- #1
nobrainer612
- 26
- 0
AC coupling using NMOS
Hello. What does AC coupling by using NMOS and PMOS actually means?
Hello. What does AC coupling by using NMOS and PMOS actually means?
Last edited:
Oh! The invisible blue waveform. I had not noticed it!nobrainer612 said:my question is, shouldn't the blue wave from the circuit built by PMOS has the same waveform and value as NMOS?
AC coupling using NMOS and PMOS is a technique used to remove the DC offset from an input signal while preserving the AC component. It involves using a capacitor and two complementary metal-oxide-semiconductor (CMOS) transistors, one NMOS and one PMOS, to block the DC component and pass the AC component of the input signal.
The input signal is first connected to the gate of the NMOS transistor, while the source is connected to ground. The drain of the NMOS is connected to the gate of the PMOS, and the source is connected to the power supply rail. A capacitor is connected between the drain of the PMOS and the output. The DC component of the input signal is blocked by the NMOS, while the AC component passes through to the PMOS. The PMOS then amplifies and inverts the signal, which is then passed through the capacitor to the output. This results in a purely AC output signal.
One advantage is that CMOS technology offers low power consumption and high integration density, making it suitable for use in many applications. Additionally, the use of complementary transistors ensures that the output signal is not distorted and maintains a high signal-to-noise ratio. AC coupling using NMOS and PMOS also allows for the removal of large DC offsets, which may be present in some input signals.
One limitation is that the capacitor used in the circuit must be large enough to pass the desired AC frequency range without significant attenuation. This can result in a larger physical size of the circuit and may also introduce unwanted phase shifts. Additionally, the use of complementary transistors in the circuit requires precise matching, which can be challenging to achieve in practice.
AC coupling using NMOS and PMOS is commonly used in audio amplifiers, where it allows for the removal of DC offsets and improves the overall sound quality. It is also used in data transmission systems, such as in high-speed serial communication, to remove DC offsets and restore the original signal. This technique can also be found in medical devices, instrumentation, and other electronic systems where a clean AC signal is required.