Abstract: Electron-beam lithography systems used for transferring images from subfields in a reticle to a wafer. Deflection systems in the electronic lens system are controlled by control systems that include devices to correct misalignment of the electron beams from each of the subfields with the electronic optical axis. In a first embodiment, switches switch between sources to deflect the electron beams to the electronic optical axis and error DACs correct position errors in the sources that are input to the switches. In a second embodiment, the deflection systems deflect the electronic optical axis to coincide with the electron beams from the subfields. In other embodiments, the deflection systems in the electronic lens systems are made insensitive to position errors in deflection control systems by satisfying the condition: G.sub.1 /G.sub.2 =M, where G.sub.1 is the gain of first amplifier amplifying a signal from a DAC which is input to the deflection system deflecting the electron beams from the subfields, G.sub.

Abstract: A full duplex radio having improved properties is obtained by using asymmetric surface acoustic wave (SAW) filters, the filters are composed of series and parallel coupled SAW resonators. Asymmetry is obtained by covering either of the series or parallel resonators of each filter with a dielectric layer to increase the SAW coupling coefficient of the covered resonators relative to the uncovered resonators. The filters are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts of the frequency response are adjacent. Greater pass-bandwidths can be obtained without adverse affect on transmitter and receiver isolation.

Abstract: The ion beam which performs the printing on the resist through the mask is also used to perform the alignment function. Alignment marks are initially provided on the wafer of a material which emits light when an ion beam impinges thereon, such as silicon dioxide. An ion mask, preferably of silicon, is then positioned over the wafer and alignment marks and ions are directed to the alignment marks through the mask. The degree of alignment is determined by the amount of light emitted by the alignment marks since more ions will strike the alignment marks with increased alignment. The emitted light is detected and +X, -X, +Y, -Y and +theta and -theta error signals are provided on a continuous basis for closed loop control of the mask relative to the wafer under proper alignment is achieved.