Abstract: A five-level feed-back digital-to-analog converter (DAC) in a switched capacitor sigma-delta analog-to-digital converter has an improved switching sequence that boosts from two to five the number of quantization levels of the feed-back DAC. Switching sequences are used to obtain five equally distributed charge levels C*VREF, C*VREF/2, 0, ?C*VREF/2 and ?C*VREF. When summed with an input voltage, VIN, the five-level feed-back DAC produces five equally distributed output voltages of A*VIN+VREF, A*VIN+VREF/2, A*VIN+0, A*VIN?VREF/2 and A*VIN?VREF, where A is gain, VIN is the input voltage, and VREF is the reference voltage.

Abstract: A differential input operational amplifier has a voltage clamp differential transistor pair coupled to an input differential transistor pair of the operational amplifier. The voltage clamp differential transistor pair limits the output voltage of the operational amplifier by taking over control of the operational amplifier circuits from the input differential transistor pair as the output voltage approaches a clamp voltage value. A reference voltage may be used to set the output voltage at which the input differential transistor pair will be clamped by the voltage clamp differential transistor pair. Below the clamp voltage, operation of the input differential transistor pair will not be affected. At the clamp voltage the input differential transistor pair will no longer control the output of the differential amplifier, rather the voltage clamp differential transistor pair will control the maximum voltage output of the differential amplifier.

Abstract: The present invention is directed to the isolation and cancellation of the offset voltage component typically experienced at the input of sampled-data analog systems. In an exemplary embodiment, offset isolation and cancellation may be performed during normal operation of the sampling circuitry. In an exemplary embodiment, the present invention combines a front-end switching topology with one or more differential integrator stages and a logic algorithm implemented in the differential integrator stages. In operation, the circuitry preferably performs a number of samples for each stage, applies an inversion factor to the samples in accordance with the algorithm and integrates the samples to effect the cancellation of the offset voltage without substantially affecting the sampled input.

Abstract: An electronic amplifier circuit comprising an operational amplifier circuit, such as a two-stage operational amplifier circuit, in tandem with a operational transconductance amplifier. The electronic amplifier circuit has high open-loop gain and high gain-bandwidth while maintaining stability over a wide range of operating parameters.