UNISONIC TECHNOLOGIES CO., LTD

U74HC4046A

CMOS IC

www.unisonic.com.tw

1 of 19

Copyright © 2013 Unisonic Technologies Co., Ltd

QW-R502-461.C

PHASE LOCKED LOOP WITH VCO

DESCRIPTION

The U74HC4046A is a phase-locked-loop circuit including a linear

voltage-controlled oscillator (VCO), three different phase comparators

(PC1, PC2 and PC3), a common signal input amplifier and a common

comparator input.

The signal can be directly coupled to large voltage signals or with a

series capacitor coupled to small voltage signals. Small voltage signals

can be kept within the linear region of the input amplifiers with a self-bias

input circuit. The U74HC4046A and a passive low-pass filter form a

second-order loop PLL. With a linear op-amp, the VCO achieves excellent

linearity.

The VCO requires an external capacitor and resistor. R1 (between R1

and GND) and capacitor C1 (between C1A and C1B) determine the

frequency range of the VCO. R2 (between R2 and GND) enables the

VCO to have a frequency offset if required.

SOP-16

TSSOP-16

For the high input impedance of the VCO, the design of low-pass filters is simplified, and the designer has a wide

the VCO input is held at a constant DC level, the VCO output signal has a duty factor of 50% (maximum expected

deviation 1%). A LOW level at the inhibit input (INH) enables the VCO and demodulator, while a HIGH level turns

both off to minimize standby power consumption.

FEATURES

* Low Power Consumption

* Operating Power Supply Voltage Range: Digital Section 2.0 to 6.0 V

VCO Section 3.0 to 6.0 V

* Excellent VCO Frequency Linearity

* VCO-Inhibit Control For ON/OFF Keying and for Low Standby Power Consumption

* Minimal Frequency Drift

* Three Phase Comparators:

EXCLUSIVE-OR;

Edge-Triggered JK Flip-Flop;

Edge-Triggered RS Flip-Flop

* Zero Voltage Offset due to OP-Amp Buffering

* Standard Output Capability