芯片, 74HCT CMOS逻辑器件
The is a high-speed Si-gate CMOS Device and are pin compatible with the "4046" of the "4000B" series. They are specified in compliance with JEDEC standard no. 7A. The 74HCT4046A is phase-locked-loop circuits that comprise a linear voltage-controlled oscillator VCO and three different phase comparators PC1, PC2 and PC3 with a common signal input amplifier and a common comparator input. The signal input can be directly coupled to large voltage signals or indirectly coupled with a series capacitor to small voltage signals. A self-bias input circuit keeps small voltage signals within the linear region of the input amplifiers. With a passive low-pass filter, the "4046A" forms a second-order loop PLL. The excellent VCO linearity is achieved by the use of linear op-amp techniques. The VCO requires one external capacitor C1 between C1A and C1B and one external resistor R1 between R1 and GND or two external resistors R1 and R2 between R1 and GND and R2 and GND.