Small Signal Op-Amp Amplifiers
A comprehensive guide to various small signal operational amplifier configurations and their applications.
Transconductance Amplifier (OTA)
Converts an input voltage to an output current. Also known as a Voltage-Controlled Current Source (VCCS).
Key Parameters
- Transconductance (gm): The ratio of output current to input voltage
- Input Impedance: Typically very high (ideally infinite)
- Output Impedance: Typically very high (ideally infinite)
Applications
- Voltage-controlled oscillators (VCOs)
- Active filters
- Analog multipliers
- Voltage-controlled amplifiers
- Analog computation circuits
Design Considerations
The transconductance parameter gm is often controlled by a bias current. In integrated circuits, OTAs are commonly used because they can be implemented with fewer components than traditional op-amps.
The output current of an ideal OTA is: