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US 4,394,769 AGranted
Dual modulus counter having non-inverting feedback
AssigneeHughes Aircraft Company
InventorJohn M. Lull
Life of this patent
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Abstract
The ring counter of this invention is self-initializing and is operable at a clock frequency corresponding to four gate delays and comprises a plurality of master of slave flip-flops, in which this high speed capability is attained by using non-inverting feedback between the first and last flip-flops and by operating the master and slave of each in complementary fashion without requiring the use of a complementary clock signal. The non-inverting feedback takes advantage of the inherent delay between the response of the complementary outputs of each flip-flop.
Claims11
A self-initializing ring counter, comprising:
- (A) means for receiving a clock signal;
- (B) a plurality of n flip-flops, each of said flip-flops, comprising:
- (1) a master and a slave each having its own clock input, the clock inputs of both being connected to receive the same clock signal, said master and slave being enabled by said clock signal at different times, and
- (2) an R input, an S input, a Q output and a Q output;
- (C) said plurality of said n flip-flops being connected in serial succession, whereby the Q and Q outputs of each flip-flop are connected to the R and S inputs respectively, of the next successive flip-flop;
- and
- (D) said counter having a non-inverting feedback, comprising:
- (1) first means coupling the Q outputs of the (n-1).sup.th flip-flop and (n-2).sup.th flip-flop to the S input of the (1).sup.st flip-flop, and
- (2) second means coupling the Q outputs of the (n-1).sup.th flip-flop and the (n).sup.th flip-flop to the R input of the (1).sup.st flip-flop.
6 more elements
Dependencies are inferred from the claim text.