High-definition oscilloscopes provide better resolution at a higher bandwidth

When it comes to any kind of signal digitizing, you always face the tradeoff between bandwidth and resolution. Teledyne LeCroy’s HDO9000 series bridges the gap between its traditional 8-bit and 12-bit oscilloscopes, but its flexible architecture lets it find the best combination of resolution and sample rate. The HDO9000 line gives better resolution than attainable with 8 bits but with higher bandwidth than you get with their 12-bit cousins.

Teledyne LeCroy’s 10-bit technology even has its own name, dubbed HD1024, with models of 1-GHz, 2-GHz, 3-GHz, and 4-GHz maximum bandwidth. All bandwidths are available with MSO options. The HD1024 technology uses a combination of timing and ADC code offsets to achieve 9 or 10 bits from 8-bit, 5-Gsample/s ADCs. The acquisition system can take four samples at a time but does so only twice per clock period, resulting in 10 Gsamples/s. Each time you double the number of vertical samples, you gain an additional bit of resolution. That explains why you need four samples for each clock cycle, dropping the overall sample rate to 10 Gsamples/s. The same ADC code offset applies at 10 bits, just doubled from 9 bits. The entire bit-selection process occurs automatically, adapting to signal conditions.

Because of the HDO9000’s maximum bandwidth of 4 GHz, the 10 Gsamples/s still provides 2.5x oversampling. That satisfies the Nyquist criteria, making it possible for the oscilloscope to extrapolate the signal shape between samples. Oversampling improves timing resolution for models with lower bandwidths or at higher sampling rates (fewer bits).

If you need even more resolution, the HDO9000 can provide that, but you will pay for it in bandwidth. That’s because the oscilloscope uses signal processing to achieve 13.8 bits of vertical resolution. That process uses the common filtering technique of reducing bandwidth, which reduces noise.

While the additional bits let you see details that might go missing in 8-bit oscilloscopes, the HDO9000 series also gives you lots of analysis capabilities. Math tools include digital filters, tracks and trend, and demodulation. Signal analysis tools include eye diagrams and protocol decoding. The HDO9000 series also includes Teledyne LeCroy’s MAUI user interface.