Whenever a semiconductor or system changes state, there’s a good chance that the current it draws will also change. A typical example is a cell phone, which draws more current when you make a call or turn on Wi-Fi. Digital circuits also need more current when switching states than when in idle states.
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’s CX3300 Device Current Waveform Analyzer, you get up to 200-MHz bandwidth, 14-bit or 16-bit resolution, and system noise low enough to measure the small amounts of current drawn by today’s devices. The CX3300 comes in two models: two-channel and four-channel.
To measure current, you insert a current sensor into the CX3300 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. The CX1101A current sensor lets you measure current from 40 nA to 10 A with 100-MHz bandwidth. Two other sensors are available when you need more channels or lower-level measurements. In addition to current probes, the CX3300 lets you connect up to eight logic inputs so that you can correlate current draw to the states of digital signals.
Because the CX3300 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.
Prices: CX3322A (two-channel) $33,000; CX3324A (four-channel) $41,000. Current sensors range in price from $4,800 to $6,900.
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