Phase Alignment Among Multiple Transmitters

Abstract

Systems and methods for phase alignment among multiple transmitters are described. In some embodiments, a method may include creating a loop between an RF transmitter and an RF receiver; measuring a first DC signal on the I and Q paths of the RF receiver without inserting a DC signal in the I and Q paths of the RF transmitter; measuring a second DC signal on the I and Q paths of the RF receiver while inserting a non-zero DC signal in the I and Q paths of the RF transmitter; and calculating a relative phase difference between the RF transmitter and the RF receiver using the first and second DC signals.

1 . A method, comprising:
 creating a loop between an RF transmitter and an RF receiver;   measuring a first DC signal on the I and Q paths of the RF receiver without inserting a DC signal in the I and Q paths of the RF transmitter;   measuring a second DC signal on the I and Q paths of the RF receiver while inserting a non-zero DC signal in the I and Q paths of the RF transmitter; and   calculating a relative phase difference between the RF transmitter and the RF receiver using the first and second DC signals.   
     
     
         2 . The method of  claim 1 , further comprising, prior to measuring the first or second DC signals, calibrating the loop. 
     
     
         3 . The method of  claim 2 , wherein calibrating the loop includes performing a loop DC cancellation procedure. 
     
     
         4 . The method of  claim 2 , wherein calibrating the loop includes performing an I/Q imbalance compensation procedure. 
     
     
         5 . The method of  claim 1 , wherein the non-zero DC signal corresponds to a gain index. 
     
     
         6 . The method of  claim 1 , further comprising repeating the measuring and calculating operations for another gain index. 
     
     
         7 . The method of  claim 1 , further comprising storing a relative phase difference for each different gain index. 
     
     
         8 . An electronic circuit, comprising:
 a processor; and   a memory coupled to the controller, the memory having program instructions stored thereon that, upon execution by the processor, cause the processor to:
 create a loop between an RF transmitter and an RF receiver; 
 measure a first DC signal on the I and Q paths of the RF receiver without inserting a DC signal in the I and Q paths of the RF transmitter; 
 measure a second DC signal on the I and Q paths of the RF receiver while inserting a non-zero DC signal in the I and Q paths of the RF transmitter; and 
 calculate a relative phase difference between the RF transmitter and the RF receiver using the first and second DC signals. 
   
     
     
         9 . The electronic circuit of  claim 8 , wherein the program instructions, upon execution, further cause the processor to, prior to measuring the first or second DC signals, calibrate the loop at least in part by performing a loop DC cancellation procedure. 
     
     
         10 . The electronic circuit of  claim 8 , wherein the program instructions, upon execution, further cause the processor to, prior to measuring the first or second DC signals, calibrate the loop at least in part by performing an I/Q imbalance compensation procedure. 
     
     
         11 . The electronic circuit of  claim 8 , wherein the non-zero DC signal corresponds to a gain index, and wherein the program instructions, upon execution, further cause the processor to repeat the measuring and calculating operations for other gain indexes, and to store a relative phase difference for each different gain index.