Select resolution from 8 to 16 bits in a USB oscilloscope

May 13, 2013 // By Graham Prophet
Pico Technology has used reconfigurable ADC technology to offer a choice of resolutions from 8 to 16 bits in a single product; the company says this is the first time this facility has been popssible in an oscilloscope.

Most digital oscilloscopes gain their high sampling rates by interleaving multiple 8-bit ADCs. Pico asserts that, despite careful design, the interleaving process introduces errors that always make the dynamic performance worse than the performance of the individual ADC cores.

PicoScope 5000 Series scopes have a significantly different architecture in which multiple high-resolution ADCs can be applied to the input channels in different series and parallel combinations to boost either the sampling rate or the resolution.

In series mode, the ADCs are interleaved to provide 1 Gsample/sec at 8 bits. Interleaving reduces the performance of the ADCs, but the resulting dynamic range (60 dB SFDR) is still much better than oscilloscopes that interleave 8-bit ADCs. This mode can also provide 500 Msamples/sec at 12 bits resolution.

In parallel mode, multiple ADCs are sampled in-phase on each channel to increase the resolution and dynamic performance. Resolution is increased to 14 bits at 125 Msamples/sec per channel (70 dB SFDR). If only two channels are required then resolution can be increased to 15 bits, and in single-channel mode all the ADCs are combined to give a 16-bit mode at 62.5 Msamples/sec.

Pico has over 20 years’ experience in the design of high-resolution oscilloscopes but says that developing a new analogue front end to support an oscilloscope that can be switched between different resolutions was a significant challenge. Careful attention was required to support the high-resolution modes (with low noise, low distortion and bandwidth flatness) while maintaining the bandwidth, slew rate and pulse response necessary for the faster 8-bit mode.

As well as flexible resolution, these oscilloscopes have deep memory buffers of up to 512 Msamples to allow long captures at high sampling rates. They also include, as standard, advanced software features such as serial decoding, mask limit testing and segmented memory.

PicoScope 5000 Series Flexible Resolution Oscilloscopes are available now from Pico distributors worldwide and from Prices range from €846/£699/$1153 for