I had a great time as a guest of The Amp Hour. We talked about everything from device physics to circuit design into the mm-wave frequencies and beyond. Although this interview took place a short while ago, I thought it would be beneficial to also have a link here at The Signal Path. Also, don’t forget to listen to the many great episodes of The Amp Hour. The link to my interview can be found here.
In this episode Shahriar does an extensive review and teardown of the Keysight (Agilent) MSO-S Series 10-bit 20GS/s Oscilloscope. This scope supports bandwidths up to 8GHz and 400M points of memory per channel. With hardware 10-bit ADCs as well as an ultra low-noise front-end, this scope offers an impressive dynamic range on all four channels. All scope features are software upgradable.
The teardown consists of a close look at the acquisition board and the system blocks diagram. Various elements such as the ADC structure, FPGAs, memory and the time-base are all examines. The scope offers a +/-12ppb time-base with a 100fs jitter noise floor. Some basic performance measurements are also presented such as noise and SFDR.
The wireless experiment shows the performance of the scope in demodulating very low-power signals on an RF carrier. A -75dBm 2.5GHs QPSK signal can be demodulated by the scope. The instrument can also demodulate a 16QAM signal in presence of an interfering signal which is 44dB higher in signal power. All demodulation experiments are performed using the Keysight VSA.
The backplane experiments demonstrate the scope’s capability to perform jitter and noise analysis on multi-gigabit serial links. The built-in equalization software suites are used to find the FFE coefficients and those coefficients are used to perform hardware equalization in an FPGA communication link.
In this episode Shahriar attempts a repair of an Agilent E3642A DC Power Supply which is completely non-responsive. After presenting a teardown of the power supply, the GPIB interface is used to verify the functionality of the power supply. The problem is traced to the main display unit which communicated with the main power supply via a serial interface.
After disassembly of the display, it is revealed that the entire unit has suffered a catastrophic failure due to the VFD display drive IC. All components must be individually removed and replaced. Unfortunately the main processor is a Mask ROM IC version (80C51) and cannot be sourced. Can you help Shahriar find a replacement part?
In this episode Shahriar repairs an Agilent E4433B ESG-D Synthesized Signal Generator. This 4GHz unit shows the “UNLEVEL” error for all frequencies and at all output power levels. After a close look at the system block diagram the fault is traced to the main Output RF board.
The Output RF board is equipped with various amplifiers, electronic attenuators, I/Q mixers, heterodyne paths and final PA. By using soldered SMA cables to various points in the signal path, the fault is traced to an internal amplifier chain which is likely made of a MESFET or JFET transistor. Since this part is obsolete, an RFMD GaAs hybrid amplifier is used in its place. The biasing network and matching networks need to be modified to accommodate this change. The repaired unit is then verified for functionality and performance by measuring a QAM constellation output signal.
In this episode Shahriar compares the performance and features of the Siglent SDG5162 and Rigol DG4162 Arbitrary Waveform Generators. Siglent has recently opened a new North America office which would certainly help them bring their instruments to the US more quickly and provide better local customer and sale support.
The Siglent SDG5000 teardown is presented. Aside from various GUI features of these two units, the THD, phase noise and maximum output power of each unit is measured. The ability of the Siglent generator to produce 12ns pulse width independent of the output frequency is also presented with some practical applications. Finally the Easy Wave application us is used to generate some custom waveforms.