Abstract: A method and an apparatus are provided for filtering a substantially square wave signal. At least a portion of the substantially square wave signal is applied to a first filter adapted to pass a range of frequencies adjacent the fundamental frequency and produce a first filtered signal. At least a portion of the substantially square wave signal is also applied to a plurality of second filters, where each of the second plurality of filters is adapted to pass a range of frequencies adjacent an odd harmonic component of the fundamental frequency and produce a second filtered signal. The first signal and the plurality of second filtered signals are combined to produce a representation of a square wave signal having a frequency substantially corresponding to the fundamental frequency.

Abstract: A method and an apparatus are provided for filtering a substantially square wave signal. At least a portion of the substantially square wave signal is applied to a first filter adapted to pass a range of frequencies adjacent the fundamental frequency and produce a first filtered signal. At least a portion of the substantially square wave signal is also applied to a plurality of second filters, where each of the second plurality of filters is adapted to pass a range of frequencies adjacent an odd harmonic component of the fundamental frequency and produce a second filtered signal. The first signal and the plurality of second filtered signals are combined to produce a representation of a square wave signal having a frequency substantially corresponding to the fundamental frequency.

Abstract: An analog-to-digital converter (ADC) includes a dither signal generator configured to add an analog dither signal to the analog input signal of the ADC prior to digitization (i.e., quantization). The amplitude of the dither signal is selected based upon the power levels of one or more carriers present in the bandwidth for which the ADC is designed to operate. Addition of the dither signal to the input signal in the analog domain reduces quantization noise such as conversion spurs that result from non-linearities in the ADC transfer function.

Abstract: An input device for inputting data into a computer or a video game is provided. The input device includes two keyballs mounted to a base. The keyballs may be swiveled relative to the base. Each keyball includes a plurality of switches for activation by the finger tips and thumb tips of a typist. By moving the keyballs and pressing the switches, the typist can enter data in a manner which mimics a conventional typing method. During operation, the typist's hands need not leave the keyballs. Therefore, the input device can reduce strains, and the likelihood of injuries such as carpal tunnel syndrome, to the wrists of the typist.