LMX2820EVM: 即时校准时间问题

即时校准的锁定时间问题

我使用TICS Pro模拟即时校准，并用示波器抓取TP_LD的低电平脉冲宽度

TICS Pro采用以下推荐的配置流程，流程来自于链接回复：LMX2820: LMX2820 not locking with instant calibration - Clock & timing forum - Clock & timing - TI E2E support forums

After a Vcc power up, we need to program the device to lock to a certain frequency without InstCal (INSTCAL_EN=0). After the device is locked, then we can initiate the InstCal.

Recommended programming sequence below:

1. Open TICS Pro and select EVM default mode configuration
2. In User Controls page, check all Double Buffer bits
3. In PLL page, uncheck DBLR_CAL_EN in Instant calibration box (if VCO doubler is not needed)
4. Vcc power up the EVM
5. Press Ctrl+L to program the EVM to lock to 6GHz
6. Set INSTCAL_EN = 1 in Instant calibration box
7. Type 5650 and then Enter in the VCO box (PLL_NUM, PLL_N and INSTCAL_PLL_NUM will be programmed automatically)
8. Uncheck FCAL_EN in the VCO calibration box
9. Check FCAL_EN
10. Uncheck FCAL_EN and wait for a while (VCO will lock to 5650 MHz), InstCal is complete.
11. Change VCO frequency, for example, type 5800 and then Enter in the VCO box (PLL_NUM, PLL_N and INSTCAL_PLL_NUM will be programmed automatically)
12. Click Calibrate VCO button (this will write R0 once, VCO will lock to 5800 MHz)
13. Change VCO frequency to 6200 MHz
14. Click Calibrate VCO button (this will write R0 once, VCO will lock to 6200 MHz)

在VCO与VCO Divider模式下，即时校准的跳频锁定时间在6-7us之间，但手册给出的即时校准时间为2.5us，在VCO Doubler 模式下，跳频锁定时间在60-70us之间

• 为什么即时校准的锁定时间会超过5us，中间是包含了稳定时间吗？
• 为什么使用输出倍频器后，锁定时间明显的变长了？是需要进行其他操作吗？