Abstract: An eye margin test method includes receiving an analog input signal, receiving an analog input signal, generating a recovery clock signal based on the digital input signal, delaying the recovery clock signal by adjusting a first delay control code, obtaining a first delay margin code based on the delayed recovery clock signal, delaying the digital input signal by adjusting a second delay control code, obtaining a second delay margin code based on the delayed digital input signal, and obtaining an eye margin code by adding the first delay margin code and the second delay margin code.