开发板CMOS接口用的是BPWM作为CMOS的输入时钟信号，BPWM输出100KHz时是方波，但是输出10MHz时波形有点像三角波，波形如图片所示。请问这是什么原因造成的？谢谢
用的是BSPSampleCodeStdDriverBPWM_SwitchDuty的代码
    /* Enable BPWM0 clock source */
    CLK_EnableModuleClock(BPWM0_MODULE);

    /* Select BPWM module clock source */
    CLK_SetModuleClock(BPWM0_MODULE, CLK_CLKSEL2_BPWM0SEL_PLL, 0);

    SYS_ResetModule(BPWM0_MODULE);


    /* Set PG.10 multi-function pin for BPWM0 channel 4 */
    SYS->GPG_MFPH  = ~SYS_GPG_MFPH_PG10MFP_Msk;
    SYS->GPG_MFPH |= SYS_GPG_MFPH_PG10MFP_BPWM0_CH4;


    /* BPWM0 channel 4 frequency is 10000000Hz, duty 50%, */
    BPWM_ConfigOutputChannel(BPWM0, 4, 10000000, 50);

    /* Enable output of BPWM0 channel 4 */
    BPWM_EnableOutput(BPWM0, BPWM_CH_4_MASK);

    /* Start BPWM counter */
    BPWM_Start(BPWM0, BPWM_CH_4_MASK);