DIFFERENTIAL INVERSE ALIASING DIGITAL TO ANALOG CONVERTER

• US 20090302899A1
• Filed: 06/10/2008
• Published: 12/10/2009
• Est. Priority Date: 06/10/2008
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Clayton, Munroe C., Tietjen, Byron W.
• Granted Patent: US 8,234,324 B2
• Time in Patent Office: Days
• US Class Current: 327/113
• CPC Class Codes: H03H 17/0621 with input-sampling frequency and output-delivery frequency which differ, e.g. extrapolation; Anti-aliasing
• CPC Class Codes: H03K 7/02 Amplitude modulation, i.e. PAM
• CPC Class Codes: H03M 1/66 Digital/analogue converters H03M1/001 – H03M1/10 take precedence

Abstract

This invention relates to a process for producing a pulsed sampled waveform comprising generating a baseband signal representing the integral of a desired output waveform; sampling and differentiating the baseband signal to produce frequency images of the baseband spectrum at multiples of the sampling rate; employing an analog bandpass filter to pass the spectral image centered at the desired up-conversion frequency band. This invention also relates to an apparatus for creating a high frequency output waveform signal comprising a means for generating a baseband signal representing the integral of a desired output waveform; a means for sampling the baseband signal; a means for generating a time delayed baseband signal by Δt; a means for inverting the delayed baseband signal; a means for summing the inverted the delayed baseband signal with the sampled baseband signal; a means for filtering to pass the high frequency signal.

Claims

1. A method for up-converting a signal frequency comprising;

generating a baseband signal representing the integral of a desired output waveform;

sampling and differentiating the baseband signal to produce frequency images of the baseband spectrum at multiples of the sampling rate; and

filtering the differentiated signal to pass a band of frequencies centered at the desired up-conversion frequency.

2. The method of claim 1, wherein differentiation includes delaying the sampled baseband signal;

inverting the delayed the sampled baseband signal; and

summing the inverted signal and the sampled baseband signal.

3. The method of claim 1, further including filtering the appropriate harmonics generated by sampling and differentiating a baseband signal delayed by a given time differential Δ

t.

4. The method of claim 1, further including narrowing the time delay to reduce the attenuation normally encountered with sin x/x envelope staircase samples.

5. A method for creating a high frequency output waveform signal comprising generating a baseband signal representing the integral of a desired output waveform;

sampling the baseband signal, generating a time delayed baseband signal by a given time differential Δ

t;

inverting the delayed baseband signal;

summing the inverted the delayed baseband signal with the sampled baseband signal;

filtering to pass the high frequency signal.

6. An apparatus for up-converting a signal frequency comprising a means for generating a baseband signal representing the integral of a desired output waveform;

a means for sampling the baseband signal;

a means for generating a time delayed baseband signal by given time differential Δ

t;

a means for inverting the delayed baseband signal;

a means for summing the inverted the delayed baseband signal with the sampled baseband signal;

a means for filtering to pass the high frequency signal.

7. An apparatus for up-converting a signal frequency comprising a digital waveform generator that serves as input to a digital to analog converter producing an analog signal;

a switching means to sample the analog signal to produce a sampled wave containing therein aliases of the analog signal that serve as input to a bandpass filter.

8. The apparatus of claim 7, wherein a sample rate determines the aliases of the analog signal.