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ADF4158+BGT24MTR11 Frequency lock

I am developing a CW radar using the ADF4158+BGT24MTR11, the BGT24MTR11 is currently working and I am ready to set the lock frequency to 23.5GHZ(This frequency is divided by 16 and then input to the ADF4158),However, when I wrote the configuration information of the ADF4158, the modulation voltage output reached 3.2V, which was far beyond the VCO range of the BGT24MTR11。

Configuration information:
unsigned char R0[] = { 0x00, 0x24, 0xB8, 0x00}; // 23.50001 GHz
unsigned char R1[] = {0x02, 0x26, 0x00, 0x01}; // 23.50001 GHz
unsigned char R2[] = { 0x02, 0x00, 0xFD, 0x02};
unsigned char R3[] = { 0x00, 0x00, 0x00, 0x43};
unsigned char R4[] = { 0x00, 0x18, 0xF4, 0x04};
unsigned char R5_load1[] = { 0x00, 0x49, 0x40, 0x05};
unsigned char R5_load2[] = { 0x00, 0x80, 0x00, 0x7D};
unsigned char R6_load1[] = { 0x00, 0x00, 0x00, 0x56};
unsigned char R6_load2[] = { 0x00, 0x80, 0x00, 0x06};
unsigned char R7[] = { 0x00, 0x02, 0xFD, 0x07};
void ADF4158_config(void)

WriteToADF4158(R0); //last one to be loaded (double-buffered).

23.5GHZ corresponding voltage range:

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  • Hi ,

    I investigated BGT24MTR11 and found that this chip has two different Vtune structures. Did you set the COARSE Vtune value to achieve 23.5 GHz? Can you debug the system by using the following method?

    - First set Coarse Vtune value to achieve 23.5GHz

    -Set ADF4158  Charge pump Tri-state mode to enabled.

    - Apply 2V to Fine Vtune of BGT24MTR11

    - Observe the frequency. If the frequency is close the 23.5GHz then we will further investigate the PLL. 

    By the way, according to the BGT24MTR11 datasheet, 23.5GHz is not supported.