Interleaved time-division multiplexor with phase-compensated frequency

Abstract

A synchronous, interleaved, time-division M:1 multiplexor. Following an input stage of parallel synchronous latches for latching M incoming parallel data bits (where M is an integer power of two equal to or greater than four) is an intermediate stage of parallel synchronous latches. The intermediate latches are clocked with selected phases of an M-phase clock having M equally-spaced phases of a clock signal having a frequency of B/M (where B is the outgoing bit rate) to latch each bit at a time at least 2/B (i.e., two outgoing bit periods) after such bit is received from its respective input latch. A first stage of 2:1 multiplexors, following the intermediate latches and used to begin multiplexing the latched bits, are clocked with selected phases of the M-phase clock to begin multiplexing each bit at a time at least 1/B (i.e., one outgoing bit period) after such bit is received from its respective intermediate latch. Further stages of 2:1 multiplexors complete the multiplexing and are each clocked with clock signals which are successively doubled in frequency at each additional stage of 2:1 multiplexors (e.g., 2B/M, 4B/M, 8B/M, . . . ) and phase compensated so as to align the clock signals with their respective data. The phase-compensated, frequency doubling for each 2:1 multiplexor stage is done by 'exclusive-ORing' pairs of quadrature clock signals from the immediately preceding 2:1 multiplexor stage.