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-Q1. The receiver overcomes these losses by attenuating the low-frequency components of the signals with respect to the high frequency components. Select the proper gain setting to match the channel insertion loss before the input of the TUSB1146-Q1 receivers. Two 4-level inputs pins enable up to 16 possible equalization settings. USB3.2 upstream path, USB3.2 downstream path, and DisplayPort each have two 4-level inputs. The TUSB1146-Q1 also provides the flexibility of adjusting settings through I²C registers.

The TUSB1146-Q1 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 can distinguish between a short channel and a long channel. A short channel represents a low loss use case of a USB 3.2 device plugged directly into USB-C receptacle without a cable. A long channel represents the high loss use case of the USB 3.2 device plugged into the receptacle through a USB cable. In Fast AEQ mode, the TUSB1146-Q1 selects between two pre-determined settings based on whether or not channel is short or long. When the TUSB1146-Q1 is configured for Full AEQ, the TUSB1146-Q1 automatically determines the best equalization setting each time a USB device is inserted into the USB-C receptacle. In Full AEQ mode, the TUSB1146-Q1 always determines 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.