Transconductance in CE amplifier circuit is defined as

Options

A. Ratio of change in collector current to the change in emitter current
B. Ratio of change in input base-emitter voltage to the change in emitter current
C. Ratio of change in collector current to the change in input base-emitter voltage
D. Ratio of change in emitter current to the change in input base-emitter voltage

Answer

To solve the question regarding the definition of transconductance in a common emitter (CE) amplifier circuit, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Transconductance**:
- Transconductance, denoted as \( g_m \), is a key parameter in amplifier circuits, particularly in a common emitter configuration. It indicates how effectively the amplifier converts changes in input voltage to changes in output current.

2. **Defining Transconductance**:
- The transconductance \( g_m \) is defined mathematically as the ratio of the change in collector current (\( \Delta I_C \)) to the change in base-emitter voltage (\( \Delta V_{BE} \)).
- The formula can be expressed as:
\[ g_m = \frac{\Delta I_C}{\Delta V_{BE}} \]

3. **Understanding the Components**:
- \( \Delta I_C \): This represents the change in the collector current when there is a small change in the base-emitter voltage.
- \( \Delta V_{BE} \): This is the small change in the base-emitter voltage that causes the change in collector current.

4. **Conclusion**:
- Therefore, the transconductance in a common emitter amplifier circuit is defined as the ratio of the change in collector current to the change in base-emitter voltage, which can be summarized as:
\[ g_m = \frac{\Delta I_C}{\Delta V_{BE}} \]