Abstract: A motion sensor (10) includes a micromachined sensing structure and a number of capacitive electrodes (20) disposed about a periphery thereof. The sensing structure includes a ring (14) supported above a substrate (12) so as to have an axis of rotation normal to the substrate (12), and a number of springs (16) attached to a post (18) positioned at the center of the ring (14). Certain diametrically opposed ones of the capacitive electrodes (20) are configured as drive electrodes (20a), and other diametrically opposed ones of the capacitive electrodes (20), positioned 90 degrees relative to the corresponding drive electrodes (20a) are configured as sense electrodes (20b). Signals produced at the opposed sense electrodes (20b) are conditioned and coupled to a common input of an amplifier circuit (64,70).

Abstract: A signal amplifying circuit (24) includes level shifting input circuits (D1-D4) permitting input common-mode voltages (VIN1 and VIN2) of an amplifier and fault detection circuit (50) to vary between preset limits. The sense amplifier circuit (24) includes a DC offset buffer circuit (52) operable to receive an analog DC offset compensation signal and provide this signal to an input of the amplifier and fault detection circuit (50). The buffered DC offset compensation signal provided to the amplifier and fault detection circuit (50) is operable to reduce an aggregate DC offset voltage attributable to signal amplifying circuit (24) to a desired DC offset level. The amplifier and fault detection circuit (50) also includes a fault detection function whereby an output (VSENSE) of the amplifier circuit (50) is forced to a predetermined output state if either, or both, of the inputs (VIN1 and VIN2) of the sense amplifier circuit (24) are unconnected; i.e., floating.

Abstract: A DC offset compensation circuit (34) for compensating for a DC offset voltage of a signal amplifier (24) includes a first sample and hold circuit (40) having an input receiving an amplifier output signal (VOUT2) and an output supplying the sampled and held output signal (VOUT2) to a non-inverting input of a comparator 42. A first digital-to-analog (D/A) circuit (46) is responsive to a number of digital input signals to produce an analog DC target signal at an output (VD) thereof. The analog DC target signal is provided to an input of a second sample and hold circuit (50) having an output supplying the sampled and held analog DC target signal to an inverting input of the comparator 42. The output of the comparator 42 is provided to an offset cancellation control circuit (56) including a state machine (66) and a counter circuit (68) operable to modify a count value (OFFDAC) thereof depending upon statuses of a number of input control signals (CLK1, CLK2, STRT, STP) and the comparator output signal (CO).

Abstract: A CMOS analog divider/multiplier/ratiometry circuit that provides a ratiometric output of two or more inputs, where the output is insensitive to process parameters and temperature variations effecting the circuit. The analog divider/multiplier/ratiometry circuit includes a multiplier portion made up of six FET devices. The six FET devices are electrically connected together so that first and second current outputs from the multiplier portion are insensitive to process parameter and temperature variations effecting the circuit. A first input current is applied to a gate terminal of one of the FET devices and a second input current is applied to a gate terminal of the FET devices in the multiplier portion of the circuit. The first and second input currents are based on currents generated by first and second linear voltage-to-current converter input circuits that are responsive to first and second input voltage, respectively, whose ratio or product is to be determined at the output of the circuit.

Abstract: A motion sensor having a micromachine sensing element and electrodes formed on a silicon chip. The sensing element includes a ring supported above a substrate so as to have an axis of rotation normal to the substrate. Surrounding the ring is at least one pair of diametrically-opposed electrode structures. The sensing ring and electrode structures are configured to include interdigitized members whose relative placement to each other enables at least partial cancellation of the effect of differential thermal expansion of the ring and electrodes. As a result, the performance of the motion sensor is, to first order, insensitive to temperature variation. The sensor further includes circuitry for creating and detecting an electrostatic force between the interdigitized members of the sensing ring and electrode structures.

Abstract: A cross-coupled latch circuit that is a one-time programmable latch that allows volatile temporary writes to the latch prior to permanent programming of the latch. The latch circuit includes first and second programmable FET devices that include poly-poly capacitators in series with the gate terminal of each device. A pair of PMOS FET devices combine with the programmable devices to make up the latch. The latch circuit includes other FET devices that are switched on and off depending on whether the latch is being permanently programmed, temporarily written to, or reset. A NAND gate is provided such that a logical high output on the NAND gate allows the first programmable device to be temporarily programmed with a logical one and permanently programmed with a logical zero. A NOR gate is provided such that a logical high on the NOR gate allows the second programmable device to be temporarily programmed with a logical zero and permanently programmed with a logical one.