The proliferation and popularity of mobile radio and telephony applications has led to market demand for communication systems with low cost, low power, and small form-factor radio-frequency (RF) transceivers. As a result, recent research has focused on providing monolithic transceivers using low-cost complementary metal-oxide semiconductor (CMOS) technology. One aspect of research efforts has focused on providing an RF transceiver within a single integrated circuit (IC). The integration of transceiver circuits is not a trivial problem, as it must take into account the requirements of the transceiver's circuitry and the communication standards governing the transceiver's operation. From the perspective of the transceiver's circuitry, RF transceivers typically include sensitive components susceptible to noise and interference with one another and with external sources. Integrating the transceiver's circuitry into one integrated circuit may exacerbate interference among the various blocks of the transceiver's circuitry. Moreover, communication standards governing RF transceiver operation outline a set of requirements for noise, inter-modulation, blocking performance, output power, and spectral emission of the transceiver.
Unfortunately, no known technique for addressing all of the above issues in high-performance RF receivers or transceivers, for example, RF transceivers used in cellular and telephony applications, has been developed. A need therefore exists for techniques of partitioning and integrating RF receivers or transceivers that would provide low-cost, low form-factor RF transceivers for high-performance applications, for example, in cellular handsets.
A further aspect of RF receivers and transceivers relates to providing high-performance signal processing functions in an integrated form. Typical conventional receivers and transceivers rely on baseband processor circuitries to implement various signal processing functions, such as channelization filtering. Some baseband processor circuitries, however, do not contain their own channelization filtering. Furthermore, the system designer may choose to not implement channelization filtering in a baseband processor circuitry in order to, for example, reduce performance requirements for data converter circuitries present in the receiver or transceiver. The migration of the signal processing functions to the baseband processor circuitry may also result in its increased complexity. Moreover, front-end analog circuitry contributes DC offsets that impact the processing of the desired signal. A further need therefore exists for RF apparatus that provide high performance signal processing functions to implement functions ranging from reduction or cancellation of DC offsets to signal processing within the RF apparatus signal path, such as channelization filtering.
USPTO Backgrounds
USPTO Backgrounds