Abstract: A parallel trimming method and apparatus are provided for a voltage controlled delay loop. A plurality of delay units in a voltage controlled delay loop are trimmed. Each delay unit comprises a delay element and a latch buffer. A reference signal is applied to each of the delay units and a position of an edge (such as a rising or falling edge) associated with each of the delay units is identified. The edges of the delay units are then aligned by adjusting a trim setting of the respective latch buffer.

Abstract: Methods and apparatus are provided for digital linearization of an analog phase interpolator. Up to 2N desired phase values are mapped to a corresponding M bit value, where M is greater than N. A corresponding M bit value is applied to the phase interpolator to obtain a desired one of the 2N desired phase values. A linearized phase interpolator is also provided that accounts for process, voltage, temperature or aging (PVTA) variations.

Abstract: Methods and apparatus are provided for monitoring a data eye associated with a received signal. A plurality of samples of the received signal are obtained for each unit interval based on a clock recovered from the received signal, to obtain an estimate of the data eye. According to one aspect of the invention, the samples are obtained substantially simultaneous to a decoding of the received signal. The collected data eye samples can optionally be processed, for example, to collect statistics on the received signal or to determine a distribution of the received signal.

Abstract: The present invention is used to automatically calibrate a SERDES device by utilizing information provided in the eye diagram of the received signal. In particular, the invention mitigates the components of determininistic jitter, such as ISI and frequency distortion. To achieve this goal, the invention enables the receive side of the SERDES to evaluate the quality of the eye received using a cost function. The invention calculates the cost function associated with the received data and then uses this information to effect an auto calibration of the SERDES device.

Abstract: Methods and apparatus are provided for trimming a desired delay element in a voltage controlled delay loop. The disclosed trimming process comprises the steps of obtaining a first phase signal of a reference clock; applying the first phase signal along a first path to the desired delay element and a common delay element connected in series to the desired delay element; applying the reference clock along a second path to a first delay element and the common delay element; measuring a delay difference between the first and second paths at an output of the common delay element; and adjusting a delay of the desired delay element based on the measured delay difference. The trimming method may be repeated for each delay element in a voltage controlled delay loop.

Abstract: A pre-distorter that compensates for amplitude and phase distortion created by an amplifier. During a training session, the amplifier is stimulated with input signals of pre-selected amplitude and phase at various temperatures and the amplifier output is captured and converted into data sets. Polynomials are then fitted to the data sets and inverses of the polynomials are determined. The coefficients of the inverse polynomials are then saved for each temperature. During operation, the amplifier temperature is predicted based on the amplifier input signal and the coefficients associated with the predicted temperature are selected to be applied to the input signal to compensate for amplitude and phase distortion caused by the amplifier.

Abstract: In training a SERDES, a Common Electrical Interface (CEI) training frame, having certain bits of information embedded therein, is transmitted over a path which comprises transmitter, channel, and receiver components. The present invention analyzes the resulting received signal and determines the effective aggregate channel impulse response of these three components. The invention then determines an estimate of the inverse of this aggregate channel and uses this determination to reduce distortions that have been introduced into a signal that has been transmitted over the path.