CA3193 Precision Operational Amplifier

Overview

The CA3193 and CA3193A are ultra-stable, precision instrumentation operational amplifiers that combine PMOS and bipolar transistors on a single monolithic chip. These amplifiers are internally phase compensated and offer a gain bandwidth product of 1.2MHz. They are designed to be pin-compatible with the industry-standard 741 series operational amplifiers, making them suitable replacements in most applications. The CA3193 series is also functionally compatible with other op-amp types such as the 725, 108A, OP-5, OP-7, LM11, and LM714 in applications where nulling is not required.

Due to their low offset voltage and excellent temperature stability, the CA3193 and CA3193A are ideal for precision applications such as thermocouple amplifiers, strain gauge bridge amplifiers, and high-gain filters. The two variants in the series are functionally identical, with the CA3193A offering tighter specifications for critical applications.

Features

• Low Input Offset Voltage (V_IO):
  • CA3193A: 200µV (Max)
  • CA3193: 500µV (Max)
• Low Input Offset Voltage Drift (ΔV_IO/ΔT):
  • CA3193A: 3µV/°C (Max)
  • CA3193: 5µV/°C (Max)
• Low Input Bias Current (I_IO) and Input Current (I_I)
• Low Input Offset Current Drift (ΔI_IO/ΔT): 150pA/°C (Max) for CA3193
• Low Input Current Drift (ΔI_I/ΔT): 3.7nA/°C (Max) for CA3193
• Internally Phase Compensated
• Gain Bandwidth Product: 1.2MHz
• Pin-Compatible with 741 Series Op-Amps

Applications

The CA3193 and CA3193A are versatile amplifiers suitable for a wide range of precision analog applications, including:

• Thermocouple Preamplifiers
• Strain Gauge Bridge Amplifiers
• Summing Amplifiers
• Differential Amplifiers
• Bilateral Current Sources
• Log Amplifiers
• Differential Voltmeters
• Precision Voltage References
• Active Filters
• Buffers
• Integrators
• Sample-and-Hold Circuits
• Low-Frequency Filters

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V_S): ±18V
• Input Voltage Range: ±15V
• Differential Input Voltage: ±30V
• Operating Temperature Range: -55°C to +125°C
• Storage Temperature Range: -65°C to +150°C

Key Performance Specifications (Typical @ 25°C, V_S = ±15V)

• Input Offset Voltage (V_IO):
  • CA3193A: 50µV
  • CA3193: 150µV
• Input Bias Current (I_B): 30nA
• Input Offset Current (I_IO): 5nA
• Common Mode Rejection Ratio (CMRR): 100dB
• Power Supply Rejection Ratio (PSRR): 96dB
• Open-Loop Gain (A_VOL): 120dB
• Slew Rate: 0.5V/µs
• Quiescent Current: 2.5mA

Package Information

The CA3193 and CA3193A are available in multiple package options to suit different application requirements:

• 8-Pin Metal Can (TO-99): Hermetically sealed package for high-reliability applications
• 8-Pin Ceramic DIP: High-temperature performance package
• 8-Pin Plastic DIP: Standard through-hole package for general applications
• 8-Pin SOIC (Surface Mount): Compact footprint for space-constrained designs

Pin Configuration (Standard 8-Pin DIP/SOIC)

• Pin 1: Offset Null
• Pin 2: Inverting Input (-)
• Pin 3: Non-Inverting Input (+)
• Pin 4: V_EE (Negative Supply)
• Pin 5: Offset Null
• Pin 6: Output
• Pin 7: V_CC (Positive Supply)
• Pin 8: NC (No Connection)

Design Considerations

When implementing the CA3193 or CA3193A in a circuit design, consider the following:

• The amplifiers are internally compensated and do not require external compensation components for most applications
• For lowest offset voltage, use the offset null pins (1 and 5) with a 10kΩ potentiometer
• Maintain proper power supply decoupling with 0.1µF ceramic capacitors close to the supply pins
• For high-precision applications, consider the CA3193A variant for its tighter specifications
• The amplifiers are sensitive to PCB layout; keep input traces short and properly shielded when handling low-level signals

Conclusion

The CA3193 and CA3193A operational amplifiers represent a significant advancement in precision analog design, combining the benefits of PMOS and bipolar technologies on a single chip. Their excellent temperature stability, low offset voltage, and high gain make them ideal for demanding instrumentation applications where conventional op-amps may fall short. The pin compatibility with industry-standard devices allows for easy upgrades in existing designs, while their superior performance characteristics enable new applications in precision measurement and control systems.