Gigabit passive optical networks (GPON) are being seriously considered for delivery of Triple-play services (video, voice, data) throughout the world. There is much debate over which technology — avalanche photodiode (APD) receivers or standard receivers with forward error correction (FEC) — is the best solution for meeting link budgets and cost targets at the user location (the Optical Network Terminal, or ONT). Receivers implementing APDs can easily meet sensitivity requirements, but at high cost. FEC adds some cost and complexity to implement the encoding and decoding, but is generally much less expensive.

This application note provides a brief explanation of how FEC works and illustrates the impact of jitter on a receiver’s sensitivity when FEC is used. The note also presents actual test data to show the expected performance when using two different types of receiver circuits.