Description
The Basic Comparator
Figure 4 shows the basic circuit diagram for one of the two comparators in the CA3290. It is generically similar to the industry type “139” comparators, with PMOS transistors replacing PNP transistors as input stage elements.Transistors Q1 through Q4 comprise the differential input stage, with Q5 and Q6 serving as a mirror connected active load and differential-to-single-ended converter.The differential input at Q1 and Q4 is amplified so as to toggle Q6 in accordance with
Features
- MOSFET Input Stage - Very High Input Impedance (ZIN).
- . . . 1.7TΩ (Typ) - Very Low Input Current at V+ = 5V.
- . . 3.5pA (Typ) - Wide Common Mode Input Voltage Range (VICR) Can Be Swung 1.5V (Typ) Below Negative Supply Voltage Rail - Virtually Eliminates Errors Due to Flow of Input Currents.
- Output Voltage Compatible with TTL, DTL, ECL, MOS, and CMOS Logic Systems in Most.