Other Parts Discussed in Thread: USB2ANY, ,
Tool/software:
Hi,
Recently I've designed a custom PCB containing 3 LMX2820 ICs, in order to simultaneously generate 3 output frequencies: 325, 650 and 1300 MHz. The reference signal (162.5 MH 7 dBm) is applied from external signal generator and is distributed via power splitter to 3 OSCin_P pins. I also have used TICS pro software with LMX2820EVM and USB2ANY in order to get a PLL set up (VCO, Dividers, Multipliers, Charge pump current, output power levels, etc.). Exported Register Maps for 123 registers have been implemented in the C code for the microcontroller, that drives LMX2820 via 3 independent SPI buses. My custom Hardware was missing couple things:
1. MUTE pin wasn't shorted to GND - I had to do it on PCBA. I also have set a PINMUTE_Pol active High.
2. RFOUTA_P and _N output signals requires AC Coupling 100nF capacitors - I forgot to add them to the design. I have cut the copper tracks and ripped of a piece of soldermask covering the traces and assembled required capacitors in series.
After performing a fix No.1 I was able to lock all the 3 PLL at the specified frequencies - proven using a spectrum analyzer.
RFOUTA_P and _N output signals are converted into single ended signal via balun TCM2-43X+ RF transformer (3dB instertion loss).
The main problem is the power level of the output signals (output signals, i.e. signals at the SMA output) 325 MHz -17.5 dBm, 650 MHz -20.1 dBm and 1300 MHz -23.2 dBm. I expect output signals to have power level between 6 and 7 dBm (bracket power has value 7 in TICS PRO). These output power levels were the same before and after performing a fix No. 2. Afterwards I have also removed C26 and C27 0.5 pF capacitors to see if power levels of the output signals will improve. Unfortunately the power output levels were still the same.
I have performed a simple test: AC coupling capacitors from fix No.2 have been mounted vertically in order to open the RF transformer circuit. A 100 ohm termination resistor has been assembled to the capacitors from the other side. I've measured voltage on the resistor using wide band differential probe connected to spectrum analyzer. Results: -26 dBm Peak at 1300 MHz. This test ensured me, that the transformer circuit is not the problem and low power level must come from PLL IC's.
I see couple possible reasons: a) I have set up wrong register maps. b) PLL IC's may be damaged because of missing AC coupling capacitors during first few tests before ading fix No. 2.
I send the register maps for 325, 650 and 1300 MHz in the attachement - IT Support please answer if you find any problem with register values. I also send a screen containing LMX2820 circuit - Maybe a problem hides somewhere in the schematic.
uint8_t tx_325_buffer[369] = {
0x7A, 0x00, 0x00, // R122 0x7A0000
0x79, 0x00, 0x00, // R121 0x790000
0x78, 0x00, 0x00, // R120 0x780000
0x77, 0x00, 0x00, // R119 0x770000
0x76, 0x00, 0x00, // R118 0x760000
0x75, 0x00, 0x00, // R117 0x750000
0x74, 0x00, 0x00, // R116 0x740000
0x73, 0x00, 0x00, // R115 0x730000
0x72, 0x00, 0x00, // R114 0x720000
0x71, 0x00, 0x00, // R113 0x710000
0x70, 0xFF, 0xFF, // R112 0x70FFFF
0x6F, 0x00, 0x00, // R111 0x6F0000
0x6E, 0x00, 0x1F, // R110 0x6E001F
0x6D, 0x00, 0x00, // R109 0x6D0000
0x6C, 0x00, 0x00, // R108 0x6C0000
0x6B, 0x00, 0x00, // R107 0x6B0000
0x6A, 0x00, 0x00, // R106 0x6A0000
0x69, 0x00, 0x0A, // R105 0x69000A
0x68, 0x00, 0x14, // R104 0x680014
0x67, 0x00, 0x14, // R103 0x670014
0x66, 0x00, 0x28, // R102 0x660028
0x65, 0x03, 0xE8, // R101 0x6503E8
0x64, 0x05, 0x33, // R100 0x640533
0x63, 0x19, 0xB9, // R99 0x6319B9
0x62, 0x1C, 0x80, // R98 0x621C80
0x61, 0x00, 0x00, // R97 0x610000
0x60, 0x17, 0xF8, // R96 0x6017F8
0x5F, 0x00, 0x00, // R95 0x5F0000
0x5E, 0x00, 0x00, // R94 0x5E0000
0x5D, 0x10, 0x00, // R93 0x5D1000
0x5C, 0x00, 0x00, // R92 0x5C0000
0x5B, 0x00, 0x00, // R91 0x5B0000
0x5A, 0x00, 0x00, // R90 0x5A0000
0x59, 0x00, 0x00, // R89 0x590000
0x58, 0x03, 0xFF, // R88 0x5803FF
0x57, 0xFF, 0x00, // R87 0x57FF00
0x56, 0x00, 0x40, // R86 0x560040
0x55, 0x00, 0x00, // R85 0x550000
0x54, 0x00, 0x40, // R84 0x540040
0x53, 0x0F, 0x00, // R83 0x530F00
0x52, 0x00, 0x00, // R82 0x520000
0x51, 0x00, 0x00, // R81 0x510000
0x50, 0x01, 0xC0, // R80 0x5001C0
0x4F, 0x01, 0x0E, // R79 0x4F010E
0x4E, 0x00, 0x00, // R78 0x4E0000
0x4D, 0x06, 0x08, // R77 0x4D0608
0x4C, 0x00, 0x00, // R76 0x4C0000
0x4B, 0x00, 0x00, // R75 0x4B0000
0x4A, 0x00, 0x00, // R74 0x4A0000
0x49, 0x00, 0x00, // R73 0x490000
0x48, 0x00, 0x00, // R72 0x480000
0x47, 0x00, 0x00, // R71 0x470000
0x46, 0x00, 0x0E, // R70 0x46000E
0x45, 0x00, 0x11, // R69 0x450011
0x44, 0x00, 0x20, // R68 0x440020
0x43, 0x10, 0x00, // R67 0x431000
0x42, 0x00, 0x3F, // R66 0x42003F
0x41, 0x00, 0x00, // R65 0x410000
0x40, 0x00, 0x80, // R64 0x400080
0x3F, 0xC3, 0x50, // R63 0x3FC350
0x3E, 0x00, 0x00, // R62 0x3E0000
0x3D, 0x03, 0xE8, // R61 0x3D03E8
0x3C, 0x01, 0xF4, // R60 0x3C01F4
0x3B, 0x13, 0x88, // R59 0x3B1388
0x3A, 0x00, 0x00, // R58 0x3A0000
0x39, 0x00, 0x01, // R57 0x390001
0x38, 0x00, 0x01, // R56 0x380001
0x37, 0x00, 0x02, // R55 0x370002
0x36, 0x00, 0x00, // R54 0x360000
0x35, 0x00, 0x00, // R53 0x350000
0x34, 0x00, 0x00, // R52 0x340000
0x33, 0x20, 0x3F, // R51 0x33203F
0x32, 0x00, 0x80, // R50 0x320080
0x31, 0x00, 0x00, // R49 0x310000
0x30, 0x41, 0x80, // R48 0x304180
0x2F, 0x03, 0x00, // R47 0x2F0300
0x2E, 0x03, 0x00, // R46 0x2E0300
0x2D, 0x00, 0x00, // R45 0x2D0000
0x2C, 0x00, 0x00, // R44 0x2C0000
0x2B, 0x00, 0x00, // R43 0x2B0000
0x2A, 0x00, 0x00, // R42 0x2A0000
0x29, 0x00, 0x00, // R41 0x290000
0x28, 0x00, 0x00, // R40 0x280000
0x27, 0x03, 0xE8, // R39 0x2703E8
0x26, 0x00, 0x00, // R38 0x260000
0x25, 0x05, 0x00, // R37 0x250500
0x24, 0x00, 0x40, // R36 0x240040
0x23, 0x31, 0x00, // R35 0x233100
0x22, 0x00, 0x10, // R34 0x220010
0x21, 0x00, 0x00, // R33 0x210000
0x20, 0x11, 0x01, // R32 0x201101
0x1F, 0x04, 0x01, // R31 0x1F0401
0x1E, 0xB1, 0x8C, // R30 0x1EB18C
0x1D, 0x31, 0x8C, // R29 0x1D318C
0x1C, 0x06, 0x39, // R28 0x1C0639
0x1B, 0x80, 0x01, // R27 0x1B8001
0x1A, 0x0D, 0xB0, // R26 0x1A0DB0
0x19, 0x06, 0x24, // R25 0x190624
0x18, 0x0E, 0x34, // R24 0x180E34
0x17, 0x11, 0x02, // R23 0x171102
0x16, 0xE2, 0xBF, // R22 0x16E2BF
0x15, 0x1C, 0x64, // R21 0x151C64
0x14, 0x27, 0x2C, // R20 0x14272C
0x13, 0x21, 0x20, // R19 0x132120
0x12, 0x00, 0x00, // R18 0x120000
0x11, 0x15, 0xC0, // R17 0x1115C0
0x10, 0x17, 0x1C, // R16 0x10171C
0x0F, 0x20, 0x01, // R15 0x0F2001
0x0E, 0x30, 0x01, // R14 0x0E3001
0x0D, 0x00, 0x38, // R13 0x0D0038
0x0C, 0x04, 0x08, // R12 0x0C0408
0x0B, 0x06, 0x02, // R11 0x0B0602
0x0A, 0x00, 0x00, // R10 0x0A0000
0x09, 0x00, 0x05, // R9 0x090005
0x08, 0xC8, 0x02, // R8 0x08C802
0x07, 0x00, 0x00, // R7 0x070000
0x06, 0x0A, 0x43, // R6 0x060A43
0x05, 0x00, 0x32, // R5 0x050032
0x04, 0x42, 0x04, // R4 0x044204
0x03, 0x00, 0x41, // R3 0x030041
0x02, 0x81, 0xF4, // R2 0x0281F4
0x01, 0x57, 0xA0, // R1 0x0157A0
0x00, 0x64, 0x70 // R0 0x006470
};
uint8_t tx_650_buffer[369] = {
0x7A, 0x00, 0x00, // R122
0x79, 0x00, 0x00, // R121
0x78, 0x00, 0x00, // R120
0x77, 0x00, 0x00, // R119
0x76, 0x00, 0x00, // R118
0x75, 0x00, 0x00, // R117
0x74, 0x00, 0x00, // R116
0x73, 0x00, 0x00, // R115
0x72, 0x00, 0x00, // R114
0x71, 0x00, 0x00, // R113
0x70, 0xFF, 0xFF, // R112
0x6F, 0x00, 0x00, // R111
0x6E, 0x00, 0x1F, // R110
0x6D, 0x00, 0x00, // R109
0x6C, 0x00, 0x00, // R108
0x6B, 0x00, 0x00, // R107
0x6A, 0x00, 0x00, // R106
0x69, 0x00, 0x0A, // R105
0x68, 0x00, 0x14, // R104
0x67, 0x00, 0x14, // R103
0x66, 0x00, 0x28, // R102
0x65, 0x03, 0xE8, // R101
0x64, 0x05, 0x33, // R100
0x63, 0x19, 0xB9, // R99
0x62, 0x1C, 0x80, // R98
0x61, 0x00, 0x00, // R97
0x60, 0x17, 0xF8, // R96
0x5F, 0x00, 0x00, // R95
0x5E, 0x00, 0x00, // R94
0x5D, 0x10, 0x00, // R93
0x5C, 0x00, 0x00, // R92
0x5B, 0x00, 0x00, // R91
0x5A, 0x00, 0x00, // R90
0x59, 0x00, 0x00, // R89
0x58, 0x03, 0xFF, // R88
0x57, 0xFF, 0x00, // R87
0x56, 0x00, 0x40, // R86
0x55, 0x00, 0x00, // R85
0x54, 0x00, 0x40, // R84
0x53, 0x0F, 0x00, // R83
0x52, 0x00, 0x00, // R82
0x51, 0x00, 0x00, // R81
0x50, 0x01, 0xC0, // R80
0x4F, 0x01, 0x0E, // R79
0x4E, 0x00, 0x00, // R78
0x4D, 0x06, 0x08, // R77
0x4C, 0x00, 0x00, // R76
0x4B, 0x00, 0x00, // R75
0x4A, 0x00, 0x00, // R74
0x49, 0x00, 0x00, // R73
0x48, 0x00, 0x00, // R72
0x47, 0x00, 0x00, // R71
0x46, 0x00, 0x0E, // R70
0x45, 0x00, 0x11, // R69
0x44, 0x00, 0x20, // R68
0x43, 0x10, 0x00, // R67
0x42, 0x00, 0x3F, // R66
0x41, 0x00, 0x00, // R65
0x40, 0x00, 0x80, // R64
0x3F, 0xC3, 0x50, // R63
0x3E, 0x00, 0x00, // R62
0x3D, 0x03, 0xE8, // R61
0x3C, 0x01, 0xF4, // R60
0x3B, 0x13, 0x88, // R59
0x3A, 0x00, 0x00, // R58
0x39, 0x00, 0x01, // R57
0x38, 0x00, 0x01, // R56
0x37, 0x00, 0x02, // R55
0x36, 0x00, 0x00, // R54
0x35, 0x00, 0x00, // R53
0x34, 0x00, 0x00, // R52
0x33, 0x20, 0x3F, // R51
0x32, 0x00, 0x80, // R50
0x31, 0x00, 0x00, // R49
0x30, 0x41, 0x80, // R48
0x2F, 0x03, 0x00, // R47
0x2E, 0x03, 0x00, // R46
0x2D, 0x00, 0x00, // R45
0x2C, 0x00, 0x00, // R44
0x2B, 0x00, 0x00, // R43
0x2A, 0x00, 0x00, // R42
0x29, 0x00, 0x00, // R41
0x28, 0x00, 0x00, // R40
0x27, 0x03, 0xE8, // R39
0x26, 0x00, 0x00, // R38
0x25, 0x05, 0x00, // R37
0x24, 0x00, 0x40, // R36
0x23, 0x31, 0x00, // R35
0x22, 0x00, 0x10, // R34
0x21, 0x00, 0x00, // R33
0x20, 0x10, 0xC1, // R32
0x1F, 0x04, 0x01, // R31
0x1E, 0xB1, 0x8C, // R30
0x1D, 0x31, 0x8C, // R29
0x1C, 0x06, 0x39, // R28
0x1B, 0x80, 0x01, // R27
0x1A, 0x0D, 0xB0, // R26
0x19, 0x06, 0x24, // R25
0x18, 0x0E, 0x34, // R24
0x17, 0x11, 0x02, // R23
0x16, 0xE2, 0xBF, // R22
0x15, 0x1C, 0x64, // R21
0x14, 0x27, 0x2C, // R20
0x13, 0x21, 0x20, // R19
0x12, 0x00, 0x00, // R18
0x11, 0x15, 0xC0, // R17
0x10, 0x17, 0x1C, // R16
0x0F, 0x20, 0x01, // R15
0x0E, 0x30, 0x01, // R14
0x0D, 0x00, 0x38, // R13
0x0C, 0x04, 0x08, // R12
0x0B, 0x06, 0x02, // R11
0x0A, 0x00, 0x00, // R10
0x09, 0x00, 0x05, // R9
0x08, 0xC8, 0x02, // R8
0x07, 0x00, 0x00, // R7
0x06, 0x0A, 0x43, // R6
0x05, 0x00, 0x32, // R5
0x04, 0x42, 0x04, // R4
0x03, 0x00, 0x41, // R3
0x02, 0x81, 0xF4, // R2
0x01, 0x57, 0xA0, // R1
0x00, 0x64, 0x70 // R0
};
uint8_t tx_1300_buffer[369] = {
0x7A, 0x00, 0x00, // R122
0x79, 0x00, 0x00, // R121
0x78, 0x00, 0x00, // R120
0x77, 0x00, 0x00, // R119
0x76, 0x00, 0x00, // R118
0x75, 0x00, 0x00, // R117
0x74, 0x00, 0x00, // R116
0x73, 0x00, 0x00, // R115
0x72, 0x00, 0x00, // R114
0x71, 0x00, 0x00, // R113
0x70, 0xFF, 0xFF, // R112
0x6F, 0x00, 0x00, // R111
0x6E, 0x00, 0x1F, // R110
0x6D, 0x00, 0x00, // R109
0x6C, 0x00, 0x00, // R108
0x6B, 0x00, 0x00, // R107
0x6A, 0x00, 0x00, // R106
0x69, 0x00, 0x0A, // R105
0x68, 0x00, 0x14, // R104
0x67, 0x00, 0x14, // R103
0x66, 0x00, 0x28, // R102
0x65, 0x03, 0xE8, // R101
0x64, 0x05, 0x33, // R100
0x63, 0x19, 0xB9, // R99
0x62, 0x1C, 0x80, // R98
0x61, 0x00, 0x00, // R97
0x60, 0x17, 0xF8, // R96
0x5F, 0x00, 0x00, // R95
0x5E, 0x00, 0x00, // R94
0x5D, 0x10, 0x00, // R93
0x5C, 0x00, 0x00, // R92
0x5B, 0x00, 0x00, // R91
0x5A, 0x00, 0x00, // R90
0x59, 0x00, 0x00, // R89
0x58, 0x03, 0xFF, // R88
0x57, 0xFF, 0x00, // R87
0x56, 0x00, 0x40, // R86
0x55, 0x00, 0x00, // R85
0x54, 0x00, 0x40, // R84
0x53, 0x0F, 0x00, // R83
0x52, 0x00, 0x00, // R82
0x51, 0x00, 0x00, // R81
0x50, 0x01, 0xC0, // R80
0x4F, 0x01, 0x0E, // R79
0x4E, 0x00, 0x00, // R78
0x4D, 0x06, 0x08, // R77
0x4C, 0x00, 0x00, // R76
0x4B, 0x00, 0x00, // R75
0x4A, 0x00, 0x00, // R74
0x49, 0x00, 0x00, // R73
0x48, 0x00, 0x00, // R72
0x47, 0x00, 0x00, // R71
0x46, 0x00, 0x0E, // R70
0x45, 0x00, 0x11, // R69
0x44, 0x00, 0x20, // R68
0x43, 0x10, 0x00, // R67
0x42, 0x00, 0x3F, // R66
0x41, 0x00, 0x00, // R65
0x40, 0x00, 0x80, // R64
0x3F, 0xC3, 0x50, // R63
0x3E, 0x00, 0x00, // R62
0x3D, 0x03, 0xE8, // R61
0x3C, 0x01, 0xF4, // R60
0x3B, 0x13, 0x88, // R59
0x3A, 0x00, 0x00, // R58
0x39, 0x00, 0x01, // R57
0x38, 0x00, 0x01, // R56
0x37, 0x00, 0x02, // R55
0x36, 0x00, 0x00, // R54
0x35, 0x00, 0x00, // R53
0x34, 0x00, 0x00, // R52
0x33, 0x20, 0x3F, // R51
0x32, 0x00, 0x80, // R50
0x31, 0x00, 0x00, // R49
0x30, 0x41, 0x80, // R48
0x2F, 0x03, 0x00, // R47
0x2E, 0x03, 0x00, // R46
0x2D, 0x00, 0x00, // R45
0x2C, 0x00, 0x00, // R44
0x2B, 0x00, 0x00, // R43
0x2A, 0x00, 0x00, // R42
0x29, 0x00, 0x00, // R41
0x28, 0x00, 0x00, // R40
0x27, 0x00, 0x01, // R39
0x26, 0x00, 0x00, // R38
0x25, 0x05, 0x00, // R37
0x24, 0x00, 0x40, // R36
0x23, 0x31, 0x00, // R35
0x22, 0x00, 0x10, // R34
0x21, 0x00, 0x00, // R33
0x20, 0x10, 0x81, // R32
0x1F, 0x04, 0x01, // R31
0x1E, 0xB1, 0x8C, // R30
0x1D, 0x31, 0x8C, // R29
0x1C, 0x06, 0x39, // R28
0x1B, 0x80, 0x01, // R27
0x1A, 0x0D, 0xB0, // R26
0x19, 0x06, 0x24, // R25
0x18, 0x0E, 0x34, // R24
0x17, 0x11, 0x02, // R23
0x16, 0xE2, 0xBF, // R22
0x15, 0x1C, 0x64, // R21
0x14, 0x27, 0x2C, // R20
0x13, 0x21, 0x20, // R19
0x12, 0x00, 0x00, // R18
0x11, 0x15, 0xC0, // R17
0x10, 0x17, 0x1C, // R16
0x0F, 0x20, 0x01, // R15
0x0E, 0x30, 0x01, // R14
0x0D, 0x00, 0x38, // R13
0x0C, 0x04, 0x08, // R12
0x0B, 0x06, 0x02, // R11
0x0A, 0x00, 0x00, // R10
0x09, 0x00, 0x05, // R9
0x08, 0xC8, 0x02, // R8
0x07, 0x00, 0x00, // R7
0x06, 0x0A, 0x43, // R6
0x05, 0x00, 0x32, // R5
0x04, 0x42, 0x04, // R4
0x03, 0x00, 0x41, // R3
0x02, 0x81, 0xF4, // R2
0x01, 0x57, 0xA0, // R1
0x00, 0x64, 0x70 // R0
};
