Seagate Technology Incorporated

Lam Resarch Corporation

Max T Artusy

Karl Arnold Belser

Neil M Benjamin

Seyed Jafar Jafarian-Tehrani

Stephen J Hrinya

A micro-motor position controller utilizes a ratiometric position sensor that operates independent of any reference voltage sources. A first capacitor and a second capacitor in a micro-motor are connected in series and form one section of a capacitive bridge. The other section of the bridge is ground. A first sinusoidal voltage is created at the top of the capacitive bridge and a second sinusoidal voltage that is 180 degrees out of phase from the first sinusoidal voltage is created at the bottom of the bridge. The motor is moved and the capacitance values of the first and second capacitors are changed until, ultimately, there is no voltage present on the armature of the motor. The voltage level present at the armature is measured relative to AC ground, and is used as an error signal to control the position of the motor.

Precision micro-motor position controller

A system and method is disclosed for correcting gain and offset errors in a signal amplifier for a position sensitive detector. The present invention eliminates the need to perform division for normalization by holding constant a signal proportional to the sum of the two signals generated by the position sensitive detector. First the two signals generated by the position sensitive detector are pulse-width modulated with a common variable duty cycle clock, and then the resulting modulated signals are low-pass filtered to extract the DC component. The duty cycle is varied so that the sum of the two DC components is held constant. In the preferred embodiment, the means for varying the duty cycle are closed-loop feedback and open-loop feed forward. The closed-loop feedback gives long term accuracy and the open-loop feed forward gives rapid settling time. Once the sum of the DC components of the modulated signals is held constant, the individual DC components of the modulated signals are normalized and may be used for servo or other applications.

System and method of correcting gain and offset error in a signal amplifier for a position sensitive detector

An r.f. excited vacuum plasma processor has a workpiece held in place by a monopolar or bipolar electrostatic chuck having an electrode that develops peak r.f. voltages over a wide amplitude range. A chuck DC power supply source is connected to the chuck. An r.f. peak detecting circuit coupled with the electrode is part of a circuit for controlling the DC voltage applied by the chuck power supply to the chuck. The control circuit supplies an unamplified replica of a DC voltage derived by the peak detecting circuit to the chuck DC power supply source via a DC circuit including only passive elements so the level of the DC voltage applied to the chuck varies in response to variations in the peak amplitude of the r.f. voltage. The peak detector includes at least several series connected diodes having electrodes polarized in the same direction or two stacks of series connected diodes. In one of the stacks, the diode electrodes are polarized in one direction and in the other stack the diode electrodes are polarized in the other direction. The diodes of the peak detecting circuit are arranged so the DC bias voltage supplied to the chuck and the peak value of the r.f. voltage developed at the electrode have the same order of magnitude.

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Saratoga, CA, United States of America

Max T Artusy