Digital down-converter
AssigneeSamsung Electronics Co., Ltd.
InventorKishi Takahiko
Life of this patent
Estimating the term…
Abstract
A digital down-converter having a low spurious level and a high frequency precision without increasing power consumption of a local oscillator. A first mixer receives, as a first IF input signal, a digital signal obtained by sampling a received signal with an RF signal or an IF signal, and converts the first IF input signal to a second IF signal using the first local oscillator. A digital filter suppresses an outband signal of the second IF signal provided from the first mixer. A second mixer converts an output of the digital filter to a detection process frequency using the second local oscillator. An available frequency step of the first local oscillator is larger than an available frequency step of the second local oscillator.
Claims9
A digital down-converter comprising:
- first and second local oscillators for outputting a sine wave and a cosine wave, the first and second local oscillators being direct digital synthesizers wherein a phase operation word length of the direct digital synthesizer corresponding to the first local oscillator is identical to an input word length of a sine/cosine wave table for converting phase data to sine and cosine waves;
- a first mixer for receiving, as a first IF (Intermediate Frequency) input signal, a digital signal obtained by sampling a received signal with an RF (Radio Frequency) signal or a separate IF signal, and converting the first IF input signal to a second IF signal using the first local oscillator;
- a digital filter for suppressing an outband signal of the second IF signal provided from the first mixer;
- and
- a second mixer for converting an output of the digital filter to a detection process frequency using the second local oscillator;
- wherein an available frequency step of the first local oscillator is larger than an available frequency step of the second local oscillator.
A digital down-converter comprising:
- first and second local oscillators;
- a first mixer for receiving, as a first IF (Intermediate Frequency) input signal, a digital signal obtained by sampling a received signal with an RF (Radio Frequency) signal or a separate IF signal, and converting the first IF input signal to a second IF signal using the first local oscillator;
- a digital filter for suppressing an outband signal of the second IF signal provided from the first mixer;
- and
- a second mixer for converting an output of the digital filter to a detection process frequency using the second local oscillator;
- wherein an available frequency step of the first local oscillator is larger than an available frequency step of the second local oscillator and
- a bandwidth of the digital filter is equal to a communication channel bandwidth plus an output frequency step of the first local oscillator.
A digital down-converter comprising:
- a first local oscillator having a rough frequency step and a low spurious level, said spurious level corresponding to an output word length;
- a second local oscillator having a fine frequency step and an inconsistent spurious characteristic;
- a first mixer for receiving a digital signal and converting the digital signal to a second IF signal using the first local oscillator, the digital signal being a first IF (Intermediate Frequency) input signal and being obtained by sampling a received signal with one of an RF (Radio Frequency) signal and a separate IF signal;
- a digital filter for suppressing an outband signal of the second IF signal provided from the first mixer;
- and
- a second mixer for converting an output of the digital filter to a detection process frequency using the second local oscillator;
- wherein an available frequency step of the first local oscillator is larger than an available frequency step of the second local oscillator.
Dependencies are inferred from the claim text.