Common-Mode Rejection Ratio of MOS Controlled Source Transistor Calculator

Common-Mode Rejection Ratio Formula:

\[ CMRR_{db} = \frac{|\text{Differential Gain}_{db}|}{|\text{Common Mode Gain}_{db}|} \]

Common-Mode Rejection Ratio (dB):

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1. What is Common-Mode Rejection Ratio?

The Common-Mode Rejection Ratio (CMRR) is a measure of the ability of an electronic circuit to reject common-mode signals, which are signals that appear on both input terminals of the circuit. It's particularly important in differential amplifiers and operational amplifiers.

2. How Does the Calculator Work?

The calculator uses the CMRR formula:

\[ CMRR_{db} = \frac{|\text{Differential Gain}_{db}|}{|\text{Common Mode Gain}_{db}|} \]

Where:

\( \text{Differential Gain}_{db} \) — The amplification of differential signals in decibels
\( \text{Common Mode Gain}_{db} \) — The amplification of common-mode signals in decibels

Explanation: The CMRR quantifies how effectively a circuit rejects signals that are common to both inputs while amplifying the difference between them.

3. Importance of CMRR Calculation

Details: High CMRR is crucial for accurate signal processing in noisy environments, medical instrumentation, audio equipment, and communication systems where common-mode noise needs to be suppressed.

4. Using the Calculator

Tips: Enter both differential gain and common mode gain values in decibels. Ensure values are non-zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: Why is CMRR important in MOS controlled source transistors?
A: High CMRR ensures that the transistor effectively rejects common-mode noise while amplifying differential signals, which is critical for precision analog circuits.

Q2: What are typical CMRR values for good amplifiers?
A: Good amplifiers typically have CMRR values of 80-120 dB or higher, indicating excellent common-mode rejection capability.

Q3: How does temperature affect CMRR?
A: Temperature variations can affect component matching and thus impact CMRR. Higher quality components maintain better CMRR over temperature ranges.

Q4: Can CMRR be improved in circuit design?
A: Yes, through careful component matching, using higher quality components, and employing techniques like current mirroring and cascode configurations.

Q5: What's the difference between CMRR and PSRR?
A: CMRR measures rejection of common-mode input signals, while PSRR (Power Supply Rejection Ratio) measures rejection of power supply variations.