FDC2214: the value of L and C

Takao Yamamoto

Genius 4135 points

Dear all,

I would like to know how to set the value of L and C.

You mentioned that 'f sensor' is 0.01~10 MHz.

In other words, we must set L and C to be within above value.

Question...

Is there no limit about the value of L and C if 'f sensor' is 0.01~10 MHz?

Best regards,

over 9 years ago

0 Takao Yamamoto over 9 years ago

Genius 4135 points

In addition,

Is it OK to use following formula?
'f sensor' = 1/2π√(LC)

Regards,

0 Yibo Yu over 9 years ago in reply to Takao Yamamoto

TI__Expert 8050 points

Hi Yamamoto-san,

In general, you should keep the fixed C small because a large C in the LC tank could overwhelm the change in capacitance that needs to be detected.

The equation is correct. Please note that C is the total capacitance, which includes the surface mount capacitor, parasitic capacitance, and sensor capacitance.

Regards,
Yibo

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FDC2214: the value of L and C