Archive for December 25, 2015

Keysight EXA Signal Analyzer / Spectrum Analyzer Review, Teardown & Experiments

In this episode Shahriar reviews the Keysight EXA Signal Analyzer / Spectrum Analyzer (N9010A). The X-Series Signal Analyzers and Spectrum Analyzers from Keysight are compared against each other. The EXA is a general purpose spectrum analyzer with extensive applications.

The full instrument block diagram is presented with focus on various signal paths and frequency planning. Several of internal modules (RF Front-End, Digital Baseband Processor and LO Synthesizer) are also presented and compared with the block diagram. In order to examine the instrument’s capabilities in a real-world situation, a complete superheterodyne wireless transceiver with a sliding-IF receiver is designed and examined. Each component in the system (LNA, mixer, PLL, etc.) is individually characterized by using the EXA Signal Analyzer. The complete system measurements are also presented.

Various chapters in the video can be found at the following time marks:

  • Introduction (0:08)
  • X-Series model comparison (0:50)
  • EXA block diagrams and principle of operation (4:27)
  • Various board teardown and examination (20:39)
  • Instrument front/back panel overview (37:05)
  • Wireless experiment setup description (43:22)
  • Doubler characterization with EXG as the tracking generator (45:31)
  • LNA and mixer gain and NF by using Noise Figure personality (57:31)
  • Signal-Hound VSG25A I/Q modulator characterization, OBW, ACPR, TOI (1:08:57)
  • PLL characterization with Phase Noise personality (1:19:49)
  • Full transmitter measurement with Keysight VSA (1:26:08)
  • Full wireless link characterization with Keysight VSA (1:30:28)
  • Concluding remarks (1:37:21)

Tutorial on the Theory, Design and Characterization of a CMOS Transimpedance Amplifier

In this episode, Shahriar and Shayan discuss the design and characterization of a deceptively simple CMOS inverter-based transimpedance amplifier. The the large and small signal behavior of the CMOS inverter is discussed and measured using the Keithley 2450 and 2460 source meters. The transient response is also measured using a Keysight MSO-S series oscilloscope.

The small signal gain of the circuit is calculated from small signal parameters which are extracted directly by measuring the devices I/V characteristics. The NMOS/PMOS devices used are from an ADL1105 quad-discrete transistor IC. Through the use of a shunt-shunt feedback, the CMOS amplifiers is converted to a transimpedance amplifier which is capable of amplifying the current from a photo-detector diode by a gain of 30kV/A. The feedback theory is used to calculate the gain of the amplifier. The slides for this tutorial can be downloaded here.

Tutorial and Experiments with ESP8266 SoC, Blynk App, Arduino and Internet of Things (IoT)

In this episode Shahriar explores the functionality of the popular ESP8266 SoC chip. This IC incorporates a full ISM radio as well as the physical/MAC layer for 802.11b/g/n network communication. Furthermore it includes a uC core for code execution making it a low-cost candidate for Internet of Thing applications. This video uses a Sparkfun Thing evaluation board which also includes a LiPo batter charger, voltage regular, flash memory and all the I/O pins which are accessible to the user. The block diagram of the ESP8266 is reviewed as well as the schematic of the complete Sparkfun Thing board.

By using an Arduino library and the Blynk iOS application, a cell phone and the ESP8266 can simultaneously communicate with a server running the Blynk application and transfer data between the application and the module. In this demo various components such as NeoPixel (WS2812), OneWire temperature sensor and battery monitoring functionality are implemented. The code is available here.

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