Tritech Microelectronics, Ltd

David Ho Poh

Liusheng Liu

In the present invention is described a forward feed sigma delta modulator of higher order having automatic saturation detection and recovery. The modulator is separated into two parts which are connected together when there is no saturation, and disconnected when saturation is detected and recovery takes place. The first part contains an integrator and input output circuitry to allow continuous operation of the modulator. The second part contains additional integrators to provider for a higher order modulator and the saturation detector. The modulator can be constructed of single ended or differential switched capacitor technology, and there is a digital saturation detection scheme.

Sigma delta modulator with automatic saturation detection and recovery

A multilevel capacitor structure compatible with CMOS processing for use in switched capacitor circuits is disclosed. The capacitor structure has an associated parasitic capacitor which is placed in such a way so as to minimize the impact on the performance of a the switched capacitor circuit. The parasitic capacitor is formed between a first plate of the shielded capacitor and a diffusion well within a substrate. The diffusion well is connected to a quiet voltage reference source to isolate the shielded capacitor from noise present on the substrate. The shielded capacitor has a first plate that is fabricated from a first conductive material such as polycrystalline silicon or polycide, a second plate fabricated from a second conductive material such as a first level of metal on an integrated circuit, and a third capacitor plate fabricated from a second level of metal of an integrated circuit. The first plate and the third plate are connected to give a total capacitance given by the sum of capacitances between the first plate and second plate and between the second plate and third plate.

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Singapore, Singapore

David Ho Poh