Apparatus and methods for accurate latency measurements in integrated circuits

An integrated circuit comprising:

• physical media attachment circuitry that deserializes a serial data stream to generate data words;
• a bitcounter circuit that increments a bitcount by a number of bits in the data words;
• a frame start detect circuit in a decoding circuit block that receives the data words and detects a bit location in a data word that begins a frame;
• a bitcount locate circuit that uses the bitcount and the bit location to determine a frame start bitcount that is fed back to the physical media attachment circuitry;
• and
• pulse generate circuitry in the physical media attachment circuitry that receives the frame start bitcount and generates and transmits an asynchronous pulse.

A method for performing a latency measurement within an integrated circuit, the method comprising:

• incrementing a bitcounter by a number of bits in data words received;
• outputting a bitcount sequence from the bitcounter, wherein a synchronous signal comprises the bitcount sequence;
• transmitting an asynchronous signal upon occurrence of a predetermined count in the bitcount sequence;
• and
• having the synchronous signal follow the data words in a synchronous manner as the data words are processed by receiver processing circuitry.