A Fully Automated Sweep Generator Measurement System – Take 4
It has been well over a decade since I first published my circuit for building your own automated sweep generator measurement system.1 That instrument, along with two further updates,2,3 relied on a personal computer (PC) with parallel port for control and readout functions. Clearly, an update is overdue.
The first three takes of my fully automated sweep measurement system perform three primary functions:
1. Repeat RF Sweep–The RF source repeatedly sweeps across a settable frequency range as a voltage output ramps between negative and positive limits to provide horizontal sweep for an oscilloscope that displays the response of a high-frequency logarithmic detector to the RF input through some circuit under test.
2. Single RF Sweep & Measure–The RF source sweeps one time across a settable frequency range as the instrument measures the voltage from a high-frequency logarithmic detector and provides the data for plotting.
3. Transfer Function–The voltage source sweeps one time across a settable voltage range as the instrument measures the responding voltage from a circuit under test and provides the data for plotting.
The RF output comes from a daughter card with an Analog Devices AD9851 direct digital synthesis (DDS) chip or a daughter card with a Silicon Labs Si570 programmable crystal oscillator (PXO). A logarithmic detector measures RF signal level to provide a very wide dynamic range of RF signal level measurement. The voltage out comes from a digital-to-analog
