Frequency translator using a cordic phase rotator

A technology of frequency converter and phase accumulator, which is applied in the direction of power oscillator, amplitude-to-angle modulation conversion, modulation transfer, etc., and can solve problems such as oscillator not working normally, oscillator inaccuracy, and complexity

Inactive Publication Date: 2004-01-14
思凯比特兹公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The local oscillator is often inaccurate
Although the inaccurate quantity can be determined by calibration, tuning the oscillator to compensate for this inaccurate quantity is complex
Additionally, applications using the oscillator may not function properly if the oscillator is not properly tuned

Method used

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  • Frequency translator using a cordic phase rotator
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  • Frequency translator using a cordic phase rotator

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Embodiment Construction

[0022] The present invention optimizes hardware frequency translation by using only shift-add operations for frequency translation. Additionally, the present invention overcomes the problem of RF frequency synthesizers having wide strides. The RF frequency synthesizer can be used to obtain close to the desired frequency, and the present invention can add any fine tuning required to produce a desired frequency. For example, the present invention allows tuning to 1 hertz (Hz) steps, which is difficult to achieve using an RF frequency synthesizer. Likewise, the invention can be used to compensate for offsets in local oscillator frequency. This can be accomplished by calibrating the local oscillator to determine the offset, and then using the present invention to convert the frequency produced by the oscillator to compensate for this offset.

[0023] The invention can also be used as a frequency modulator. For example, with FSK modulation, the frequency shift applied to a carri...

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Abstract

A frequency translator uses a CORDIC phase rotator coupled to a phase accumulator to translate an input signal in frequency. The CORDIC phase rotator performs required phase angle rotations of input vectors using only shift and add operations. Thus, the frequency translator can be readily implemented in hardware. Higher precision arithmetic is used in the CORDIC phase rotator operations than the input vectors contain. To avoid truncation error at the output of the CORDIC phase rotator, stochastic rounding is employed. A dither signal is added to avoid errors due to nonlinear operation of D / A converters, where D / A conversion of the frequency translated signal is required.

Description

[0001] This application claims the benefit of US Provisional Application No. 60 / 223,972, filed August 9,2000. technical field [0002] The present invention is mainly concerned with frequency conversion. More particularly, the present invention relates to frequency translation in a communication system that is facilitated to be implemented in digital hardware. The invention further relates to the use of frequency converters in a number of applications including upconversion of baseband signals to RF (Radio Frequency) frequencies for transmission over modems, correction of local oscillator offset and FSK (Frequency Shift Keying) modulation. Background technique [0003] There are numerous application requirements for frequency translation. For example, transmitting a baseband signal through a modem requires up-conversion of the baseband signal to an appropriate transmission frequency. As another example, in wireless modem applications, suitable transmission frequencies are...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03D7/00H03C3/40H04L27/12
CPCH03C3/40
Inventor 马克·C·苏立文
Owner 思凯比特兹公司
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