconductor substrate, the microwave amplifier circuit achieves a high power efficiency over a wide output voltage range.
Claims7
A microwave amplifier circuit comprising
- a field effect transistor serving as a main amplifier,
- a drain bias controlling circuit including
- a power source for generating an electric power and
- a de-to-dc converter electrically connected between said power source and a drain node of said field effect transistor so as to vary a drain voltage applied to said drain node,
- a gate bias circuit connected to a gate electrode of said field effect transistor and a gate bias terminal where a gate bias voltage is applied, and
- a gate bias controlling circuit connected between said power source and said gate bias circuit and supplying an electric current to said gate bias circuit so as to keep a drain current at said drain node constant even when said drain voltage is lowered under a critical value.
3 more elements
Dependencies are inferred from the claim text.