Patent attributes
An interpolator utilizes two ranks of transistors to generate a plurality of interpolator currents within the confines of a low power supply voltage. The first rank of transistors are underdriven, thereby generating a plurality of partially switched currents having shallow Gaussian-shaped functions. The partially switched currents are then spatially amplified by the second rank of transistors to reduce the overlap of the currents from adjacent transistors. The first rank of transistors are driven ratiometrically by the difference of two control currents, thereby eliminating errors caused by inaccurate resistors and current sources. A biasing op-amp senses the interpolator currents and servos the first rank of transistors, thereby regulating the interpolator currents to a value determined by a reference voltage which is temperature compensated. Thus, the biasing op-amp automatically compensates for temperature variations and manufacturing uncertainties in devices throughout the entire interpolator. A current generator utilizes a current mirror scheme and current replication techniques to cancel transistor alpha effects, thereby generating precise ratiometric drive currents from a low power supply voltage.
