In this episode Shahriar reviews and demos the second revision of the industry’s first Mixed Domain Oscilloscope from Tektronix. The MDO4000B series offers improved signal integrity and performance. The reviewed model is a MDO4104B-6 which offers 16-Channel Logic Analyzer, 4-Channel Oscilloscope with 1GHz of analog bandwidth as well a 6GHz Spectrum Analyzer with greater than 1GHz of instantaneous capture bandwidth with 65dB of dynamic range.
After an overview of the instrument’s interfaces and built quality, the block diagram and principle operation of the instrument is explained. The time-correlated digital, analog and RF capturing capability is described and its advantages for debugging complex mixed-domain systems is explored. Instrument probes, accessories and various modules are also presented.
The instrument is used to measure an ultra-pure single-tone signal at various frequencies for THD, SFDR and dynamic range measurements. For the main demonstration, a complete I/Q modulator system prototype is presented. The prototype includes a Maxim MAX2721 modulator, external PA, antenna diversity switch SW-277, digital control circuitry, power-grid DC-DC converters, external step attenuators, an Agilent E4342B synthesizer for LO generation and an Agilent N6020A arbitrary waveform generator for baseband signal generation. The Tektronix MDO is used to monitor RF, baseband, digital and power-supply analog waveforms. The system includes an array of problems including intermittent spurious tones, power supply dependent spectral noise, antenna switching glitches and 256-QAM constellation imperfections. The MDO is used to analyze, measure and solve all system problems. Tektronix SignalVu is used to analyze the system performance. As a final experiment, the MDO is used to demodulate a 1GHz bandwidth 32-QAM 500MS/s signal centered at a 3GHz carrier. The experiment documents can be downloaded here.