US 5,329,181 A · Complementary macrocell feedback circuit

Abstract

In a programmable logic device having I/O blocks and logic blocks, two lines leading from a region including a logic block and an I/O block alternately provide a logic block output signal and its complement or a logic block output signal and an I/O block input signal. A multiplexer selects between providing on a line leading from an I/O block to an interconnect structure a first signal which is provided by the I/O block when the I/O block is an input buffer and a second signal which is the inverse of a logic signal provided to the I/O block when the I/O block is not an input buffer. Thus in one case two lines which extend from the I/O block to the interconnect structure may carry a) a logic block output signal and b) an I/O block output signal; and in the other case carry a) a logic block output signal and b) the inverse of the logic block output signal.

Claims4

Dependent claims

A feedback circuit comprising:

a first line (14) for providing a logic block output signal;
a second line (16) for providing a second signal;
means (24) for generating the complement of said logic block output signal;
a third line (23);
and
means (22) for providing on said third line a selected one of said complement of said logic block output signal and said second signal;
an interconnect structure (11);
and
means (19) for programmably connecting said first line and said third line to said interconnect structure.

6 more elements

Dependencies are inferred from the claim text.

Complementary macrocell feedback circuit

Life of this patent

Complementary macrocell feedback circuit

Life of this patent

Abstract

Claims4