Equalizer adaptation for data link

A retimer having an analog input, the receiver comprising:

• an adaptable continuous time equalizer (CTE) having a CTE signal input, a CTE control input, and a CTE output, the CTE signal input coupled to the analog input, and the CTE configured to filter an input signal at the analog input according to an adaptable filter characteristic, the adaptable filter characteristic based on a CTE setting received at the CTE control input;
• an adaptable discrete time equalizer (DTE) having a DTE signal input and a DTE control input, the DTE signal input coupled to the CTE output;
• and
• logic circuitry coupled to the CTE control input and to the DTE, the logic circuitry configured to:
• determine a gain of the DTE;
• determine whether the gain has increased or decreased by more than a threshold amount;
• responsive to a determination that the gain has increased or decreased by more than the threshold amount, sequentially configure the CTE for multiple CTE settings such that gain of the CTE is caused to increase or decrease in a same direction with the change in gain of the DTE;
• determine a separate figure of merit (FOM) for each of the multiple CTE settings;
• select a new CTE setting from the multiple CTE settings based on the FOM for each of the multiple CTE settings;
• and
• provide the new CTE setting to the CTE control input.

A method for adapting a continuous time equalizer (CTE), the method comprising:

• determining a gain of a discrete time filter;
• determining whether the gain has increased or decreased by more than a threshold amount;
• responsive to determining that the gain has increased or decreased by more than the threshold amount, sequentially configuring the CTE for multiple CTE settings such that gain of the CTE is caused to increase or decrease in a same direction with the change in gain of the DTE;
• determining a separate figure of merit (FOM) for each of the multiple CTE settings;
• and
• selecting a new CTE setting from the multiple CTE settings based on the FOM for each of the multiple CTE settings.