Mstar Semiconductor, Inc.

Wionics Research

Orion Microelectronics Corporation

Sining Zhou

Zaw Soe

Heng-Chih Lin

Chao-Tung Yang

Jackie K Cheng

Shou-Fang Chen

Tony Yang

Tom Baker

Kuangyu Li

Tin-Sing Lam

Fei-Ran Yang

Shoufang Chen

A frequency switching method is used to make switching among a plurality of frequency signal sources each providing a specific frequency range covering multiple bands. The method includes steps of providing a target frequency data; selecting one of the frequency signal sources to output a first clock signal; generating a first frequency data according to the clock signal of the first frequency to compare with the target frequency data; outputting a second clock signal with the highest band of another one of the frequency signal sources possessing a frequency range higher than that of the selected frequency signal source when the target frequency data is greater than the first frequency data; and outputting the second clock signal with the lowest band of the selected frequency signal source when the target frequency data is smaller than the first frequency data.

Frequency switching method

Multistage RF transmitter and receiver circuits may use independently variable RF and IF local oscillators, allowing the RF and IF local oscillator frequencies for a given RF channel to be selected to have a large common factor with respect to the reference oscillator used by the local oscillator circuits, thus allowing the use of small divisor numbers in the local oscillator circuits and reducing phase noise. Independent high-side and low-side RF local oscillators may be provided and selectively used depending on the RF channel to be transmitted or received.

Multiple band RF transmitters and receivers having independently variable RF and IF local oscillators and independent high-side and low-side RF local oscillators

A fixed impedance in parallel with a variable impedance form a high pass filter with a capacitor. An input signal is provided to the capacitor. The value of the variable impedance is controlled in relation to the magnitude of a dynamic DC offset in the input signal to control the corner frequency of the high pass filter, providing a higher corner frequency and more rapid suppression of dynamic DC offset for larger dynamic DC offset magnitudes.

Apparatus and method for dynamic DC offset detection and cancellation using high pass filter with variable impedance and corner frequency

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Irvine, CA, United States of America

Sining Zhou