Method and apparatus for analog-to-digital conversion
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsPeter Magnus Petersson, Mats Johansson
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Abstract
The present invention eliminates the need for an anti-aliasing filter in a receiver that employs an analog-to-digital converter. By maintaining a predetermined relationship between a local oscillator frequency and the sampling frequency of the analog-to-digital converter, aliasing that would normally occur in the desired pass band is avoided. More specifically, the frequency of the periodic signal provided to the mixer is an integer multiple of half the sampling rate of the analog-to-digital converter. In a preferred, non-limiting example embodiment, the sampling rate of the analog-to-digital converter FADC and the frequency of the local oscillator FLO are related by the following: FLO=n * FADC/2, where n is any positive integer.
Claims34
An apparatus comprising:
- a mixer for mixing a received signal and a local oscillator signal and generating an analog, frequency converted signal, and
- an analog-to-digital converter for converting the analog, frequency-converted signal into a corresponding digital signal,
- wherein a frequency of the local oscillator signal is an integer multiple of half of a sampling rate of the analog-to-digital converter.
A radio receiver comprising:
- an antenna;
- a front end for processing a radio frequency signal received via the antenna;
- a mixer for mixing a received signal from the front end and a local oscillator signal for generating an analog, frequency-converted signal;
- an analog-to-digital converter for converting the analog, frequency-converted signal into a corresponding digital signal;
- and
- digital processing circuitry for processing the digital signal,
- wherein a frequency of the local oscillator signal is an integer multiple of half of a sampling rate of the analog-to-digital converter.
An apparatus comprising:
- a mixer for mixing a received signal and a local oscillator signal for generating an analog, frequency-converted signal, and
- an analog-to-digital converter for converting the analog, frequency-converted signal into a corresponding digital signal,
- wherein the analog, frequency-converted signal is connected directly to an input of the analog-to-digital converter.
An apparatus comprising:
- a mixer for mixing a received signal and a local oscillator signal to generate an analog, frequency-converted signal, and
- an analog-to-digital converter for converting the analog, frequency-converted signal into a corresponding digital signal,
- wherein a frequency of the local oscillator signal is related to a sampling rate of the analog-to-digital converter to prevent aliasing that would otherwise result from the mixing and converting.
A method comprising:
- receiving an analog signal;
- mixing the received signal and a local oscillator signal to generate an analog, frequency-converted signal, and
- converting the analog, frequency-converted signal into a corresponding digital signal using a sampling rate signal,
- wherein a frequency of the local oscillator signal is an integer multiple of half of a frequency of the sampling rate signal.
Dependencies are inferred from the claim text.