My appologies.!.. Altough I said ADC, what actually I mean an ADC board,
not necessary single chip.
My corrected question is;
I'm looking for 12-16bit ADC Board with 4MHz sampling rate capable of
storing 4K samples, with USB interface to transfer data to a PC.
A 12-16 bit ADC with 4 Mhz sampling rate requires a minimum throughput of 48
Mb/s, and a maximum of 64 Mb/s. This means you must have a Hi-Speed USB 2.0
IC, which is capable of the theoretical maximum of 480 Mb/s.
One candidate is SMSC's GT3200. It has a 16-bit parallel interface, thus it
is possible to interface it with any modern microprocessor. For the ADC
unit, I'd look at Analog Device's ADC selection matrix. They have at least a
16-bit 65 MSPS (Million samples per second) device and a 16-bit 3 MSPS
device. If your sampling rate of 4 Mhz is absolute, the 65 MSPS is the
nearest suitable 16-bit one. The interface is parallel, thus it would be
directly compatible with the GT3200.
If a lower sampling accuracy is enough, AD also offers a 12-bit and 14-bit
10 MSPS devices, both with parallel interface. The upper 4(2) bits of the
USB unit could be used for signalling, if necessary.
I have only experience with the AD's ADC units, and they've been positive
experiences. Dunno about the GT3200, but you could try checking them out.
-Antti Keskinen