Patent ID: 8238860

Claim:
A circuit for tuning a second order intercept point (IP 2 ) of a mixer to minimize second order intermodulation distortion (IMD 2 ) in a receiver of a transceiver, comprising: means for generating a normally-transmitted two-level PN DSSS signal; means for producing a specially-generated four-level PN DSSS signal whose squared version thereof has a low correlation with the normally-transmitted two-level PN DSSS signal; means for squaring the specially-generated four-level PN DSSS signal; means for transmitting the specially-generated four-level PN DSSS signal; means for attenuating the transmitted signal; means for receiving the attenuated transmitted signal; means for causing IMD 2 to occur as a result of receiving the received attenuated transmitted signal, thereby producing a two-level PN DSSS signal; means for correlating codewords of the two-level PN DSSS signal produced by the IMD 2 with codewords of the squared version of the specially-generated four-level PN DSSS signal produced by the means for squaring; means for changing an operating parameter of the mixer to change an IP 2 thereof; means for determining composite power in chips of each correlated codeword at a plurality of operating parameters; and means for determining the operating parameter of the mixer that produces a maximum composite power, thereby tuning the IP 2 of a mixer to cause minimal IMD 2 in the receiver.