Monitor circuitry for decision feedback equalized receiver

Abstract

Decision feedback equalization (DFE) is used to help reduce inter-symbol interference (ISI). Additional equalization may also be applied to an input signal using analog front-end (AFE) circuitry with, for example, a continuous-time linear equalizer (CTLE) and/or a variable-gain-amplifier (VGA). Circuitry replicating the receiver AFE is provided with the same gain setting and an offset correction signal as the receiver AFE circuitry. In addition, a common-mode DFE tracking signal is used to correct for common-mode offsets introduced by the DFE tap values. In this manner, as a monitor threshold voltage provided to the input of the replica AFE circuitry is adjusted (e.g., swept), the AFE replica and common-mode DFE tracking compensate for gain variation and common-mode offsets introduced by the AFE circuitry and common-mode offsets due to DFE tap values thereby reducing the inaccuracies in signal eye measurements that would otherwise be introduced without these compensations/tracking.

Dependencies are inferred from the claim text.