After seeing Dennis Feucht's excellent series on the design of a Z meter on a chip (see a list of his blogs here), I decided another piece of test equipment we need is an oscilloscope on a chip. I won't go into an analysis as detailed as the one that Feucht produced. Instead, allow me to provide an overview in order to evaluate the practicality of such test equipment on an IC by looking at the subsystems required.
To build a 'scope, you will need one or multiple high-speed ADCs, one per vertical input channel — so probably two or four. In front of the ADC, you need one or more gain stages and switchable filter networks to set the channel bandwidth. So far, this can be done at the chip level. You will also need a switchable attenuator, but at least part of that will likely be impractical to integrate because it will be subjected to high voltages. I don't like to mix low-voltage, low leakage, high speed device processes with high-voltage processes. But at some point, this may become practical.
You will need an accurate time base to mimic the function of the horizontal sweep — except that there really isn't a horizontal sweep like in a CRT (cathode ray tube) based 'scope. All you need to have is large amounts of digital memory and processing to take the values from the ADC and light up a pixel at the right place on the LCD or flat panel display. So with enough square millimeters of silicon, this is practical.
On the plus side, since the display is not a CRT, you don't need amplifier circuitry operating at a few hundred volts for the vertical and horizontal deflection plates, or an anode supply operating at a few thousand volts.
The trigger function should be straightforward. Look for a certain voltage (trigger-point). Then, perhaps, look for a certain rate of change of that voltage. Easy.
You will need the capability to accept input from the user, which means a bunch of I/O for the usual soft keys. So that means an MCU, an FPGA, and lots of port bits.
All of the above represents the important stuff, but it all seems practical. You could add additional functionality on the chip as desired. This could include power supply supervisory circuitry and touch screen interface.
Have you worked on 'scope designs before? What have I overlooked in this review?