Operational amplifiers allow circuits to amplify, process, and control electrical signals with high precision. Among the many op-amps available, the CA3130 MOSFET operational amplifier stands out for its unique BiMOS architecture, which combines MOSFET inputs with CMOS output technology. This article will discuss the CA3130 MOSFET op-amp, including its circuit operation, technical specifications, etc.

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CA3130 MOSFET Op-Amp Basic

The CA3130 is a high-speed BiMOS operational amplifier that combines the advantages of MOSFET and CMOS technologies in a single device. It features a MOSFET input stage and a CMOS output stage, which together provide very high input impedance, extremely low input current, and fast signal response. Because of these characteristics, the CA3130 is designed to handle sensitive analog signals while maintaining stable and accurate amplification.

The input stage of the CA3130 uses gate-protected P-channel MOSFET transistors that allow the amplifier to achieve excellent input characteristics. This design enables the device to work with a common-mode input voltage that can extend slightly below the negative supply terminal, which is particularly useful in single-supply systems.

In the output stage, a CMOS transistor pair allows the output voltage to swing very close to the supply rails when the load impedance is high. The CA3130 series typically operates with supply voltages from 5V to 16V and supports offset voltage adjustment through dedicated terminals.

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CA3130 MOSFET Op-Amp CAD Models

CA3130 MOSFET Op-Amp Pinout Details

Alternatives & Equivalent Model

• CA3130A

• CA3140

• CA3240

• LF351

• TL071

CA3130 Ordering IC Variant

CA3130 MOSFET Op-Amp Circuit Diagram

The CA3130 internal circuit diagram shows how different transistor stages work together to amplify signals. The circuit begins with a bias network, which includes zener diode Z1 and several diodes and resistors. This section generates stable reference voltages and bias currents that allow the internal transistors to operate correctly and maintain stable performance.

The input stage uses MOSFET transistors that form a differential amplifier. The non-inverting and inverting input signals are applied here, and the circuit compares the difference between these two signals. Because MOSFET devices are used, the input stage provides extremely high input impedance and very low input current.

After the input stage, the signal moves to the second amplification stage, where additional gain is provided. Transistors in this section increase the voltage level of the differential signal so that it can effectively drive the output stage. Current source circuits help control the operating current and improve amplifier stability.

The output stage consists of CMOS transistors that deliver the amplified signal to the output pin. This design allows the output voltage to swing very close to the supply rails when the load impedance is high, enabling efficient signal amplification. Additional terminals are provided for offset adjustment, frequency compensation, and strobing control.

Technical Specifications

Specifications of CA3130EZ part model:

CA3130 MOSFET Op-Amp Features

MOSFET Input Stage with Very High Input Impedance

The CA3130 uses a MOSFET input stage that provides extremely high input impedance of about 1.5 TΩ (typical). This allows the amplifier to work with very sensitive signals while drawing almost no current from the input source.

Very Low Input Current

The device has an exceptionally low input current of around 5 pA typical at 15V operation and 2 pA typical at 5V operation. This helps improve measurement accuracy and minimizes signal loss in high-impedance circuits.

Ideal for Single-Supply Operation

The CA3130 is designed to operate efficiently with a single power supply, making it suitable for systems where dual power rails are not available.

Wide Common-Mode Input Voltage Range

The amplifier supports a common-mode input voltage range that includes the negative supply rail, allowing input signals to go slightly below the negative supply voltage.

Input Terminals Can Swing Below the Negative Supply

The input terminals can swing about 0.5 V below the negative supply rail, improving flexibility when working with low-level signals in single-supply circuits.

CMOS Output Stage

The CMOS output stage allows the output voltage to swing close to either or both supply rails, enabling better signal range and efficient output performance.

Rail-to-Rail Output Capability (High Load Impedance)

With high load impedance, the CA3130 output can swing within a few millivolts of the supply rails, improving the usable output voltage range.

Pb-Free and RoHS Compliant

The device is available in Pb-free packages with annealed leads, meeting modern RoHS environmental compliance standards.

How to Use the CA3130 MOSFET Op-Amp

The CA3130 is a BiMOS operational amplifier that amplifies the voltage difference between two input terminals. It includes a non-inverting input (pin 3) and an inverting input (pin 2). The output voltage depends on the comparison between these two inputs. When the voltage at the non-inverting input is higher than the inverting input, the output moves toward the positive supply. When the inverting input becomes higher, the output shifts toward the negative side. This differential operation allows the CA3130 MOSFET op-amp to amplify small signal changes with high accuracy.

Circuit 1: Single-Supply Operation

In Circuit 1, the CA3130 works with a single power supply. The V+ pin (pin 7) connects to a +5V source, while the V− pin (pin 4) connects to ground. Input signals enter through pins 2 and 3. The amplified output appears at pin 6 and drives the load resistor R_L. This configuration provides a simple way to amplify or compare signals in low-voltage analog circuits.

Circuit 2: Dual-Supply Configuration

Circuit 2 shows the CA3130 using a dual power supply of +7.5V and −7.5V. This arrangement allows the amplifier to process signals that move above and below ground. Capacitors connected near the supply pins help reduce noise and improve stability.

Resistors and a small compensation capacitor help control the frequency response and maintain stable operation. This design shows how the CA3130 MOSFET op-amp can handle precision signal processing while maintaining reliable performance.