TLC2932

HIGH-PERFORMANCE PHASE-LOCKED LOOP

SLAS097E – SEPTEMBER 1994 – REVISED MAY 1997

17

POST OFFICE BOX 655303

APPLICATION INFORMATION

basic design example (continued)

Assume the loop has to have a 100

response curves of Figure 26, a value of 4.5 radians is selected for

selection gives a good combination for settling time, accuracy, and loop gain margin. The initial parameters are

Table 6 shows these values.

The natural loop frequency is calculated as follows:

wnts + 4.5

Then

wn +

4.5

100

ms +

45 k-radians sec

Since

Table 5. Design Parameters

PARAMETER

SYMBOL

VALUE

UNITS

Division factor

N

8

Lockup time

t

100

µs

Radian value to selected lockup time

ωnt

4.5

rad

Damping factor

ζ

0.7

Table 6. Device Specifications

PARAMETER

SYMBOL

VALUE

UNITS

VCO gain

76.6

Mrad/V/s

fMAX

70

MHz

fMIN

KV

20

MHz

VIN MAX

5

V

VIN MIN

0.9

V

PFD gain

Kp

0.342357

V/rad

Table 7. Calculated Values

PARAMETER

SYMBOL

VALUE

UNITS

Natural angular frequency

ωn

45000

rad/sec

3.277

Mrad/sec

Lag-lead filter

Calculated value

Nearest standard value

R1

15870

16000

Ω

Calculated value

Nearest standard value

R2

308

300

Ω

Selected value

C1

0.1

µF