Lateral varactor with staggered punch-through and method of fabrication
First Claim
1. A lateral varactor with staggered punch-through levels, comprising:
- an active layer disposed over a substrate; and
an anode and a cathode disposed on said active layer;
said anode having at least first and second sections, with the punch-through between said first section and said substrate occurring at a greater voltage than the punch-through between said second section and said substrate.
1 Assignment
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Accused Products
Abstract
A lateral varactor is fabricated with a recess structure that provides staggered punch-through points, enabling the varactor to be tuned through punch-through without significant non-linearities in either capacitance or Q. The lateral varactor (30) includes a cathode (32) and an anode (40) disposed on the surface of an active layer (12). The anode (40) includes a surface section (45), and a recess section (46) disposed within a recess area (50). This recess structure results in a greater active layer depth under the anode surface section (45) than under the anode recess section (46). As a result, as reverse-bias voltage on the anode increases, the depletion region (60) reaches punch-through under the anode recess section (46) prior to reaching punch-through under the anode surface section (45). As a result, varactor capacitance depends upon the contributions associated with each anode section and sidewall capacitance, so that the abrupt impedance changes caused by tuning the varactor through a punch-through point is reduced, and varactor tuning is made more continuous.
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Citations
13 Claims
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1. A lateral varactor with staggered punch-through levels, comprising:
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an active layer disposed over a substrate; and an anode and a cathode disposed on said active layer; said anode having at least first and second sections, with the punch-through between said first section and said substrate occurring at a greater voltage than the punch-through between said second section and said substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification