HEF4750V datasheet(6/17 Pages) PHILIPS

6 / 17 page

January 1995

Philips Semiconductors

Product speciﬁcation

Frequency synthesizer

HEF4750V

LSI

Fig.4 Phase characteristic of PC1.

PC1 is designed to have a high gain, typically 3200 V/cycle

(at 12,5 kHz). This enables a low noise performance.

Phase comparator 2

Phase comparator 2 (PC2) has a wide range, which

enables faster lock times to be achieved than otherwise

would be possible. It has a linear

± 360° phase range,

which corresponds to a gain of typically 5 V/cycle.

This digital phase comparator has three stable states:

• reset state,

• V’ leads R state,

• R leads V’ state.

Conversion from one state to another takes place

according to the state diagram of Fig.5.

Fig.5 State diagram of PC2.

Output PC2 produces positive or negative-going pulses

with variable width; they depend on the phase relationship

of R and V’. The average output voltage is a linear function

of the phase difference. Output PC2 remains in the high

impedance OFF-state in the region in which PC1 operates.

The resultant phase characteristic is shown in Fig.6.

HEF4750V Datasheet(PDF) 6 Page - NXP Semiconductors