Tag Archive for Digital

Overview of the Tektronix MSO58 8-Channel 6.25GS/s 2GHz Mixed-Signal Oscilloscope

In this short episode Shahriar demonstrates an overview of the new Tektronix MSO58 8-Channel 6.25GS/s 2GHz Mixed-Signal Oscilloscope with up to 64-Bits of digital channels. The scope features independent ADC, data acquisition and memory per channel as well as FlexChannel architecture which allows each channel to act as either a 2GHz analog channel or an 8-Bit digital channel. The scope also features a brand new GUI interface on an HD 15.6″ display with significant performance enhancement and touch interface optimizations. A full review of the instrument will be provided in the future.

Tektronix MDO4104C-6 Mixed Domain Oscilloscope (MDO4000C) Review, Teardown and Experiments

In this episode Shahriar performs a full review on the Tektronix MDO4000C series mixed domain oscilloscope, particularly model MDO4104C-6. The MDO4000C combines up to six instruments including a function generator and a built-in spectrum analyzer. Unlike any other instrument, it can synchronize RF, analog and digital channels. These correlated measurements provide insight into difficult to find problems particularly intermittent events.

This review begins with a comparison between the MDO4000B and MDO4000C instruments. The full review of the MDO4000B can be viewed here. All experiments demonstrated in the MDO4000B review are also relevant to the MDO4000C instrument.

The teardown of the instrument reveals a multi-board construction where the ADCs, FPGAs, application processor and memory are on the main system board. A complete analysis of the entire system is presented including the operation of the RF module.

In order to demonstrate the instrument’s capabilities, an encrypted frequency hopping transmitter system is analyzed. The system exhibits various problems such as high BER, low SFDR, poor phase-noise and EVM. The MDO4000C is used to perform advanced measurements across analog, digital and RF domain to track and resolve these problem. The complete block diagram of the experiment can be found 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.

Tutorial on the Design & Implementation of an FPGA RGB LED Matrix Driver

In this episode Shahriar and Timo demonstrate the design methodology of an FPGA based 32×32 RGB LED matrix driver. Timo has kindly devoted some of his time to describe the block diagram and the thought process which goes into designing this type of FPGA display driver. The various components of the overall system (PLL, UART, and Display Controller) are shown along with the simulation data. The outputs of the Spartan-6 FPGA board are then measured using a Keysight S-Series oscilloscope. The design of the RGB matrix is also demonstrated using a custom clock interface sent wirelessly to the unit via Bluetooth. All the FPGA design files can be downloaded here.

Tutorial on the Theory, Design and Characterization of Delta-Sigma Analog to Digital Converters

In this episode Shahriar explores the world of Delta-Sigma modulators with emphasis on a Delta-Sigma Analog to Digital Converter (ADC). The basic concepts of analog to digital conversion is presented, particularly with respect to quantization noise spectral shape and power density. Next, oversampling ADCs are presented to demonstrate the possibility of increasing SQNR (ENOB) through manipulation of quantization noise spectrum.

Due to the practical limitations of high oversampling ratios, delta-sigma modulations is explored. The principle operation behind delta-sigma ADCs is presented with detailed explanation on noise shaping, filtering and decimation. The signal and noise transfer functions for a 1st order and 2nd order delta-sigma ADC are derived. Finally, as a practical example, a 2nd order delta-sigma ADC based on a 1-bit quantizer is presented. The ADC uses two Miller integrator op-amps, one comparator and a D-Type flip-flop. The complete measurement of this delta-sigma ADC is presented. The impact of over sampling ration, op-amp linearity and input signal bandwidth is presented. The slides for this video can be downloaded here.

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