The RX analog front end (AFE) is a high-speed input differential buffer with configurable RX termination voltage, on-chip coupling capacitors, and calibrated termination resistor. When the on-chip coupling capacitor is used, a level shifter circuit is also enabled to maintain DC balance when receiving unbalanced patterns.
AC Coupling Mode
This is the typical and default transceiver operation mode. In this use mode, the external AC coupling capacitor must be present and should follow data sheet recommendations. The device's internal capacitor is bypassed. The termination voltage is set to VCOM_VREF provided by CTLE.
Use Mode | External AC Coupling | Termination Voltage | Setting |
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AC Coupling | Yes | VCOM_VREF (typically 590 mV) |
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DC Coupling Mode with GTM_AVTT Termination
This mode enables an internal AC capacitor circuit that decouples the analog front end from the equalization block, allowing greater flexibility on the common mode input voltage. The TX or board circuit should ensure that the RX input common mode voltage is set to between 0.6V ~ 1.0V.
Use Mode | External AC Coupling | Termination Voltage | Setting |
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DC Coupling | No | GTM_AVTT |
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DC Coupling Mode with GND Termination
This mode enables an internal AC capacitor circuit that decouples the analog front end from the equalization block, allowing greater flexibility on the common mode input voltage. The TX or board circuit should ensure that the RX input common mode voltage is set to between 0.2V ~ 0.6V.
Use Mode | External AC Coupling | Termination Voltage | Setting |
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DC Coupling | No | GND |
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DC Coupling Mode with FLOAT Termination
This mode enables an internal AC capacitor circuit that decouples the analog front end from the equalization block, allowing greater flexibility on the common mode input voltage. The TX or board circuit should ensure that the RX input common mode voltage is set to between 0.2V ~ 1.0V.
Use Mode | External AC Coupling | Termination Voltage | Setting |
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DC Coupling | No | FLOAT |
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