TESTING TONE FREE CLOSE LOOP NOTCH FREQUENCY CALIBRATION FOR DELTA-SIGMA DATA CONVERTERS
First Claim
1. A receiver module for a front-end circuit of a radio, said receiver module comprising:
- an analog-to-digital converter (ADC) that converts analog signals to digital signals;
a Fast-Fourier transform (FFT) circuit responsive to the digital signals from the ADC and converting the digital signals to frequency spectrum signals;
a moving average circuit responsive to the frequency spectrum signals from the FFT circuit, said moving average circuit smoothing out the frequency spectrum signals by applying a moving average to the frequency spectrum signals;
a differentiator circuit responsive to the smoothed frequency spectrum signals from the moving average circuit and differentiating the frequency spectrum signals to make the signals linear;
a minimum finding circuit responsive to the differentiated frequency spectrum signals from the differentiator circuit and converting the differentiated frequency spectrum signals into a positive value for frequencies above a notch frequency in the differentiated signals and a negative value for frequencies below the notch frequency in the differentiated signals; and
an adaptive control circuit responsive to the positive and negative values from the minimum finding circuit, said adaptive control circuit comparing a transition between the negative values and the positive values to a desired frequency value to identify a difference therebetween, and providing a calibration signal to the ADC if the difference is greater than a predetermined threshold value.
1 Assignment
0 Petitions
Accused Products
Abstract
A cellular radio architecture that includes a receiver module having a delta-sigma modulator that converts analog signals to digital signals and a Fast-Fourier transform (FFT) circuit that converts the digital signals to frequency spectrum signals. The architecture also includes a moving average circuit that smoothes out the frequency spectrum signals by applying a moving average to the signals. The architecture further includes a differentiator circuit that differentiates the frequency spectrum signals to make the signals linear, and a minimum finding circuit that converts the differentiated frequency spectrum signals into positive values for frequencies above a notch frequency in the differentiated signals and negative values for frequencies below the notch frequency in the differentiated signals. A transition between the positive and negative values is compared to a desired notch frequency value, and if the difference is greater than a predetermined threshold, an adaptive control circuit calibrates the modulator.
-
Citations
18 Claims
-
1. A receiver module for a front-end circuit of a radio, said receiver module comprising:
-
an analog-to-digital converter (ADC) that converts analog signals to digital signals; a Fast-Fourier transform (FFT) circuit responsive to the digital signals from the ADC and converting the digital signals to frequency spectrum signals; a moving average circuit responsive to the frequency spectrum signals from the FFT circuit, said moving average circuit smoothing out the frequency spectrum signals by applying a moving average to the frequency spectrum signals; a differentiator circuit responsive to the smoothed frequency spectrum signals from the moving average circuit and differentiating the frequency spectrum signals to make the signals linear; a minimum finding circuit responsive to the differentiated frequency spectrum signals from the differentiator circuit and converting the differentiated frequency spectrum signals into a positive value for frequencies above a notch frequency in the differentiated signals and a negative value for frequencies below the notch frequency in the differentiated signals; and an adaptive control circuit responsive to the positive and negative values from the minimum finding circuit, said adaptive control circuit comparing a transition between the negative values and the positive values to a desired frequency value to identify a difference therebetween, and providing a calibration signal to the ADC if the difference is greater than a predetermined threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A receiver module for a front-end circuit of a radio, said receiver module comprising:
-
a delta-sigma modulator that converts analog signals to digital signals; and a digital signal processor (DSP) that converts the digital signals to frequency spectrum signals, identifies a notch frequency in the frequency spectrum signals, compares the notch frequency to a predetermined desired frequency, and calibrates the delta-sigma modulator if the difference between the notch frequency and the desired frequency is greater than a predetermined threshold, wherein the DSP includes a Fast-Fourier transform (FFT) circuit that employs a Fast-Fourier transform to convert the digital signals to the frequency spectrum signals and a moving average circuit that smoothes out the frequency spectrum signals by applying a moving average to the frequency spectrum signals. - View Dependent Claims (12, 13, 14, 15)
-
-
10. (canceled)
-
11. (canceled)
-
16. A method for calibrating an analog-to-digital converter (ADC) in a receiver module in a front-end circuit for a radio, said method comprising:
-
converting analog signals to digital signals in the ADC; Fast-Fourier transforming the digital signals to frequency spectrum signals; smoothing out the frequency spectrum signals by applying a moving average to the frequency spectrum signals; differentiating the smooth frequency spectrum signals to make the signals linear; converting the differentiated frequency spectrum signals into a positive value for frequencies above a notch frequency in the differentiated signals and a negative value for frequencies below the notch frequency in the differentiated signals; comparing a transition between the positive and negative values to a desired notch frequency to provide a difference signal; determining whether the difference signal is greater than a predetermined threshold; and calibrating the ADC if the difference signal is greater than the threshold. - View Dependent Claims (17, 18)
-
Specification