In this episode Shahriar presents the inner workings of an Agilent 86109B optical/electrical DCA-X oscilloscope module. This particular model offers up to 50GHz of electrical bandwidth and an optical input capable of receiving up to 40Gb/s data rates. The differences between a real-time and sub-sampling oscilloscopes are presented with focus on ADC resolution, signal periodicity requirements and input bandwidth. The block diagram of the module as well as a sub-sampling oscilloscope is also presented.
The teardown of the module shows various components such as samplers, O/E conversion block, impulse generator as well as a step-recovery diode driver. I/O interfaces as well as various analog blocks are also shown. Several modules are further disassembled to observe the inner semiconductor designs under the microscope.
In this episode Shahriar demonstrates the architecture and design considerations for high-power microwave amplifiers. Two architectures are presented, the balanced and Doherty microwave amplifiers. The block diagram, circuit properties and the pros/cons of each architecture are presented. Two available high-power amplifiers modules for cellular applications are also examined. The PCBs show an implementation instance of each amplifier type capable of delivering 100W of RF power. The datasheet of various components as well as an overall system structure are also presented.
In this episode Shahriar repairs an Agilent 54845A oscilloscope with an intermittent failure. The instrument occasionally fails self-calibration and the displayed waveform shows undesired spurious activities. The teardown of the instrument reveals customized front-end section coupled into a ceramic-substrate ADC ASIC designed by Agilent. The packaged ADCs are placed in sockets. The ICs are removed and the ceramic carrier is cleaned; this resolves the intermittent problem with the channels. The architecture of the scope is also presented. The functionality of the scope is verified through self-calibration, self-test and measurement of various waveform.
In this episode Shahriar repairs an Agilent E7495B 2.7GHz base-station test set capable of VSWR measurements as well as spectrum analysis. This particular unit is well equipped with many options however does not power on. A full teardown of the instrument reveals a faulty DC power conditioning module. The input filtering capacitor has failed. After component replacement, the unit is re-assembled. The functionality of the instrument is verified as well as a few quick experiments demonstrating various options.
In this short episode Shahriar upgrades the recently repaired Fluke PM6680B with a new OCXO design by Dan Watson. The design of the module is examined as well various considerations for providing ultra clean 10MHz reference for instrumentation. After module installation the unit functionality is verified. More information about the module is available here and here.
The Signal Path (TSP) is an electrical engineering video blog for industry professionals, students and hobbyists. TSP is a non-for-profit website dedicated to provide free education spanning a wide range of electrical engineering topics. Equipment reviews, tutorials and repair videos are posted regularly.