Differential inverse aliasing digital to analog converter

• US 8,234,324 B2
• Filed: 06/10/2008
• Issued: 07/31/2012
• Est. Priority Date: 06/10/2008
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Tietjen, Byron W., Clayton, Munroe C.
• Primary Examiner(s): Malzahn, David H
• Application Number:
  US12/136,452
• Publication Number:
  US 20090302899A1
• Time in Patent Office: 1,512 Days
• Field of Search: None
• US Class Current: 708/300
• 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 baseband signal; and

summing the inverted signal and the sampled baseband signal.

3. The method of claim 1, wherein the step of generating a baseband signal representing the integral of a desired output waveform comprises integrating a baseband signal.

4. 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 version of the sampled baseband signal;

inverting the delayed baseband signal; and

summing the inverted baseband signal with the sampled baseband signal.

5. The method of claim 4, further comprising the step of filtering the summed signal.

6. The method of claim 4, wherein the step of generating a baseband signal representing the integral of a desired output waveform comprises integrating a baseband signal.

7. 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 version of the baseband signal;

a means for inverting the delayed baseband signal;

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

a means for filtering the summed signal.

8. The apparatus of claim 7, wherein the means for generating a baseband signal comprises a wave generator.

9. The apparatus of claim 7, wherein the means for sampling the baseband signal comprises a sample and hold circuit.

10. The apparatus of claim 7, wherein the means for sampling the baseband signal is responsive to a switching signal received from a pulse generator.

11. The apparatus of claim 7, wherein the means for summing the inverted baseband signal and the sampled baseband signal comprises a summing amplifier.

12. The apparatus of claim 7, wherein the means for filtering the summed signal comprises a bandpass filter.

13. An apparatus for up-converting a signal frequency comprising:

a digital waveform generator;

a digital to analog converter responsive to the output of the digital waveform generator for producing an analog signal;

a switching means for sampling the analog signal to produce a sampled wave containing therein aliases of the analog signal, and

a bandpass filter for filtering the sampled wave.

14. The apparatus of claim 13, wherein a sample rate of the switching means determines the aliases of the analog signal.