Realtek Semiconductor Inc.

Fong-Ching Huang

Chao-Cheng Lee

Der-Zheng Liu

Cheng-Chung Hsu

Chih-Yung Shih

Ying-Yao Lin

An apparatus and a method for calibrating IQ mismatch to ensure that an in-phase oscillating signal and a quadrature-phase oscillating signal are orthogonal to each other. The apparatus includes a mixer for mixing the in-phase oscillating signal with the quadrature-phase oscillating signal to generate an output signal, a control module for determining a control signal according to a low-frequency component of the output signal, and a phase adjusting module for adjusting the phase of a specific oscillating signal to ensure that the in-phase oscillating signal and the quadrature-phase oscillating signal are orthogonal to each other. The specific oscillating signal may be the in-phase or the quadrature-phase oscillating signal. The apparatus does not require a digital signal-processing unit to perform complex calculations nor requires additional oscillating sources for calibration. Hence, the circuit design is much simplified, and the consumption of system resources is significantly reduced.

Apparatus and method for calibrating IQ mismatch

A digitally synchronized receiving device and an associated signal processing method are provided. The digitally synchronized receiving device can receive data transmitted by a transmitter. The transmitter and the receiving device belong to a first clock domain and a second clock domain respectively. The receiving device performs synchronization in a digital manner, so as to deal with the problem of the analog solution in prior arts and the synchronization for interference cancellation.

Digitally synchronized receiving device and associated signal processing method

A calibration device for calibrating an ADC comprising: an error estimator for estimating an error of a digital signal outputted from the ADC, the error estimator includes: a digital filter for filtering the digital signal to generate a filtered signal; and a least-mean-square module for performing a least-mean-square operation according to the filtered signal to generate an estimated error; and an error correction module for correcting the digital signal according to the estimated error.

Calibration apparatus for mismatches of time-interleaved analog-to-digital converter

An apparatus and method for synchronizing sampling frequencies of a receiver and a transmitter of a multi-carrier communication system is provided. The receiver includes an estimator for estimating a frequency offset by employing an additional angle rotation of a received signal in frequency domain. The apparatus includes a compensation loop filter for generating a first output in response to a frequency offset compensation, an adder for adding the estimated frequency offset and the first output to generate a second output, and a loop filter for generating frequency offset compensation according to the second output. The method repeatedly applies the apparatus to generate frequency offset compensation, and then feeds it back to an oscillator to compensate the sampling frequency of the receiver. The apparatus and method can also be applied to a communication system with a carrier frequency offset.

Apparatus and method for synchronizing sampling frequency and carrier frequency in a multi-carrier communication system

The present invention provides a method for initialization and stepsize control of a time-domain equalizer (TEQ) in a receiver of a multi-carrier communication system to upgrade the performance of adaptive TEQ algorithms. As to TEQ initialization, the Time-domain Window Mask method generates a modified channel impulse response (CIR) by performing a locate maximum energy algorithm and then applies a time-domain window mask to adjust the modified CIR to obtain an initial value of a target impulse response. Then, a dividing operation is performed on the frequency-domain initial target impulse response and the modified CIR to determine an initial value of the frequency-domain TEQ impulse response. The Head-tail Equalizing method also performs the locate maximum energy algorithm, and the remaining points other than the consecutive points with maximum energy are combined and padded zero to the last few points to generate a modified CIR. The reciprocal of the frequency-domain modified CIR is determined to be an initial value of the frequency-domain TEQ impulse response. The initial value of the frequency-domain target impulse response is determined by multiplying the determined frequency-domain. TEQ impulse response with the frequency-domain of the CIR. The stepsize control method configures the stepsize coefficient as a time-varying coefficient during the whole adapting TEQ algorithm. It is smaller value at an early stage to prevent from divergence and becomes larger at a late adapting stage to prevent from slow convergence.

Method for initialization and stepsize control of time-domain equalizer in multi-carrier communication system

The present invention provides an apparatus and a method for estimating at least one of timing, gain, and offset errors of a time-interleaved ADC. The apparatus has a first ADC, a second ADC, a converter, an estimator, and a compensator. The converter has a Fourier Transform converter and a calculator.

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Hsin-Chu, Taiwan

Fong-Ching Huang