Abstract: A circuit is disclosed that compensates for the non-linearity of a current mode real pole producing circuit used to generate poles and zeros in complex filter circuits. The non-linearity of the prior art is compensated by driving one end of the primary pole producing capacitor with a signal derived from the drain current and fed back so as to counteract the non-linearity factors.

Abstract: A circuit is disclosed that compensates for the non-linearity of a current mode real pole producing circuit used to generate poles and zeros in complex filter circuits. The non-linearity of the prior art is compensated by driving one end of the primary pole producing capacitor with a signal derived from the drain current and fed back so as to counteract the non-linearity factors.

Abstract: A system for acquiring environmental information measurements. The 5 system (100) utilize a sensor, (205) a front-end circuit, (310) a loop filter (315), a switch controller (206), and a reduced-order loop control circuit to provide reliable data measurements while providing robust system behavior. The system further includes a sensor simulator (330) for simulating the operation of the sensor (205) and testing the operation of the front-end circuit (310) and the loop filter (315).

Abstract: A method and apparatus for measuring and compensating for stray capacitance of a micro-machined sensor of an accelerometer system is disclosed. Stray capacitance differences between a top plate and a sensing element and between a bottom plate and the sensing element degrade accelerometer performance if not compensated for. Measurement of stray capacitance difference is achieved by operating the accelerometer in two calibration phases and measuring the steady-state output voltage in each of the two phases. In calibration phase 1, no force is applied to the sensor during clock intervals 1-4. In calibration phase 2, a dummy force up is applied and then a dummy force down is applied during those intervals 1-4. The difference in the output voltage of the two calibration phases is representative of the difference in stray capacitance of the sensor. Capacitance is added to the top or bottom plates in an amount proportional to the measured stray capacitance.

Abstract: Apparatus for measuring a characteristic of motion and methods for its manufacture are disclosed in which a sensor structure includes a support structure, and a mass suspended from such support structure by a spring connecting arrangement and electrical devices for measuring displacement of the mass which results from a force applied to the support structure. An apparatus is provided where the mechanical spring constant of the connecting arrangement of the sensor structure is provided to be a high value representative of a strong, stiff spring which resists breaking due to high forces applied to it, and where an electric spring constant is provided to yield a small effective sensor spring constant K.sub.eff =K.sub.m -K.sub.e. Methods are also provided to manufacturing the apparatus by specifying the mechanical spring constant and providing an electric spring constant which will yield a desired effective spring constant which produces a desired characteristic of the sensor structure.

Abstract: Apparatus for identifying a particulate substance in suspension based on the radiation scattering behavior of the substance, which apparatus includes a source of a collimated beam of substantially monochromatic radiation which is linearly polarized along a first polarization axis, at least two modulators disposed in the path of the polarized beam for effecting polarization modulation of the polarized beam about respective dynamic axes at respective modulation frequencies, a sample of the substance being held in the path of the beam between the modulators so that radiation is scattered by the substance in a scattering plane, a polarizing device disposed in the scattering plane for passing that portion of the scattered radiation which is parallel to a second polarization axis, and a signal processing device for producing an indication of the intensity of the radiation emerging from the polarizing device at frequencies corresponding to selected elements of a Mueller matrix which characterizes the scattering prop