Abstract: Circuitry (100, 100') for determining actuator position includes four MOS transistors (T1-T4) connected to each side of a bi-directional motor (10). The current flowing through the motor (10) at any given time is proportional to voltages developed across the internal impedances of the transistors (T1-T4). The resulting motor voltages are amplified and high-pass filtered to remove any DC offsets due to the signal amplification. The conditioned motor voltages are then compared to one or more threshold voltages and passed through a one shot circuit (120) to provide detectable pulses for each motor commutation event. Circuitry (106,107) is provided for counting pulses provided by the one shot circuit (120) and, based on a desired motor position, for providing a number of digital control signals to a digital control circuit (104).

Abstract: This invention relates to source-coupled logic (SCL) which is a functional derivative of emitter-coupled logic (ECL). ECL is widely recognized as having the characteristics of high speed (low propagation delay) and low power supply noise generation. The SCL of the prior art succeeds at maintaining and improving the low noise characteristics of this architecture but does not fulfill the promise of high speed that one would expect from a current-mode logic. In addition, it uses a differential form of logic that is not as flexible and easy-to-use as a reference controlled or "single-ended" logic. The SCL disclosed here has the desired high speed properties and maintains the ease of use that is a property of reference controlled ECL. In addition, the reference controlled SCL of this invention provides new capabilities that make it even more flexible than ECL in generating logical switching functions.

Abstract: A programmable high resolution timing system includes a selectable modulus prescaler counter. In one embodiment a high frequency clock is coupled to a prescaler counter which provides an output signal every predetermined number of clock pulses. The prescaler is coupled to a period counter which provides a period signal after a predetermined number of prescaler output signal pulses. The prescaler and period counter are coupled to a memory which stores data corresponding to the selected modulus of the prescaler and the number of counts by which the period counter output signal is to be delayed. The period resolution is thus made substantially equal to the resolution of the high frequency clock by varying the prescaler modulus at programmable intervals.

Abstract: A two-terminal optical sensor circuit comprising a light-emitting diode, phototransistor, amplifier, and current source electrically and optically coupled so as to approximate an ideal switch in one quadrant of its V-I characteristic. A remote object is detected when it moves into the optical path between the light source and sensor.