CA3130 Operational Amplifier

Overview

The CA3130A and CA3130 are high-performance operational amplifiers that integrate MOSFET input stages with bipolar and CMOS technologies. These op-amps are specifically designed for applications requiring ultra-high input impedance, low input current, and single-supply operation. The combination of MOSFET inputs and CMOS output stages makes them ideal for interfacing with digital circuits and precision analog applications where rail-to-rail performance is required.

These devices are particularly well-suited for battery-powered systems, sensor interfaces, and signal conditioning circuits due to their low power consumption and wide operating voltage range. The CA3130 series offers superior performance compared to conventional bipolar op-amps in applications requiring high input impedance and low bias currents.

Features

• MOSFET Input Stage Provides:
  • Very high input impedance: Z_I = 1.5 TΩ (1.5 × 10¹²Ω) typical
  • Very low input current: I_I = 5pA typical at 15V operation
  • Ultra-low input current: I_I = 2pA typical at 5V operation
• Ideal for single-supply applications
• Common-mode input voltage range includes negative supply rail
• Input terminals can swing 0.5V below negative supply rail
• CMOS output stage permits signal swing to either (or both) supply rails
• Wide supply voltage range: 5V to 16V
• Low power consumption
• High slew rate: 10V/µs typical
• Wide bandwidth: 15MHz typical

Applications

The CA3130 series operational amplifiers find use in a wide variety of analog and mixed-signal applications, including:

• Ground-referenced single supply amplifiers
• Fast sample-hold amplifiers
• Long-duration timers/monostables
• High-input-impedance comparators (ideal interface with digital CMOS)
• High-input-impedance wideband amplifiers
• Voltage followers (e.g., follower for single-supply D/A converter)
• Voltage regulators (permits control of output voltage down to 0V)
• Peak detectors
• Single-supply full-wave precision rectifiers
• Photo-diode sensor amplifiers
• Medical instrumentation
• Portable test equipment
• Data acquisition systems

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V₊ to V_-): 16V
• Differential Input Voltage: ±8V
• Input Voltage Range: (V_--0.5V) to (V₊+0.5V)
• Output Short-Circuit Duration: Continuous
• Operating Temperature Range: -55°C to +125°C
• Storage Temperature Range: -65°C to +150°C

Typical Electrical Characteristics (T_A = 25°C, V_S = ±7.5V)

• Input Offset Voltage: 2mV
• Input Bias Current: 5pA
• Input Offset Current: 0.5pA
• Input Resistance: 1.5TΩ
• Large Signal Voltage Gain: 100V/mV
• Supply Current: 4mA
• Slew Rate: 10V/µs
• Gain Bandwidth Product: 15MHz
• Common Mode Rejection Ratio: 90dB
• Power Supply Rejection Ratio: 90dB
• Output Voltage Swing: Rail-to-rail

Package Information

The CA3130 is available in several industry-standard packages:

8-Pin DIP (Dual Inline Package)

• Package Code: P
• Dimensions: 9.81mm × 6.35mm × 3.3mm
• Pin Pitch: 2.54mm
• Operating Temperature: -55°C to +125°C

8-Pin SOIC (Small Outline Integrated Circuit)

• Package Code: M
• Dimensions: 4.9mm × 3.9mm × 1.25mm
• Pin Pitch: 1.27mm
• Operating Temperature: -55°C to +125°C

8-Pin TSSOP (Thin Shrink Small Outline Package)

• Package Code: MT
• Dimensions: 3.0mm × 4.4mm × 1.0mm
• Pin Pitch: 0.65mm
• Operating Temperature: -55°C to +125°C

Design Considerations

When designing with the CA3130 operational amplifier, several important factors should be considered:

Power Supply Decoupling

Proper power supply decoupling is essential for stable operation. A 0.1µF ceramic capacitor should be placed as close as possible to the power supply pins, with a larger electrolytic capacitor (10µF or greater) for bulk decoupling.

Input Protection

While the MOSFET input stage provides extremely high input impedance, it can be susceptible to electrostatic discharge (ESD) damage. Input protection diodes should be considered in applications where the input might exceed the supply rails or be subject to ESD events.

Output Loading

The CMOS output stage can drive substantial capacitive loads, but excessive capacitive loading (greater than 100pF) may require a small series resistor (50-100Ω) at the output to maintain stability.

Thermal Considerations

While the CA3130 has relatively low power consumption, in high-temperature environments or when driving heavy loads, thermal management should be considered, especially in surface-mount packages.

Conclusion

The CA3130 operational amplifier represents a unique combination of MOSFET input technology with CMOS output capability, making it exceptionally versatile for a wide range of applications. Its ultra-high input impedance, low power consumption, and rail-to-rail output capability make it particularly valuable in single-supply systems, sensor interfaces, and precision analog circuits. The device's robust electrical characteristics and flexible packaging options ensure it remains a popular choice for designers working on both new designs and legacy systems.