Patent ID: 9485084
Filing Date: 2016-11-01
CPC Classification: H03K,H03L,H04L

Claim Text:
1. A phase interpolator, comprising: a pair of load resistors coupled to a supply voltage; a first portion including a first plurality of branches, a plurality of tail current sources, and a plurality of source nodes, each branch of the first plurality of branches including a differential pair of transistors and a different one of the tail current sources of the plurality of tail current sources, wherein source terminals of differential pairs of transistors connect to form the plurality of source nodes, wherein each tail current source of the plurality of tail current sources couples to one of the plurality of source nodes, and wherein the differential pair of transistors and the plurality of tail current sources are configured in a current coding scheme; a second portion including a second plurality of branches and a fixed current source coupled to the second plurality of branches, each branch of the second plurality of branches including a second plurality of differential pairs of transistors and a plurality of switches configured in a size coding scheme, wherein each switch of the plurality of switches is coupled to and used to turn on or off a corresponding differential pair of transistors of the second plurality of differential pairs of transistors, wherein the second plurality of differential pairs of transistors in said each branch of the second plurality of branches receives differential input signals with a particular phase that results from equally dividing 360 degrees by a total number of the second plurality of branches, and wherein switches in two adjacent branches of the second plurality of branches are turned on to produce differential output signals having a desired phase between particular phases of the two adjacent branches; wherein the first portion and the second portion are coupled to each other and to the pair of load resistors.