The development of the times, the demand for materials, digital integrated circuits can be divided into bipolar integrated circuits (mainly TTL) and unipolar integrated circuits (CMOS, NMOS, PMOS, etc.) according to the conductivity type. The single-gate static power consumption of a CMOS circuit is on the order of nanowatts (nw). Today we will focus on learning the contents of CMOS integrated circuits and mastering it.
Introduction to CMOS integrated circuits
CMOS Complementary Metal Oxide Semiconductor, an amplifier component for voltage control. It is the basic unit that makes up a CMOS digital integrated circuit.
A transistor of a metal-oxide-semiconductor structure is referred to as a MOS transistor, and has a P-type MOS transistor and an N-type MOS transistor. An integrated circuit composed of a MOS transistor is referred to as a MOS integrated circuit, and a complementary MOS integrated circuit composed of a PMOS transistor and an NMOS transistor is a CMOS-IC (Complementary MOS Integrated CIRcuit).
CMOS integrated circuit performance characteristics Micro DC Power Consumption—The single-gate static power consumption of CMOS circuits is on the order of nanowatts (nw).
High Noise Tolerance—The noise margin of a CMOS circuit is typically above 40% supply voltage.
Wide operating voltage range—The supply voltage for CMOS circuits is typically 1.5 to 18 volts.
High logic swing—the CMOS circuit outputs high and low amplitudes to full voltage
"1" is VDD and logic "0" is VSS.
High Input Impedance - The input impedance of a CMOS circuit is greater than 108 Ω, typically up to 1010 Ω.
High fan-out capability - CMOS circuits have a fan-out capability greater than 50.
Low Input Capacitance - The input capacitance of a CMOS circuit is typically no greater than 5 PF.
Wide operating temperature range—The CMOS circuit in ceramic package has an operating temperature range of - 55 0C ~ 125 0C; the plastic CMOS circuit is – 40 0C ~ 85 0C.
All inputs have de-protected circuits, good anti-irradiation characteristics, etc.
CMOS vs. TTL CMOS development is later than TTL, but with its higher superiority, it has gradually replaced TTL in many occasions.
The following compares the performance of the two, we all know the reason.
1. CMOS is a FET, TTL is a bipolar transistor
2. CMOS logic level range is relatively large (5 ~ 15V), TTL can only work at 5V
3. The difference between the high and low levels of CMOS is relatively large, the anti-interference is strong, the TTL is small, and the anti-interference ability is poor.
4. CMOS power consumption is small, TTL power consumption is large (1 ~ 5mA / gate)
5. CMOS operating frequency is slightly lower than TTL, but high-speed CMOS speed is almost equal to TTL.
Precautions for the use of CMOS integrated circuits 1) CMOS circuit voltage control device, its input total resistance is very large, the ability to capture interference signals is very strong. Therefore, do not use the unused pins. Connect a pull-up resistor or a pull-down resistor to give it a constant level.
2) When inputting the signal source of the low internal group, connect the current limiting resistor between the input terminal and the signal source to limit the input current to 1mA.
3) When the long signal transmission line is connected, the matching resistor is connected at the CMOS circuit.
4) When the input terminal is connected to a large capacitor, the resistor should be indirectly protected at the input and capacitor. The resistance value is R=V0/1mA. V0 is the voltage on the external capacitor.
5) If the input current of the CMOS exceeds 1 mA, it is possible to burn out the CMOS.
