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PNP Junction Field Effect Transistor

IP.com Disclosure Number: IPCOM000086304D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Ayers, RL: AUTHOR [+3]

Abstract

A gated transistor having low-input current and high-current output is achieved by incorporating a junction field-effect transistor (JFET) in the inactive base region of a bipolar transistor, typically a lateral PNP. The characteristics of the combined JFET and lateral PNP provides an I(c)V(cE) characteristic that has a negative resistive characteristic dependent upon the gate voltage.

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PNP Junction Field Effect Transistor

A gated transistor having low-input current and high-current output is achieved by incorporating a junction field-effect transistor (JFET) in the inactive base region of a bipolar transistor, typically a lateral PNP. The characteristics of the combined JFET and lateral PNP provides an I(c)V(cE) characteristic that has a negative resistive characteristic dependent upon the gate voltage.

Fig. 1 shows a highly doped N+ sublayer 10 incorporated in a P-type substrate 12. A lightly doped N region 14 is epitaxially grown on the substrate
12. The layer 14 forms base and channel regions of a lateral PNP JFET to be described. P+ isolation regions 16 are incorporated into the region 14 to define a plurality of device areas. A plurality of P regions are introduced into the substrate 14 by diffusion or the like after appropriate masking.

P regions 18 and 20 form the emitter and collector, respectively, of a PNP transistor. A P region 22 forms the variable gate of a JFET. The fixed bias gate of the JFET is formed by the P substrate 12 and the p+ isolation 16. An N+ ohmic contact 24 is defined such that the P gate 22 is between the contact 24 and the active base region of the lateral PNP.

Fig. 2 shows a top view of Fig. 1. By biasing the base-substrate/ isolation junction in the reverse mode, a depletion layer X1 extends upward and into the N channel region where stopped by the N+ sublayer 10. The variable gate 22 extends from the depletion layer X1 on one side of the cell to the opposite...