Transmitter-only IC chip having external loopback test function and external loopback test method using the same

A transmitter-only IC chip with an external loopback test function, comprising:

• a plurality of serializers for converting original parallel data applied to each of a plurality of channels into serial data, respectively, in response to a conversion clock;
• drivers mounted on the transmitter-only IC chip for outputting the serial data outputted from each of the serializers through corresponding transmit pads;
• and
• a loopback test circuit for receiving serial data as external loopback data through one of the transmit pads set as a receive pad for a test, the serial data transmitted through one of the remaining transmit pads, recovering the received external loopback data into parallel data, and then comparing the restored parallel data with the original parallel data,
• wherein the loopback test circuit comprises:
• a pattern generator for generating the original parallel data;
• a receive buffer connected to the receive pad and enabled to receive the serial data when a corresponding driver is disabled;
• a parallelizer for recovering external loopback data outputted from the receive buffer into parallel data in response to an applied deskew clock;
• a deskewer for applying the deskew clock to the parallelizer;
• and
• a pattern comparator for comparing the parallel data outputted from the parallelizer with the original transmit data.

An external loopback test method in a transmitter-only IC chip including drivers for transmitting data through transmit pads that are installed in correspondence to a plurality of channels, the method comprising:

• providing a receive buffer connected to one of the transmit pads for a loopback of the transmitted data;
• and
• obtaining a loopback test result by comparing external loopback data outputted from the receive buffer with original transmit data of the transmitted data,
• wherein, when the transmitted data are serial data outputted through a serializer, the external loopback data are recovered into parallel data using a conversion clock applied to the serializer and then compared, during the recovering of the parallel data, the conversion clock is generated as a plurality of delay clocks through a plurality of delay taps of a deskewer in order to remove skew.