ML7404 Family LSIs
Hardware Design Manual
FEXL7404DG-03
8
4. VCO
Figure 4.1 shows a configuration example of the VCO tank circuit. VCO oscillator frequency calculated as
follows:
LC
F
π
2
1
=
The L in the above equation will be the sum of the inductor L1, the line inductance of the PCB and the internal
inductance of the ML7404. And the C will be the sum of the capacitor C1, the line capacitor of the PCB and the
internal capacitor (including calibration capacitor) of the ML7404. Table 4.1 shows the typical value of internal
capacitor.
Figure 4.1 VCO tank circuit configurations
Table 4.1: Internal capacitor value
VCO_CAL[6:0](B0, 0x6E)
Internal capacitor value[pF]
0x00
2.94pF
0x40
2.46pF
0x7F
1.97pF
conditions
：
LP(#26) pin voltage
（
VCO tuning voltage
）
=0.75V
IND1(#28)
Variable capacitor
Amplifier
C1
L1
IND2(#30)
Variable capacitor
for calibration
