Digital to analog conversion method and apparatus
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsPatrik Eriksson, Peter Petersson
Life of this patent
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Abstract
A digital-to-analog circuit arrangement that can be used, for example, in radio transmitters, includes a Digital-to-Analog Converter (DAC) whose output is connected directly to a mixer. A periodic signal is also provided to the mixer. The frequency of the periodic signal provided to the mixer, is an integer multiple of half the update rate frequency of the DAC. In an embodiment of the invention, the frequency of the periodic signal provided to the mixer, is half the update rate frequency of the DAC. An intermediate frequency (IF) filter can be provided. downstream of the mixer.
Claims22
An apparatus comprising:
- a digital-to-analog converter (DAC) that receives a digital input signal and outputs a corresponding analog signal;
- a local oscillator that outputs a local oscillator signal at a frequency equal to an integer multiple of one-half of an update rate of the DAC;
- and
- a mixer that receives the output analog signal directly from the DAC, receives the output local oscillator signal, and mixes the output analog signal with the output local oscillator signal.
A method for processing a digital signal, comprising the steps of:
- converting the digital signal to a first analog signal based on the digital signal and a first periodic signal having a first frequency;
- and
- mixing the first analog signal with a second periodic signal to form a second analog signal, said second periodic signal having a second frequency that is an integer multiple of one-half the first frequency of the first periodic signal.
A radio transmitter comprising:
- means for receiving a digital signal encoded with information to be transmitted;
- a digital-to-analog converter (DAC) that receives the digital signal and outputs a corresponding analog signal based on the input signal and an update rate of the DAC;
- a local oscillator that outputs a local oscillator signal at a frequency equal to an integer multiple of one-half of the update rate of the DAC;
- a mixer configured to:
- receive the output analog signal from the DAC;
- receive the output local oscillator signal;
- mix the output analog signal with the output local oscillator signal;
- and
- output a mixed analog signal;
- and
- a power amplifier that receives the output mixed analog signal from the mixer and amplifies the mixed analog signal for transmission.
Dependencies are inferred from the claim text.