Texas Instruments Corporation

Shita Guo

Huanzhang Huang

Yonghui Tang

Yanfei Jiang

Yanli Fan

Douglas Edward Wente

Amit Rane

Mustafa Ulvi Erdogan

An eye expander that increases the transmitter linearity of Pulse-Amplitude Modulation 4-Level (PAM4) signals having an inner eye and two outer eyes. In embodiments, the eye expander includes a semi-linear gain stage that increases the eye height of the outer eyes. In some of those embodiments, the semi-linear gain stage includes a semi-linear gain input transistor having a base or gate coupled to an input terminal and a collector or drain coupled to an output terminal, a semi-linear gain resistor coupled to the emitter or source of the semi-linear gain input transistor, and semi-linear gain transistor-resistor pairs that selectively connect the emitter or source of the semi-linear gain input transistor to ground. In some embodiments, the eye expander includes a limiting gain stage that reduces the eye height of the inner eye and a linear gain stage that increases the eye height of the inner and outer eyes.

Eye expander for PAM4 signal linearization

Methods and systems of adaptive equalization to compensate channel loss are disclosed. A method includes detecting a peak amplitude of an equalizer output signal and selecting a set of reference voltage levels from M sets based on the peak amplitude of the equalizer output signal, each of the M sets having N reference voltage levels. The method includes continuing to increase an equalization level in predetermined steps to a next higher equalization level if the applied equalization level does not correspond to the over-equalization level and evaluating the distribution of the resulting hit counts for each increase to the next higher equalization level until the applied equalization level corresponds to the over-equalization level. The method includes decreasing to the previously applied lower equalization level if the applied equalization level corresponds to the over-equalization level.

Methods and systems for adaptive equalization with wide range of signal amplitudes

Aspects of the disclosure provide for a method. In some examples, the method includes detecting a transition in an input signal (IN), generating a bias current based on the detected transition in IN, and modifying a charge status of a capacitor based on the charge current. The method further includes generating an output signal (OUT) based on the charge status of the capacitor, disabling the bias current generation based on values of IN and OUT, and strongly pulling the capacitor up or down based on the disabling the bias current generation.

Delay cell

An apparatus includes a transistor with a control terminal, a first current terminal, and a second current terminal. The apparatus also includes a charge pump coupled to the control terminal of the transistor via a first and second paths. The first path comprises a first resistor and the second path comprises a second resistor in series with a diode. The first resistor has a higher resistance value than the second resistor.

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Shita Guo