The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 18, 1988
Filed:
Jun. 01, 1987
James Henden, Sunnyvale, CA (US);
Gentron Corporation, Milwaukee, WI (US);
Quantel International Inc., Santa Clara, CA (US);
Abstract
A power MOSFET linear amplifier includes a plurality of paralleled MOSFETS having a gate-to-source resistor to ensure simultaneous turn-on and sharing of the load current. An arc lamp is connected in series with a 400 volt power supply and a variable ballast element in the form of the power MOSFET linear amplifier. The linear amplifier includes four similar modules. Each module is a hybrid circuit constructed with eight MOSFETs connected in parallel. Each MOSFET includes a similar gate-to-source resistor in addition to an appropriate gate resistor and source resistor. Under operating load current conditions, the gate-to-source resistors are laser trimmed to establish precise equalized current sharing in response to the specified operating input voltages. The module is set with the gate voltage slightly above the operating threshold voltage range of the MOSFET. The modules then operate with the essentially simultaneous turn-on of all MOSFETs and in a reliable balancing of current between the several MOSFET devices. The modules are fabricated with a common heat sink and an appropriate packaging for rapid dissipation of the heat, to thereby maintain the necessary low operating temperature which is essential to reliable operation of the MOSFET devices.