(19)

(11)

EP 0 476 124 A1

(12)

(43) Date of publication: 25.03.1992 Bulletin 1992/13 (21) Application number: 91907928.0 (22) Date of filing: 28.03.1991

(51) International Patent Classification (IPC):  H03K 17/ 687( . ) (86) International application number: PCT/US1991/002194 (87) International publication number: WO 1991/015055 (03.10.1991 Gazette 1991/23)

(84) Designated Contracting States: DE FR GB IT (30) Priority: 28.03.1990 US 19900500450 (71) Applicant: VARIAN ASSOCIATES, INC. Palo Alto, California 94304-1030 (US)	(72) Inventor: EINSENBERG, John, A. Los Altos, CA 94022 (US) (74) Representative: Cline, Roger Ledlie  EDWARD EVANS & CO. Chancery House 53-64 Chancery Lane London WC2A 1SD London WC2A 1SD (GB)