LMK5B12204: How to remove jitter?

Hi Charlie,

Can you please specify what you mean by "debounce"? Are you referring to debouncing from a switch/button input?

Regards,

Jennifer

Hi Jennifer,

"debounce" means  jitter cleaners. Thanks.

Regards,

Charlie

Hi Charlie, 

Do you mean that all the output frequencies will be a mixture of the list you provided (e.g. Config 1) or the same (e.g. Config 2)?

Config 1

• OUT0: 80.566MHz
• OUT1: 201.416MHz
• OUT2: 207.5195MHz
• OUT3: 161.1328MHz

Config 2:

• OUT0: 80.566MHz 
• OUT1: 80.566MHz
• OUT2: 80.566MHz
• OUT3: 80.566MHz

Hi Jennifer,

There is only one clock signal with variable frequency. Sometimes the frequency of this clock is 80.566MHz. Sometimes the frequency of this clock is 201.416MHz. Sometimes the frequency of this clock is 207.5195MHz. Sometimes the frequency of this clock is 161.1328MHz. Sometimes the frequency of this clock is 402.832MHz. Sometimes the frequency of this clock is 415.039MHz.

Now customer choose LMK5B12204 to remove jitter. The input and output clock frequencies of the IC are required to be the same. Can LMK5B12204 be used to only remove jitters? If the answer is yes, is it necessary to use DPLL for removing jitters?

Or is there a more suitable device to recommend to remove jitters? Only the removing jitters function is needed. Thanks.

Regards,

Charlie

Hi Charlie,

The LMK5B12204 can function as a jitter cleaner (primarily in the 12 kHz to 20 MHz integration range). The DPLL can be used to attenuate the close-in phase noise, which is around less than 1 kHz. Otherwise, the device can be used in free-run or clock generator mode where the DPLL is disabled and only APLL1 and APLL2 are used. The better jitter performance in the 12 kHz to 20 MHz range comes from the BAW VCO which is 2.5 GHz. To get your list of frequencies, APLL2 is required which has a range of 5500 - 6250 MHz. I recommend cascading APLL1 output to APLL2 input for improved jitter performance. 

Please provide your phase noise and jitter requirements and I can check if this device will met your specification.

Regards,

Jennifer

Hi Jennifer,

Thank you for your detailed answer.

LMK5B12204 can function as a jitter cleaner (primarily in the 12 kHz to 20 MHz integration range. Does that mean, the frequency of the customer's clock signal is out of range?

Correct the clock accuracy mentioned earlier. The input clocks are 80.56640625MHz, 201.416015625MHz, 207.51953125MHz, 161.1328125MHz, 402.83203125MHz, and 415.0390625MHz.

The jitter and phase noise in LMK5B12204's datasheet meet customer requirements：jitter（rms）＜200fs，phase noise＜130dbc/hz

Please help to confirm whether the accuracy of LMK5B12204 is satisfactory for the above frequency range? Is LMK5B12204 the best fit? Is there a more suitable device for removing jitters? Only the removing jitters function is required. Thanks.

Regards,

Charlie

Hi Charlie,

1. No, jitter integration range is different from frequency output or VCO frequency range. I've attached a sample phase noise plot which showcases the area in which the jitter is calculated. For an output of 212.50 MHz, the jitter of 120 fs was attained by integrating the noise from 12 kHz to 20 MHz offsets.
   1. Please provide the desired jitter integration range for me to confirm the LMK5B12204 meets your spec. 12 kHz to 20 MHz is a common range.
   2. 
2. Yes, it is possible to generate those outputs clocks with such accuracy.

Regards,

Jennifer