Patent ID: 6597207
Filing Date: 2003-07-22
Classification: H03F,H03K

Abstract:
A vernier that converts a differential input signal to a differential output current with a conversion gain that corresponds to a digital command signal, comprising:first, second and third current sources that respectively provide first, second and third currents. an input differential pair of first and second input transistors arranged to steer said third current along first and second current paths in response to said differential input signal; first and second reference transistors that have first and second reference device sizes and that respectively couple said first current path to said first current source and couple said second current path to said second current source; and at least one pair of first and second subtraction transistors that have first and second subtraction device sizes that are less than said first and second reference device sizes and that, in response to said digital command signal, respectively couple said first current path to said second current source and couple said second current path to said first current source; wherein said differential output current is generated by differences between said first and second currents and those portions of said third current that are directed towards or away from said first and second current sources.