An apparatus and method relate generally to generation and checking of a quaternary pseudo random binary sequence (“QPRBS”). In an apparatus, there is a pseudo random binary sequence (“PRBS”) generator configured to receive a seed of a PRBS to be generated. A mask generator is configured to generate a mask output corresponding to the PRBS. The PRBS generator and the mask generator are both configured for sequential operation with respect to one another. A masking circuit is configured to receive the mask output and the PRBS to bitwise mask the PRBS with the mask output to generate the QPRBS.