LMX1501 datasheet(17/22 Pages) NSC

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Application Information (Continued)

Example

KVCO e 193 MHzV

Kw e 5 mA (Note 1)

RFopt e 886 MHz

Fref e 25 kHz

N e RFopt fref e 35440

0p e 2q 5 kHz e 31415e4

wp e 43

ATTEN e 10 dB

T1 e

secwp b tanwp

138eb5

T3 e

010(1020)b1

(2q

25e3)2

9361eb6

0c e

(tan 43 )

(138eb5 a 9361eb6)

(138eb5 a 9361eb6)2 a 138eb5

9361eb6

01a(138eb5a9361eb6)

2 a 138eb5 9361eb6

(tan 43 )

(138eb5 a 9361eb6) 2

(

18101e4

T2 e

(18101e4)2

(138eb5 a 9361eb6)

1318eb4

C1 e

138eb5

1318eb4

(5eb3)

193e6

(18101e4)2

(35440)

1 a (18101e4)2

(1318eb4)2

1 a (18101e4)2

(138eb5)2 1 a (18101e4)2 (9361eb6)2

(

2153 nF

C2 e 2153 nF

1318eb4

1384eb5

J e1835nF

R2 e

1318eb4

1835eb9

718 kX

if we choose R3 e 120k then C3 e

9361eb6

120e3

78 pF

Converting to standard component values gives the follow-

ing filter values which are shown in

Figure 4

C1 e 2200 pF

R2 e 82 kX

C2 e 0018 mF

R3 e 120 kX

C3 e 78 pF

Note 1

See related equation for Kw in Charge Pump Current Specification

Definitions For this example VP e 50V The value for Kw can then

be approximated using the curves in the Typical Performance Char-

acteristics for Charge Pump Current vs Do Voltage The units for Kw

are in mA You may also use Kw e (5 mA2q rad) but in this case

you must convert KVCO to (radV) multiplying by 2q

TLW12340 – 41

FIGURE 4 E5 kHz Loop Filter

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