We present the design and demonstration of unitraveling carrier (UTC) photodiodes fabricated using a novel quantum-well (QW) intermixing and metal-organic chemical vapor deposition (MOCVD) regrowth fabrication platform. The photodiodes discussed here were realized on the same chip as high gain centered QW active regions, intermixed passive centered well waveguides, and low optical confinement offset QW active regions regrown over intermixed wells. This demonstration lifts previous constraints imposed on high functionality photonic circuits, which forced a common waveguide architecture in the detector, laser, and amplifier by validating a platform suited for the monolithic integration of UTC photodiodes into photonic integrated circuits comprised of widely tunable high gain laser diodes, high efficiency modulators, and low optical confinement high saturation power semiconductor optical amplifiers. In this manuscript we focus on the design and performance of UTC photodiodes fabricated on intermixed QWs using this novel scheme. The photodiodes exhibit ∼90% internal quantum efficiency, excellent photocurrent handling capabilities, and minimal response roll-off over the 20 GHz of our testing capability. The 40 Gb/s operation was achieved with the demonstration of open eye diagrams.