Abstract: A Sigma Rho A/D converter (10) includes a transconductance element (R) having an input node for receiving an input voltage signal V.sub.in and an output node providing an analog current I.sub.in ; a charge integrator (12) having an input coupled to the output node, the charge integrator having feedback provided by an integrating capacitor C and an output node providing an output signal V.sub.o ; and a clocked voltage comparator (14) having an input coupled to V.sub.o for comparing V.sub.o to a reference potential. An output of the comparator updates in response to an occurrence of a first clock signal CLK1. A current sink (16) is switchably coupled to the output node of the transconductance element as a function of the logic state of the output of the comparator.

Abstract: Low noise polycrystalline silicon resistors are fabricated in the following sequence:(1) deposit an appropriate thickness of polysilicon (e.g. 400 nm) on top of an oxidized wafer(2) resistor doping by ion implantation (e.g. phosphorous)(3) heavy doping of the end-contact regions of the polysilicon resistor by high-dose ion implantation(4) patterning the polysilicon resistor(5) oxidation/annealing the polysilicon resistor(6) open contacts to the polysilicon resistor(7) aluminum metallization to form ohmic contacts(8) a long (e.g. 3 hours) low temperature (e.g. at 375.degree.) pure hydrogen annealing to passivate the interface states in the polysilicon resistor. Polyresistors processed this way have a noise figure that is about a factor of three lower than samples processed otherwise. The low temperature post metallization annealing in pure hydrogen passivates the interfaces of polyresistors, reducing the l/f noise normally generated therein.