The Research Of Single-chip Zero-IF Wireless Transmitter Carrier Leakage Cancellation Technology

Silicon germanium (SiGe) bipolar CMOS(BiCMOS)has been the dominant processtechnology for RF transceivers of cellular Communication systems.However, in recentyears, there is increasing interest to implement RF transceivers using CMOS technologydriven by the demand for high-volume and low-cost solutions.Direct-conversion transmitter offers an attractive solution due to its inherentcompactness and ease of integration compared to heterodyne architecture, and it has beenwidely used in integrated transceiver designs to achieve low cost and low powerconsumption.Hower,a major drawback of direct conversion transmitter is carrier leakage.Itis one of the major challenges in the design direct conversion transmitter.In this paper,first describe the overview of the development of wirelesscommunication and make a brief introduction about WCDMA system.Then the zero-IFtransceiver is described and the advantages and disadvantages of zero-IF transceiver aresummarized.And then describe the reason choose the zero-IF transmitter in thisarticle.After analysis the transmitter system parameters,decribe a highly linear,high outputpower,carrier leakage suppression CMOS direct conversion transmitter for wide band codedivision multiple access (WCDMA).In the CDMA standard,due to the power control range,the carrier leakage willseriously affect the performance of the transmitter in low power output,it is necessary tosuppress the carrier leakage.In addition,the excess carrier leakage can also affect theaccuracy of power control requirements and limitations of channel capacity.Circuittechniques to suppress carrier leakage therefore hold the key to a high integration levelthrough the direct conversion architecture.In this article,we will make a study of carrierleakage of direct conversion transmitter.On this basis,we will presents a calibrationtechnique that enables the direct conversion architecture to meet WCDMAspecifications.Detected by using a power detector,adjust the baseband DC offset voltageby calibration circuit achieve the suppression of carrier leakage.An auto-calibrationalgorithm is also implemented the carrier leakage power at the quadrature modulator output can be minimized.