8-40

curve of the typical static phase error as a function of the free-

running oscillator frequency is shown in Figure 2. It should be

noted that the slope of the curve determines the DC gain of the

phase-locked loop, i.e., 40Hz per degree.

Thermal Considerations

The circuit of the CA3126 is thermally compensated to achieve

the optimal operating characteristics over the normal operating

temperature range of TV receivers. Figures 3 and 4 show the

oscillator and chroma-output amplitudes and phases as a func-

tion of temperature (Terminals 8 and 15), respectively.

Both the oscillator and chroma-output amplitudes and

phases are measured relative to the chroma-input phase.

The performance of the oscillator free-running frequency as

a function of temperature is shown in Figure 5. All the tem-

perature plots are characteristic of the test circuit with the

indicated component types and values given.

OSCILLATOR FREE-RUNNING FREQUENCY

300

-300

-200

-100

0

100

200

6

400

(DEVIATION IN Hz FROM 3.579545MHz)

4

2

0

-2

-4

FIGURE 2. STATIC PHASE ERROR

PHASE

AMPLITUDE

100

-50

-25

0

25

50

75

60

70

80

90

100

110

-10

-5

0

FIGURE 3. AMPLITUDE AND PHASE VARIATIONS OF

OSCILLATOR OUTPUT vs TEMPERATURE

PHASE

AMPLITUDE

100

-50

-25

0

25

50

75

80

90

100

110

120

130

-10

5

10

15

0

-5

-15

140

3.58MHz CW SIGNAL

FIGURE 4. AMPLITUDE AND PHASE VARIATIONS OF

CHROMA OUTPUT vs TEMPERATURE

125

-50

-25

0

25

50

75

-150

-100

-50

0

50

100

100

FIGURE 5. VARIATION OF OSCILLATOR FREE RUNNING

FREQUENCY vs TEMPERATURE

CA3126