Analog Devices introduces an electrometer-grade operational amplifier

     ADI, the world's leading provider of high-performance signal processing solutions, recently introduced the ADA4530-1 electrometer operational amplifier, a compact solution that ensures maximum accuracy and data repeatability across a wider temperature range for chemical analysis instruments, reducing overall material cost and design size. The ADA4530-1 op amp's success lies in its extremely low bias current, one-twentieth that of competing products, or even lower.

     This low bias current makes the ADA4530-1 ideal for connecting sensors that are sensitive to output load, such as photodiodes, as well as other high output impedance sensors commonly used in precision monitoring/analysis equipment, such as spectrophotometers, chromatographs, mass spectrometers, and measuring equipment for constant potential and constant current coulomb analysis. The new amplifiers can also be used as front-end amplifiers for picoammeter and coulommeter measurement systems, trans-resistance amplifiers for photodiode, ionization chamber and working electrode measurements, or high-impedance buffers for chemical and capacitive sensors.

     The ADA4530-1 operational amplifier has an input bias current of 250 fA at 125°C, one-twentieth that of its competitors, and drops to 20 fA at 85°C, one-fiftieth that of its competitors. In addition, the ADA4530-1 is the only operational amplifier capable of maintaining the same 20 fA input bias current from room temperature to 85°C, and the only amplifier in its class to pass comprehensive bias current production testing from room temperature to 125°C. Few of its closest competitors meet the 125°C standard, and none have been productively tested against bias currents at room temperature. Bias currents can prevent system designers from fully exploiting sensor sensitivity because they need to reserve some protective frequency bands for large variations in bias currents.

     The ADA4530-1 also features an on-chip protection buffer that tracks the input common-mode voltage and provides an output to drive the PCB protection ring or interconnect shielding, with the aim of reducing the impact of stray capacitance in the sensitive connector between the sensor and the amplifier. This simplifies sensor interface design and eliminates the need for customers to design a separate circuit for the desired output driver, which reduces design time, costs and PCB space.