PN junction integrated varactors for RF applications at different standard frequencies

<title>DC modeling of PN integrated cross varactors</title>

“…The varactors have been fabricated together with a measurement structure in order to use the Cascade ACP40 GSG microprobes. The de-embedding process is used to move the measurement reference plane from the calibration point (probe tips) to the DUT (Device Under Test) [12].…”

“…The square island configuration is normally used when a varactor is implemented with PN junction. These varactors require a huge amount of area in order to offer a typical tuning range from ±10% to ±20% [6] one solution is to increase the perimeterper-unit-area longer than in a square island configuration, such as, interdigitated varactors [10] and cross varactors can be used: both geometries show an enhanced P + to N-well lateral contact surface, reducing the area occupied.…”

“…the effect of the corner is neglected). Thus, the cross capacitance C c is approximated by, (10) And the mutilated cross capacitance C m by, (11) where the first terms correspond to the area capacitance, and the second ones to the lateral capacitance; X jp is the depth of the diffusion and W is the depletion region width.…”

“…In this model the effect of the corner in the lateral capacitance is taking into account through equation (9), where the region arms do not perform as parallel-plate capacitors any more. Therefore, for the cross varactors: (12) And for the mutilated cross varactors, (13) where the first terms correspond to the area capacitance, and the second ones to the lateral capacitance; L m = L-W; L M = L-2X p and X p is the depletion region width in the P + semiconductor.…”