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Hybrid Flip Flop

IP.com Disclosure Number: IPCOM000081884D
Original Publication Date: 1974-Aug-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Wiedmann, SK: AUTHOR

Abstract

Fig. 1 shows the electric circuit diagram of a flip-flop made up of bipolar and unipolar transistors. The flip-flop is symmetrically designed. Each storage field-effect transistor (FET) 1 and 2 is provided with a bipolar transistor 3 and 4, respectively, which serve as load devices. In the example shown, N-channel FETs with PNP bipolar transistors are used as storage FETs.

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Hybrid Flip Flop

Fig. 1 shows the electric circuit diagram of a flip-flop made up of bipolar and unipolar transistors. The flip-flop is symmetrically designed. Each storage field- effect transistor (FET) 1 and 2 is provided with a bipolar transistor 3 and 4, respectively, which serve as load devices. In the example shown, N-channel FETs with PNP bipolar transistors are used as storage FETs.

Standby current Io is impressed into the linked emitters of bipolar transistors 3 and 4. The bases of bipolar transistors 3 and 4, as well as the sources of FETs 1 and 2, are connected to common operating voltage Vs. FETs 1 and 2 are cross-coupled with regard to their gate and drain terminals, thus providing a latch function. By decoupling elements, not shown, such as N-channel FETs, at nodes a and b the flip-flop can be extended in a known manner to a selectable storage cell.

An important feature of this hybrid flip-flop is that FETs 1 and 2 comprise drain-substrate connections 5 and 6. Thus threshold voltage VT of the FETs must be kept at a value lower than a diode forward voltage. This requirement is preferably met by known implantation techniques, which permit the doping rate to be adjusted very accurately.

Figs. 2 and 3, respectively, show a plan view and a sectional view of the typical layout of the flip-flop of Fig. 1. As can be seen, a considerable overall area reduction is obtained by merging the semi-conductor zones of the bipolar and the unipolar transistors.

In Fig...