Current to Voltage Converter

Calculate current to voltage converter circuits (transimpedance amplifiers). Design photodiode amplifiers, current sensors, and precision current measurement circuits.

Current to Voltage Converter (Transimpedance Amplifier)

                         Rf
    Iin ──┬─────/\/\/\─────┬─── Vout
          │               │
          │    ┌─────┐    │
          └────┤-    │    │
               │  Op │────┘
          ┌────┤+  Amp
          │    └─────┘
          │
         GND
         
    Vout = -Iin × Rf
    Gain = Rf (Transimpedance Gain in Ω)
mA
mV/mA
MHz
pF

About Current to Voltage Converters

Current to voltage converters (I-V converters or transimpedance amplifiers) convert current signals to voltage signals. They're essential for photodiode amplifiers, current sensing, and precision measurement applications.

Key Characteristics:

  • Virtual Short: Input voltage ≈ 0V (virtual ground)
  • High Input Impedance: Minimal loading of current source
  • Linear Response: Output proportional to input current
  • Bandwidth Limitation: Gain-bandwidth tradeoff

Design Considerations:

  • Stability: Compensation may be required
  • Noise: Johnson noise from feedback resistor
  • Bandwidth: Limited by feedback capacitance
  • Op-amp Selection: Low input bias current important

Op-amp Recommendations:

  • Low Noise: OPA627, LT1028, AD797
  • High Speed: THS4031, LMH6624, ADA4817
  • Low Bias Current: LMC6001, OPA128, ADA4530
  • General Purpose: TL072, LM358, OPA2134