You will need an infinite sample-and-hold system, which will consist of a D/A, digital storage (memory) and an A/D. You will probably need some sort of a microcontroller/FPGA to implement the digital storage, and to implement interfaces for the D/A and A/D. Depending on the accuracy you require, you might need to implement serial interface data converters. I used a similar circuit for a sensor application, and ordered 16 bit serial interface data converter samples from TI. Only problem is that its hard to find high resolution data converters in DIP, they mostly come in surface-mount.