The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LS/ALSTTL outputs.
The IN74HC4046A phase-locked loop contains three phase comparators, a voltage-controlled oscillator (VCO) and unity gain opamp DEMOUT. The comparators have two common signal inputs, COMPIN, and SIGIN. Input SIGIN and COMPIN can be used directly coupled to large voltage signals, or indirectly coupled (with a series capacitor to small voltage signals). The self-bias circuit adjusts small voltage signals in the linear region of the amplifier.
Applications include FM and FSK modulation and demodulation, frequency synthesis and multiplication, frequency discrimination, tone decoding, data synchronization and conditioning, voltage-to-frequency conversion and motor speed control.

• Low Power Consumption Characteristic of CMOS Device
• Operating Speeds Similary to LS/ALSTTL
• Wide Operating Voltage Range: 3.0 to 6.0 V
• Low Input Current: 1.0 µA Maximum (except SIGIN and COMPIN)
• Low Quiescent Current: 80 µA Maximum (VCO disabled)
• High Noise Immunity Characteristic of CMOS Devices
• Diode Protection on all Inputs