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Regarding AD9361 LO frequency offset correction

Question asked by nandak on Oct 20, 2015
Latest reply on Oct 26, 2015 by tlili

We are doing LTE Femto testing with RF board based on AD9361 . We require a few clarifications wrt the programming of this chip . The ref manual we are using is the RF and BBPLL Synthesiser User Manual, 2.4 ver , 2010 .

We are programming the EARFCN for Band 3 (1842.5MHZ) , The SPI programming part is given below,


// Setup Synthesizer FREF of 38.4MHz (2x19.2)

SPIWrite              27A,4A  // Set VCO Output level[3:0]

SPIWrite              279,C0   // Set Init ALC Value[3:0] and VCO Varactor[3:0]

SPIWrite              282,0D  // Set VCO Bias Tcf[1:0] and VCO Bias Ref[2:0]

SPIWrite              278,70   // Set VCO Cal Offset[3:0]

SPIWrite              285,00   // Set VCO Cal Ref Tcf[2:0]

SPIWrite              291,09   // Set VCO Varactor Reference[3:0]

SPIWrite              290,70   // Set VCO Varactor Ref Tcf[2:0] and VCO Varactor Offset[3:0]

SPIWrite              27B,8E   // Set Synth Loop Filter charge pump current (Icp)

SPIWrite              27E,C3   // Set Synth Loop Filter C2 and C1

SPIWrite              27F,EF   // Set Synth Loop Filter  R1 and C3

SPIWrite              280,0B   // Set Synth Loop Filter R3

 

SPIWrite              233,00   // Write Rx Synth Fractional Freq Word[7:0]

SPIWrite              234,00   // Write Rx Synth Fractional Freq Word[15:8]

SPIWrite              235,04   // Write Rx Synth Fractional Freq Word[22:16]

SPIWrite              232,00   // Write Rx Synth Integer Freq Word[10:8]

SPIWrite              231,B6   // Write Rx Synth Integer Freq Word[7:0]

SPIWrite              005,11   // Set LO divider setting

SPIWrite              273,7D  // Write Tx Synth Fractional Freq Word[7:0]

SPIWrite              274,AA  // Write Tx Synth Fractional Freq Word[15:8]

SPIWrite              275,76   // Write Tx Synth Fractional Freq Word[22:16]

SPIWrite              272,00   // Write Tx Synth Integer Freq Word[10:8]

SPIWrite              271,BF   // Write Tx Synth Integer Freq Word[7:0] (starts VCO cal)

SPIWrite              005,11   // Set LO divider setting

SPIRead               247         // Check RX RF PLL lock status (0x247[1]==1 is locked)

SPIRead               287         // Check TX RF PLL lock status (0x287[1]==1 is locked)


The programmed frequency o/p shows an offset of 500 KHz .Pl. guide us on

how to offset this by programming

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