Abstract: In general, the present invention provides a low cost mechanism for reducing the settling time and/or improving the phase noise performance of a frequency synthesizer in a mobile station. In one embodiment, the present invention eliminates the need for using two transmit offset synthesizers in a mobile station which must be able to operate on two different frequency bands characterized by different transmit-receive (TX-RX) channel separation. According to the present invention, one or both of the transmit offset synthesizers may be eliminated by deriving an appropriate transmit offset signal from an auxiliary synthesizer in the mobile station through a relatively simple and inexpensive frequency scaling circuit (e.g., frequency divider or multiplier), and by using a fast settling main channel synthesizer to hop between two different frequencies when the mobile station is switching between transmitting and receiving, respectively.

Abstract: A dual band transceiver for operating in a first lower frequency band such as the band allocated to cellular systems, and in a second higher frequency band such as the band allocated to personal communication services (PCS) systems. In a representative embodiment, the dual band transceiver comprises a main voltage controlled oscillator (VCO) for generating a local oscillator (LO) signal; an offset VCO for generating an offset frequency (OF) signal; a first mixer for combining the LO signal with the OF signal to produce a first transmit signal; a modulator for modulating the first transmit signal with the data signal to produce a first data modulated transmit signal; and a second mixer for combining the first data modulated transmit signal with the LO signal to produce a second data modulated signal. The main VCO and the offset VCO can be programmed such that the first data modulated transmit signal is in the first band and the second data modulated transmit signal is in the second band.