Hello,
I try to get a clear tone from LMX2571 at 440MHz (440,460,480 MHz as well) using TCXO 40MHz and there are some side spikes with the ~1.7kHz offset (tone is clear at e.g. 441MHz). It is not the Integer boundary problem. When I use TCXO 39MHz, the problem shows up at e.g. 429 MHz.
Could you review synthesizer's settings, please? Maybe you could see something wrong.
Register 0: 0x00000083
Register 1: 0x00017A5B
Register 2: 0x00029080
Register 3: 0x00031200
Register 4: 0x00042018
Register 5: 0x00050103
Register 6: 0x00060688
Register 7: 0x00070080
Register 8: 0x0008001F
Register 9: 0x00090000
Register 10: 0x000A0000
Register 11: 0x000B0000
Register 12: 0x000C0000
Register 13: 0x000D0000
Register 14: 0x000E0000
Register 15: 0x000F0000
Register 16: 0x00100000
Register 33: 0x00210000
Register 34: 0x00221100
Register 35: 0x00231904
Register 39: 0x002711FB
Register 40: 0x0028081C
Register 41: 0x00290808
Register 42: 0x002A0210
Register 46: 0x002E001A
Register 47: 0x002F6000
Register 53: 0x00357806
Register 58: 0x003A8C00
Register 60: 0x003CA000
F1F2_SEL: 0
Enable Port TX: 1
Pwr OUTBUF Port TX: 31
(CP_IDN + CP_IUP) * CP_GAIN: ( 8 + 8 ) * 0 [CP_Gain= 1] CP = 2500 uA
FSK_EN, FSK_MODE_SEL, FSK_LEVEL, FSK_DEV_SEL: 0 0 0 0
Loop Filter Order: 2, Loop Filter: R3=0, R4=0
Calculated Parameters TX(F1):
Freq Out: 440000000
Synthesizer's Freq: 440000000
Ref Freq: 39999845
OSC div R: 2 3_*8_1
Freq PDF: 106666253
Output CHDIV: 12
N prescaler: 2
Fvco: 5280000000
Integer N: 24
Frac: 6000768
Denominator: 8000000
Thank you,
Alex
