High Speed Power Amplifier

High Voltage Amplifier PA120A
  • Bandwidth: DC-1.5MHz
  • Slew-Rate: 250V/µs
  • Load current: > 10AP
  • Offset: < 3mV
  • Sophisticated limiting and protection concept


  • Research
  • Development (in particular power electronics)
  • Pulse physics
  • Component testing
  • Quality assurance
  • Measurement and test engineering

PA120A is a high speed DC-coupled power amplifier featuring power bandwidth of 1.5MHz.

The output stage of PA120A provides output voltages ranging from -30V to +30V, whereas load currents of ±4A and peak load currents up to ±10A are available.

The amplifier comes with two input channels; their signals are added together. This allows e.g. for providing an AC-signal with a DC-offset. Another example would be superimposing of the wanted signal by a disturbing signal. Input resistance (50Ω / 10kΩ) as well as coupling mode (AC / GND / DC) and gain (x1 / x10) can be set for each input channel separately.

LED indicators at the inputs (LIMIT + / LIMIT -) signalise overmodulation of the input stage.

The power output stage is protected against overload and overtemperature.
The supply voltage of the output stage is varied depending on junction temperature of its transistors (Tj LIMIT + / Tj LIMIT -). This method allows for achieving high output currents even at small output voltages.

Monitoring of the junction temperature also makes a fast current limitation unnecessary, thus allowing for very high peak output currents (> 10A). If either the junction temperature exceeds 125°C (Tj OVER) or the maximum heatsink temperature is exceeded (Ths OVER), the output of the amplifier will be disconnected.

If the output voltage level exceeds its positive or negative limit, the appropriate output limit indicator LED lights up (LIMIT + / LIMIT -). The output voltage will be then reduced, preventing overmodulation of the power output stage.

Technical Specifications:
Parameter Symbol Min Typ Max Unit Comment
Absolut maximum ratings:
Input voltage (RI 10kΩ) VI10 -90 +90 VP
Input voltage (RI 50Ω) VI50 15 VRMS
Electrical characteristics:
Input voltage VI10-1 -30 +30 VP
(RI 10kΩ, GAIN x1)
Input voltage VI10-10 -3 +3 VP
(RI 10kΩ, GAIN x10)
Input voltage VI50-1 -30 +30 VP max. 15VRMS !!
(RI 50Ω, GAIN x1)
Input voltage VI50-10 -3 +3 VP
(RI 50Ω, GAIN x10)
Lower limiting frequency AC f (-3dB) 15 Hz
Output voltage VO -30 +30 VP RL≥7.5Ω, f≥10kHz
Load current IODC 2 2.2 A f=0Hz
Load current IOAC 4 4.5 AP f≥10kHz, square
Load current IOAC 6.3 7 AP f≥10kHz, sine
Pulsed load current IOP 10 20 AP tP≤20µs, D≤0,2
Output resistance RO 0.1
Output resistance Monitor Out ROM 51
Frequency response f (-3dB) 0…1.5 MHz RL=50Ω
Frequency response BW-LIMIT f (-3dB) 0…300 kHz RL=50Ω
Slew-Rate SR 200 250 V/µs RL=50Ω
Output offset voltage ΔVOO -3 1.5 +3 mV
Mains voltage VLINE 207 230 253 VAC
Mains frequency fLINE 45 50 65 Hz
Power consumption PLINE 25 300 W
Input current ILINE 1.6 A
Mains fuse T3.15A UL 248
Ambient temperature (operation) TAMB 0 20 35 °C
Storage temperature TS -25 +85 °C
Width W 470 mm
Height H 153 mm
Depth D 300 mm
Weight m 10.5 kg