1 Features
• Ultra-low input bias current:
– 20fA (tested max) at 25ºC, VS = 16V
– 20fA (tested max) at 85ºC, VS = 16V
– 75fA (tested max) at 85ºC, VS = 36V
• Ultra-low noise:
– 0.07fA/√Hz at 0.1Hz
– 15nV/√Hz at 1kHz
• High dc precision:
– ±5μV input offset voltage
– ±0.1μV/°C offset voltage drift
• Integrated high-precision guard buffer
• Wide bandwidth: 2.5MHz GBW
• Low quiescent current: 275μA
• Wide supply: ±2.25V to ±18V (4.5V to 36V)
• Rail-to-rail input and output
• Operating temperature range: –40ºC to +125ºC
• Industry-standard SOIC package with low leakage
pin out

2 Applications
• Electrochemical meter, pH meter
• Lab and field Instrumentation
• Mass spectrometer
• Ion chromatography (IC) instrument
• Spectrophotometer
• Electrometer
• Coulomb counting

3 Description
The OPA928 is a new generation, 36V, femtoampere
input bias, e-trim™ operational amplifier. This device
offers an ultra-low input bias current of 20fA (max)
across the entire industrial temperature range, −40ºC
to +85ºC. The OPA928 input bias performance is
tested at production at both temperatures.
The near-zero input bias is complemented by
outstanding dc precision and ac performance,
including rail-to-rail input and output, low offset
voltage (±5μV, typical), low offset drift (±0.1μV/°C,
typical), and ultra-low current noise (0.07fA/√Hz
at 0.1Hz). These features make the OPA928 an
excellent choice for low-light photodiode and high
source-impedance applications.
The OPA928 features an internal, high precision
guard buffer to protect high impedance input
traces from undesirable current leakage in sensitive
applications. The OPA928 packaging and pin out is
designed to support low-leakage circuit designs.
The OPA928 is the next generation OPA128.