Embodiments of a digital potentiometer are disclosed that require lesser
numbers of components than conventional digital potentiometers. A first string
of elemental impedance devices, and at least one bulk impedance device, are provided
between first and second reference terminals. The first string of elemental impedance
devices is tapped by wiper switches. The at least one bulk impedance device has
an impedance greater than an impedance of the first string. If desired, second
and third bypassable impedance device strings also may be provided between the
first and second reference terminals, with the impedance of the respective second
and third strings being between the impedance of the first string and the impedance
of one bulk impedance device. One or more dummy structures each including an impedance
device in parallel with a permanently-on switch also may be between the first and
second reference terminals to improve linearity.