Browse Prior Art Database

Temperature Control of Sense Resistors for Electron Beam Yoke Drivers

IP.com Disclosure Number: IPCOM000053109D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Ho, CT: AUTHOR [+3]

Abstract

This article describes a control system which is effective in maintaining constant temperature of the current-sensing resistor in a deflection amplifier despite changes in deflection current and ambient temperature.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Temperature Control of Sense Resistors for Electron Beam Yoke Drivers

This article describes a control system which is effective in maintaining constant temperature of the current-sensing resistor in a deflection amplifier despite changes in deflection current and ambient temperature.

E-beam lithography systems generally are used to write large field sizes as well as to provide fast response with high accuracy. These requirements in turn require that yoke drivers deliver high yoke current (in the range of 10 amps) with high accuracy and speed. Consequently, a large amount of power must be dissipated in the current sensing resistor used to develop the feedback voltage in the driver circuit shown in Fig. 1, thus causing its temperature and resistance to vary. Since the deflection current is inversely proportional to the resistance of the current-sense resistor, the deflection magnitude also varies and makes it important to minimize the resistance variations. Resistance variations may be kept to a minimum by the use of a resistor with a low temperature coefficient (TC), as well as by controlling the resistor temperature.

The thermodynamics of the heat sink (Fig. 2) must be considered to provide a temperature-controlled system that is fast enough to respond to deflection power changes. The required response is achieved by placing the current-sense resistor and the heater resistor in close proximity. Both heater resistor and current-sense resistor are metal film resistors fabricated on the same ceramic substrate. The current sense resistor is maintained at a constant temperature b...