对于窄带系统，可能需要通过调整环路带宽来修改相位噪声整形。较高的环路带宽可提供更佳的近端相位噪声。对于某些系统，RX 和 TX 可能需要不同的环路带宽，因为要使 TX 参数（ACP、近端杂散）产生良好结果，可能需要与在 RX 中获得良好近端选择性不同的环路 BW。

下面的覆盖项对 CC13x2 有效。如果需要下面未列出的环路带宽，请提出要求。

环路带宽：20kHz

//Synth: Set loop bandwidth after lock to 20 kHz (K2)
(uint32_t)0x0A480583,
//Synth: Set loop bandwidth after lock to 20 kHz (K2)
(uint32_t)0x000005A3,
//Synth: Set loop bandwidth after lock to 20 kHz (K3, LSB)
(uint32_t)0x7AB80603,
//Synth: Set loop bandwidth after lock to 20 kHz (K3, MSB)
(uint32_t)0x00000623,
//Synth: Set FREF = 8 MHz
(uint32_t)0x000684A3,

环路带宽：40kHz

//Synth: Set loop bandwidth after lock to 40 kHz (K2)
(uint32_t)0x29200583,
//Synth: Set loop bandwidth after lock to 40 kHz (K2)
(uint32_t)0x000005A3,
//Synth: Set loop bandwidth after lock to 40 kHz (K3, LSB)
(uint32_t)0xF5700603,
//Synth: Set loop bandwidth after lock to 40 kHz (K3, MSB)
(uint32_t)0x00000623,
//Synth: Set FREF = 4 MHz
(uint32_t)0x000C84A3,

环路带宽：60kHz

//Synth: Set loop bandwidth after lock to 60 kHz (K2)
(uint32_t)0x5C870583,
//Synth: Set loop bandwidth after lock to 60 kHz (K2)
(uint32_t)0x000005A3,
//Synth: Set loop bandwidth after lock to 40 kHz (K3, LSB)
(uint32_t)0x70280603,
//Synth: Set loop bandwidth after lock to 40 kHz (K3, MSB)
(uint32_t)0x00010623,
//Synth: Set FREF = 4 MHz
(uint32_t)0x000C84A3,

环路带宽：80kHz

//Synth: Set loop bandwidth after lock to 80 kHz (K2)
(uint32_t)0xA47E0583,
//Synth: Set loop bandwidth after lock to 80 kHz (K2)
(uint32_t)0x000005A3,
// Synth: Set loop bandwidth after lock to 80 kHz (K3, LSB)
(uint32_t)0xEAE00603,
//Synth: Set loop bandwidth after lock to 80 kHz (K3, MSB)
(uint32_t)0x00010623,
//Synth: Set FREF = 8 MHz
(uint32_t)0x000684A3,

环路带宽： 150kHz

//Synth: Set loop bandwidth after lock to 150 kHz (K2)
(uint32_t)0x424C0583,
//Synth: Set loop bandwidth after lock to 150 kHz (K2)
(uint32_t)0x000205A3,
//Synth: Set loop bandwidth after lock to 150 kHz (K3, LSB)
(uint32_t)0x98630603,
//Synth: Set loop bandwidth after lock to 150 kHz (K3, MSB)
(uint32_t)0x00030623,
//Synth: Set FREF = 8 MHz
(uint32_t)0x000684A3,

环路带宽：200 kHz

//Synth: Set loop bandwidth after lock to 200 kHz (K2)
(uint32_t)0x04150583,
//Synth: Set loop bandwidth after lock to 200 kHz (K2)
(uint32_t)0x000405A3,
//Synth: Set loop bandwidth after lock to 200 kHz (K3, LSB)
(uint32_t)0xCB2F0603,
//Synth: Set loop bandwidth after lock to 200 kHz (K3, MSB)
(uint32_t)0x00040623,
// Synth: Set FREF = 8 MHz
(uint32_t)0x000684A3,

其他覆盖项：

在某些情况下，使用 FREF 抖动可以获得更好的结果：

//Synth: Set FREF dither = 9.6 MHz
(uint32_t)0x000584B3,

使用 IIR 滤波器有助于降低环路滤波器 BW 之外的相位噪声，但会增加一些功耗。如果在上面给出的设置下，远端相位噪声过高，则可以测试下面的覆盖项。

//Two word override starting from LoopCoeff
HW32_ARRAY_OVERRIDE(0x4028,2),
// IIR EN, 2nd order, IIR_FILT_BW=1
(uint32_t)0x38000000,
//Set RFC_FSCA:PLLCTL0.IIR_CLK_DIV to 1
(uint32_t)0x01608402,