The purpose of receiver equalization is to compensate for channel insertion loss and inter-symbol interference in the system before the input of the TUSB1146. The receiver overcomes these losses by attenuating the low frequency components of the signals with respect to the high frequency components. The proper gain setting should be selected to match the channel insertion loss before the input of the TUSB1146 receivers. Two 4-level inputs pins enable up to 16 possible equalization settings. USB3.1 upstream path, USB3.1 downstream path, and DisplayPort each have their own two 4-level inputs. The TUSB1146 also provides the flexibility of adjusting settings through I²C registers.

The TUSB1146 implements three different equalizer features for the USB-C downstream facing port receivers (RX1 and RX2): Fixed EQ, Fast Adaptive EQ (Fast AEQ), and Full Adaptive EQ (Full AEQ). The default operation is Fixed EQ. In Fixed EQ operation, a single setting is used for all possible devices (with and without cable) inserted into the USB-C receptacle. The Fast AEQ feature will distinguish between a short channel and a long channel. A short channel represents a low loss use case of a USB 3.1 device plugged directly into USB-C receptacle without a cable. A long channel represents the high loss use case of the USB 3.1 device plugged into the receptacle through a USB cable. In Fast AEQ mode, TUSB1146 will select between two pre-determined settings based on whether or not channel is short or long. When TUSB1146 is configured for Full AEQ, the TUSB1146 will automatically determine the best equalization setting each time a USB device is inserted into the USB-C receptacle. In Full AEQ mode, the TUSB1146 will always determine the best settings regardless if the channel is short, long or somewhere in between. The Full AEQ feature is disabled by default but can be enabled through a register.