IUF - Current to Frequency/Current to Voltage Converter


  • Converts very low currents to frequency or to voltage with a linearity better than 0.3% for the frequency output, better than 0.1% for the voltage output
  • High sensitivity - up to 25 pA/mV voltage output or 25 pA/kHz frequency output
  • Three models ACUF4-1, ACUF4-2 and ACUF4-3 offer different input sensitivity
  • Low noise design with very low leakage current and wide dynamic range
  • 50 nA to 1000 nA full scale current range
  • Pulse frequency (TTL) and voltage output, optical pulse output

The IUF-Series Current-to-Frequency and Current-to- Voltage converters is a compact device that can be mounted close to the signal source such as a Faraday Cup, Ion-Chambers, etc. and can transmit the voltage or frequency output to such devices as transient recorders, ADC's, digital volt meters (DVM) or multiscalers. The optical output enables the user to bridge large differences of voltage levels. A fiber optical cable and receiver is

included with every IUF module. Either positive or negative inputs are accepted (bipolar inputs only for voltage output). The output voltage or frequency is directly proportional to the input signal. By counting the output pulses per unit time, one gets the high resolution current information. Integration of the input signal may be obtained over the counting duration which gives the total charge accumulated. A very high (2 MHz full scale) output frequency provides exceptional resolution at short counting periods. The IUF models can be used as a digital current integrator. A typical application is a beam current digitizer.

Dimensions, Cables & Connectors:
DIMENSIONS: 160 x 54 x 28 mm
WEIGHT: 280 g
VOLTAGE-out Lemo 00
TEST-in: Lemo 00
Frequency-out: Lemo 00 (signal, 50 Ohm)
Frequency-out: ST-connector (optical)
Fibre optic cable: 62.5/125 um
POWER-in Lemo 0 (304)

DIMENSIONS: 60 x 35 x 20 mm
WEIGHT: 50 g
Input FOC: ST connector
Output-TTL (50 Ohm): BNC

for IUF
Input: 90 ... 230V AC
Output: 24V / 0.4A
Connector: Lemo 0 (304)
Weight: 120 g
for Fibre Optic Cable Converter
Input: 90 ... 230V AC
Output: 7.5V / 0.8A
Connector: 2.1 x 5 mm

Fibre optic cable: 62.5/125 um
Outer diameter: 2.8 mm FRNC
Connectors: ST
Length: 10 m

Model Order No.
Each model is shipped including: two Power Supplies, Fibre Optic Cable Receiver and 10 m Fibre Optic Cable

Model ACUF4-1 ACUF4-2 ACUF4-3
Jumper Position 1 (neg) 2 (pos) 1 (neg) 2 (pos) 1 (neg) 2 (pos)
R feedback 10 MOhm 50 MOhm 100 MOhm
C fb 2.7 pF 2.7 pF 2.7 pF
Time constant 37 μs 185 μs 370 μs
Input leakage current (typ) 1 pA
Frequency output:
Current range: 0 nA to -1000 nA +500 nA -200 nA +100 nA -100 nA +50 nA
Frequency sensitivity -500 pA/kHz +250 pA/kHz -100 pA/kHz +50 pA/kHz -50 pA/kHz +25 pA/kHz
Output frequency range 0 to 2 MHz
Linearity error 0,3% max
FS Current accuracy + -1%
Test input Freq. converter 0...10 V
Offset Freq. Adj. Range 0...30 kHz
FS Freq. Adj. Range 1,95...2,048 MHz
Voltage output: -5 to +10 V
Current range: from +500 nA -250 nA +100 nA -50 nA +50 nA -25 nA
to -1000 nA +500 nA -200 nA +100 nA -100 nA +50 nA
Sensitivity Volt -100 nA/V +50 nA/V -20 nA/V +10 nA/V -10 nA/V +5 nA/V
Noise Voltage (output, typ) 0.2 mV rms 0.4 mV rms 0.3 mV rms 0.6 mV rms 0.5 mV rms 1.0 mV rms
Noise Voltage (Ci=450 pF) 0.4 mV rms 0.8 mV rms 0.6 mV rms 1.2 mV rms 0.9 mV rms 1.8 mV rms
(bandwidth 0,1..10000Hz)
Offset Voltage (max) 0.8 mV 1.6 mV 0.8 mV 1.6 mV 0.8 mV 1.6 mV
Linearity error 0,1% max
Power supply +22 to +26 V @ 100 mA
For high resolution signal recording or signal-averaging the IUF models can be used as a front end of a FAST ComTec multichannel scaler such as the Model P7882 or the Model MS-12 Multi-Input Scaler board.