A fully digital pulse width modulator substantially doubles resolution in
a laser printer by outputting data to the laser on both the rising and
falling edges of the clock cycle. A counter and the clock itself are used
to select input to a multiplexer, and consequently, the data output to
the laser from the multiplexer. A data selector code, generated by
concatenating the binary value of the counter and the inverted clock
bitwise, selects which of the 16 bits representing a pixel to place onto
the data line, so that all 16 bits are output to the laser serially and
sequentially in eight clock cycles. By using both the rising and falling
edges of a clock cycle, the clock speed of the device is effectively
doubled, without increasing actual clock speed. Device resolution is
improved simply and inexpensively without major modification of printed
circuit boards.