90 dB Logarithmic Amplifier


  • High-speed logarithmic signal compression
  • High dynamic range - up to 90 dB
  • Selectable input coupling
  • Selectable input impedance
  • Compact size
  • Input protection for high-voltage transients


LOGAMP3 is a stand-alone logarithmic amplifier (log amp). It provides high-speed logarithmic signal compression from micro volts to volts with exceptional linearity. Both positive and negative information may be processed over a wide range of duty cycles. The diagram below shows the response chart of the log amp. The weaker signals get higher magnification than the stronger signals. The output signal from the log amp can be further processed by the hardware on a receiver board.

LOGAMP3 is widely used for ultrasonic testing on high attenuation materials which require high dynamic range of signals on one scope screen without using high resolution ADC instrument. Applications in the ultrasonic testing include composite material evaluation, corrosion mapping with rough surfaces, small flaw detections, and some tests with wide range of signal amplitude. Other applications include LIDAR, lasers, and electro-optiics.


Input Impedance 200 or 50 ohms switch selectable
Input Coupling AC or DC switch selectable
Input Range 0.0001 to 10 Vp-p
Input Noise 16 micro volts typical
Pulse Response Rise time: 12 ns (DC-30 MHz)
Fall time: 15 ns typical
Operating Temperature 0ᵒC to 50ᵒC
Output Single-ended
Noise: 7mVRMS typical
Load: >=50 ohms
Slope: 29 mV/dB typical
Polarity Non-Inverting
Linearity +/-1 dB
Power 12VAC/100mA from an AC/AC adapter
Dimensions 4.5"x2.7"x1.2" (107mm x 70mm x 30mm)/td>