Analog Devices, Inc.
Techniques for measuring slew rate in current integrating phase interpolator

Abstract:

An apparatus is described and includes a current integrating phase interpolator core having a programmable bias current; an AC-coupled inverter circuit coupled to an output of the current integrating phase interpolator core for receiving a signal comprising a periodic sawtooth waveform therefrom; a digital-to-analog (D/A) converter for setting an input common mode voltage of the AC-coupled inverter circuit; a duty cycle measurement (DCM) circuit for measuring a duty cycle distortion (DCD) of a rectangular wave clock signal output from the AC-coupled inverter circuit; and a circuit for computing a difference in the DCD of the rectangular wave clock signal when the input common mode voltage of the AC-coupled inverter circuit is set to a high voltage and when the input common mode voltage of the AC-coupled inverter circuit is set to a low voltage.