US Patent 10554453 Quarter-rate charge-steering decision feedback equalizer (DFE)

A decision feedback equalizer (DFE) comprises four charge-steering (CS) primary latches and four primary taps. Two of the four CS primary latches are driven by complementary in-phase quarter-rate clocks and the other two of the four CS primary latches are driven by complementary quadrature quarter-rate clocks. No element of the DFE is driven by any half-rate clocks. In some implementations, each of the primary latches including a respective differential pair of n-channel output transistors and each primary tap includes a respective differential pair of p-channel input transistors connected via their gate nodes to a respective one of the four CS primary latches. In other implementations, each of the primary latches including a respective differential pair of p-channel input transistors and each primary tap includes a respective differential pair of n-channel output transistors connected via their gate nodes to a respective one of the four CS primary latches.