Abstract: A multi-band high gain mixer and quadrature signal generator allows a receiver system to receive signals at multiple frequency bands without requiring significant hardware duplication. A single mixer directly receives any of three communication frequency bands such as Universal Mobile Telecommunication System (UMTS), Personal Communication Services (PCS), Digital Communication System (DCS), and Japan and US W-CDMA 800 bands without amplification. A Serial-Parallel Interface selectably forwards RF signals within the receiver's frequency channels to the mixer for demodulation into in-phase (I) and quadrature (Q) signals at a common IF output from the multi-mode receiver. Significant power and cost advantages are attained by elimination of duplicate mixers and amplifier stages.

Abstract: A VCO circuit including a VCO, a voltage supply and a control circuit. The VCO has a supply voltage input and a gain that changes with its supply voltage. The voltage supply has an adjust input and an output coupled to the supply voltage input of the VCO. The voltage supply adjusts the voltage level of its output in response to changes of the adjust input. The control circuit has a first adjust output coupled to the adjust input of the voltage supply to adjust the gain of the VCO. The VCO may include a frequency range adjust input controlled by the control circuit so that the gain of the VCO is adjusted when the frequency range is changed. For a multi-band VCO, the gain is adjusted for different frequency bands to maintain a relatively constant gain for each frequency band.

Abstract: A transmitter is provided that corrects for both static and dynamic offsets to minimize carrier feedthrough. A feedback loop permits correction to be performed during normal operation of the transmitter, rather than during a calibration sequence in which the inputs are zeroed. The transmitter includes an adder that subtracts a correction signal from an input signal to produce a corrected signal. A filter filters the corrected signal and a modulator modulates the filtered signal to produce an RF signal. The feedback loop includes a mixer that converts the RF signal to baseband, an A/D converter that converts the baseband signal to a digital signal, which is provided to an FFT, a matched filter that filters the signal from the FFT, a Maximum Seeking Frequency Estimator that determines the maximum signal, and a gain that compensates for the feedback loop and produces the correction signal.