Frequency accuracy (synchranization)

[karote]

How do I interpret this:

The allowed system clock and RF center frequency error in normal synchronized mode is +/- 2ppm. If system clock is 100 MHz anf RF carrier is 3 GHz, does this mean that RF carrier can deviate +/-2 *10^6 *3 GHz = >+/- 6kHz

Or how should I understand this requirement?

Thanks

 

[RFDave]

It look's like you have that correct. If the +/- 2 PPM spec applies to the system clock as well, then that can move by (+/- 2e-6)*100 MHz = +/- 200 Hz.

Dave

 

[ilovebow]

yeah, I have check the model files.

But there are two equations about L value.

One is only depended on "rad" and other one is depended on "nr ".

3x

; .subckt spiral_rad : Typical model for Inductance varies with radius
; .subckt spiral_turn : Typical model for Inductance varies with turns
;
; Model name turn rad (um)
; low high low high
; ------------------------------------------------------
; spiral_turn 2.5 7.5 60 60
; ------------------------------------------------------
; spiral_rad 4.5 4.5 30 150
; ------------------------------------------------------
;
; **spiral_turn: only discret turn numbers are available,including 2.5, 3.5, 4.5, 5.5, 6.5 and 7.5
; **spiral_rad: scaled by inner edge-to-edge radius, the details see SPICE document
;
;*************************************************************************************************
define TSMC_CM018RF_RF_SUBCKT_inda_rf ( top bottom)
parameters nr=2.5
; L = L(nr)
L:ls top n2 L=(0.40425*nr*nr-0.995*nr+2.3295)*1.0e-9*l_fac
R:rs n2 bottom R=(1.029*nr-0.746)*rm6_fac
C:cs top bottom C=(6.243*nr+5.803)*1.0e-15*cs_fac
C:cox1 top n1 C=(32.526*nr-14.405)*1.0e-15*cm6_fac
C:cox2 bottom n3 C=(32.683*nr-25.194)*1.0e-15*cm6_fac
C:csub1 n1 0 C=(11.561*nr+9.1643)*1.0e-15*csub_fac
C:csub2 n3 0 C=(11.561*nr+9.1643)*1.0e-15*csub_fac
R:rsub1 n1 0 R=(-18.489*nr+487.7)*rsub_fac
R:rsub2 n3 0 R=(-18.489*nr+487.7)*rsub_fac
end TSMC_CM018RF_RF_SUBCKT_spiral_turn

define TSMC_CM018RF_RF_SUBCKT_indb_rf ( top bottom)
parameters rad=3e-05
; L = L(rad)
L:ls top n2 L=(0.0916*rad*1.0e6+0.7461)*1.0e-9*l_fac
R:rs n2 bottom R=(0.031*rad*1.0e6+1.8553)*rm6_fac
C:cs top bottom C=(0.2289*rad*1.0e6+21.092)*1.0e-15*cs_fac
C:cox1 top n1 C=(0.811*rad*1.0e6+79.292)*1.0e-15*cm6_fac
C:cox2 bottom n3 C=(0.9108*rad*1.0e6+59.886)*1.0e-15*cm6_fac
C:csub1 n1 0 C=(0.1611*rad*1.0e6+50.779)*1.0e-15*csub_fac
C:csub2 n3 0 C=(0.1611*rad*1.0e6+50.779)*1.0e-15*csub_fac
R:rsub1 n1 0 R=(-0.575*rad*1.0e6+433.38)*rsub_fac
R:rsub2 n3 0 R=(-0.575*rad*1.0e6+433.38)*rsub_fac
end TSMC_CM018RF_RF_SUBCKT_indb_rf