DHPVA 100/200 MHz Wideband Voltage Amplifier

Choose the model according to the highest signal frequency and shortest edge time that the measurement must retain. The DHPVA-101 provides 100 MHz full bandwidth with a 3.5 ns rise/fall time, while its reduced mode provides 10 MHz and 35 ns. The DHPVA-201 extends these values to 200 MHz and 1.8 ns, with a 20 MHz reduced mode giving an 18 ns response. Both models otherwise share the same gain range, input noise, drift, 50 Ω signal path and control arrangement. The 200 MHz version is therefore appropriate when the additional bandwidth is required, whereas the 100 MHz model covers systems whose useful spectrum remains below that limit.

Select the lowest gain that gives adequate digitiser or oscilloscope resolution while keeping the amplifier output below its 2 Vpp linear range. The available 10, 20, 30, 40, 50 and 60 dB settings correspond to voltage gains of approximately ×3.16, ×10, ×31.6, ×100, ×316 and ×1,000. For example, a 10 mVpp input produces about 1 Vpp at 40 dB, while 50 dB would target approximately 3.16 Vpp and exceed the linear range. The usable input-signal envelope is about 100 µV to 300 mV, extending towards 10 µV when averaging is applied. Actual resolution at the lower end also depends on measurement bandwidth, source impedance and the required signal-to-noise ratio.

Gain-independent bandwidth means that changing sensitivity does not produce the usual large change in edge speed or frequency response. Bandwidth and rise/fall time remain within a maximum deviation of ±10% across the six gain settings, allowing measurements at different gains to be compared more directly. At full bandwidth, the nominal rise/fall times are 3.5 ns for the DHPVA-101 and 1.8 ns for the DHPVA-201. The reduced modes change these times to 35 ns and 18 ns respectively and use an approximately Bessel response. This lets the engineer retain full speed for fast transients or intentionally limit bandwidth when reduced integrated noise is more important.

Use DC coupling when the absolute signal level, slow variations or frequencies below 10 Hz must be measured. AC coupling introduces a 10 Hz lower cut-off, making it suitable when a DC component or slow baseline movement would otherwise consume output range. In DC mode, the input offset can be adjusted across −10 mV to +10 mV using the front control or an external voltage. The external ±10 V control range corresponds to ±10 mV of input-referred offset adjustment, while the input voltage drift is 0.3 µV/°C. The coupling choice should therefore be based on whether baseline information is required and how much offset can be tolerated within the selected gain and output range.

Yes, five opto-isolated digital inputs provide remote control of gain, coupling and bandwidth using TTL/CMOS-compatible levels. Logic low is defined from −0.8 to +0.8 V, while logic high is accepted from +1.8 to +12 V. Gain is coded through Pins 10 to 12, AC/DC coupling uses Pin 13 and the bandwidth mode uses Pin 14, with a stated gain-switching time of 5 ms. The remote bits operate by logical OR with the local switches, so the corresponding local control must first be placed in the required remote-compatible position. Mixed operation is also possible, allowing gain to remain under local control while bandwidth or coupling is managed by the test system.

The main input and output are both designed for a 50 Ω environment and use female BNC connectors. A 50 Ω RF cable and a 50 Ω receiving termination should be used when the specified bandwidth, pulse response and return-loss performance are required. At 100 MHz, the DHPVA-101 has input and output return losses of −31 dB and −35 dB respectively; at 200 MHz, the DHPVA-201 values are −22 dB and −30 dB. The separate monitor output also has a 50 Ω source impedance, but it is designed to drive a load of at least 1 MΩ. Terminating that monitor connection in 50 Ω would therefore reduce its available voltage and would not represent its intended operating condition.

The amplifier requires a regulated ±15 V supply through its three-pin power connector. Typical supply current is ±120 mA, although the maximum rating is ±400 mA depending on operating conditions. The specified operating temperature range is 0 °C to +50 °C, with storage permitted from −40 °C to +85 °C. One or both heat sinks may be removed only when the enclosure or rack provides an alternative thermal path below 2 K/W through suitable metal-to-metal contact. For an integrated system, the designer should therefore allow for supply headroom, connector access, airflow and a defined conductive cooling path before changing the standard heat-sink arrangement.