Current waveform analyser supports up to 200MHz

Many devices these days have currents that keep on shifting, especially when a semiconductor or system changes state. Mobile phones, in particular, draw more current when a call is made or when Wi-Fi is turned on. In addition, digital circuits need more current when switching states than when it is idle.

The most common way of looking at current is either with an oscilloscope connected across a shunt resistor or with a current probe around a wire or cable. You have to configure the oscilloscope to display in amperes or calculate the current yourself. But, you often have to measure small currents or small changes in current. With Keysight Technologies' CX3000 device-current waveform analyser, you get up to 200MHz bandwidth, 14bit or 16bit resolution, and system noise low enough to measure the small amounts of current drawn by today's devices, stated the company. The measurement resolution of 14 or 16bits depends on the bandwidth you need. At 16bits, you get 100MHz, and at 14bits, 200MHz. The CX3000 comes in two models, two-channel and four-channel.

Figure 1: The CX3000 comes in two two-channel and four-channel versions, but all other features are the same in both models.

To measure current, you insert a current sensor into the CX3000 and connect one of several sensor heads between the sensor and circuit-under-test. You connect the sensor head in series with your circuit's current flow. In the figure below, the CX1101A sensor head lets you measure current from 40nA to 10A with 100MHz bandwidth. Two other sensors are available when you need more channels or lower-level measurements. In addition to current probes, the CX3000 lets you connect up to eight logic inputs so you can correlate current draw to the states of digital signals.

Figure 2: Current sensor options let you chose sensitivity versus bandwidth.

Because the CX3000 functions like an oscilloscope, except that the vertical scale is in units of current, not voltage, you get many of the same functions that you get on a standard oscilloscope. For example, you can draw a box around portions of the waveform to see it in greater detail. Should you need to look at a signal with two levels of detail, you can use the dual-channel current sensor. As shown below, you can see the same signal on different ranges. As you might expect, you can also view signals in the frequency domain.

Figure 3: Using a dual-current sensor, you can see the same waveform with different levels of vertical detail. (200mA and 2mA ranges shown)

Prices: CX3322A (two-channel) ₹22.30 lakh ($33,000); CX3324A (four-channel) ₹27.70 lakh ($41,000). Current sensors range in price from ₹3.24 lakh-₹4.66 lakh ($4,800 to $6,900).

- Martin Rowe
  EDN