Sirific Wireless Corporation

Lawrence Wong

Tajinder Manku

Gareth Pryce Weale

Chris Snyder

Yang Ling

This patent describes a method and system which overcomes the LO-leakage problem during modulation and demodulation, common to direct conversion and similar RF transmitters and receivers. This problem is solved using a virtual local oscillator (VLO&#x2122;) signal which emulates mixing with a local oscillators (LO) signal. The VLO signal is constructed using complementary mixing signals that suppress mixing power in the bandwidth of the input signal, and within the bandwidth of the output frequency. Specifically, mixing is done in two or more stages, using time-varying mixing signals &#x3c6;and &#x3c6;which satisfy the following criteria: &#x3c6;*&#x3c6;having significant power at the frequency of the LO being emulated, one of &#x3c6;and &#x3c6;having minimal power around the frequency of the output signal y(t), and the other of &#x3c6;and &#x3c6;having minimal power around the center frequency, f, of the input signal x(t).

Method and apparatus for up-and-down-conversion of radio frequency (RF) signals

This patent describes a method and system which overcomes the LO-leakage problem of direct conversion and similar RF transmitters and receivers. To solve this problem a virtual LO&#x2122; signal is generated which emulates mixing with a local oscillator (LO) signal. However, the virtual local oscillator (VLO) signal is constructed using signals that do not contain a significant amount of power (or no power at all) at the wanted output RF frequency, so there is no LO component to leak to the output. The invention also does not require sophisticated filters or large capacitors as other designs in the art, so it is fully integratable.

Method and apparatus for up-and down-conversion of radio frequency (RF) signals

This patent describes a method of removing the LO-leakage and 1/f noise problems associated with direct conversion RF receivers and other demodulators. In order to solve this problem a virtual LO&#x2122; signal is generated within the RF signal path which is tuned to the incoming RF signal. The virtual local oscillator (VLO) signal is constructed using signals that do not contain a significant amount of power (or no power at all) at the LO frequency. Any errors in generating the virtual LO signal are minimized using a closed loop correction scheme.

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Markham, Canada

Lawrence Wong