Abstract: A data converter system provides an output signal having reduced spurious tones by confining an input signal to a specified frequency band and over-sampling so that the converted input signal “straddles” or “avoids” spurious tones. The spurious tones may then be filtered away, providing an output signal having a much cleaner spurious free dynamic range than a conventional data converter. For example, in one embodiment, an interleaved data converter system converts an input signal that is confined to the second Nyquist zone of one of the interleaved data converters into an interleaved signal, and then filters the interleaved signal with a filter having a pass-band that transmits the converted input frequencies and a stop-band that attenuates the spurious tones. The resulting output signal has a bandwidth that is the same as could be achieved using a single data converter, but is not impaired by interleave images or certain distortion products.

Abstract: A data converter system provides an output signal having reduced spurious tones by confining an input signal to a specified frequency band and over-sampling so that the converted input signal “straddles” or “avoids” spurious tones. The spurious tones may then be filtered away, providing an output signal having a much cleaner spurious free dynamic range than a conventional data converter. For example, in one embodiment, an interleaved data converter system converts an input signal that is confined to the second Nyquist zone of one of the interleaved data converters into an interleaved signal, and then filters the interleaved signal with a filter having a pass-band that transmits the converted input frequencies and a stop-band that attenuates the spurious tones. The resulting output signal has a bandwidth that is the same as could be achieved using a single data converter, but is not impaired by interleave images or certain distortion products.

Abstract: An autoranging apparatus and method for an analog-to-digital converter (ADC) which uses a proposed gain detector including a peak of absolute detector and a quantizer to determine a proposed gain, and a amplifier gain setting rule processor in parallel with an anti-aliasing (AA) filter. The rule processor generates a current gain from inputs including the current gain, proposed gain, and a resolution bandwidth (RBW) value. The current gain is used to set a variable amplifier before the signal is sampled & held, and then converted to a digital word via the ADC. A variable bandpass filter can additionally be used before the AA filter to produce a pre-filtered signal. The pre-filtered signal would similarly be processed by the proposed gain detector. The resulting digital word is scaled down again through values stored in a look-up table. The look-up table is generated via a calibration routine which determines with certain precision the variable gain levels for the particular amplifier device used.

Abstract: A swept synthesizer signal source provides a digital synchronization signal for accurate internal synchronization of events and for external synchronization of data taking and other operations to predetermined frequencies generated by an oscillator during a sweep. The digital synchronication signal includes a predetermined number of digital pulses, regardless of the sweep time. A ramp voltage which controls the oscillator is corrected during a calibration period to sweep between predetermined limits, thereby insuring that the ramp voltage is synchronized to the digital synchronication signal. The slope of the frequency versus time sweep is also corrected to further improve accuracy. A power level correction technique insures precision power leveling regardless of the sweep range. A table of correction/frequency pairs is entered into the instrument, and an interpolation algorithm is employed to determine corrections at frequencies corresponding to each synchronization pulse.