These days the term of firmware can only be used for very small devices. This is because we have more memory, flash and computation ability in tiny footprints. So even a mini gadget can have a Tiny OS sometimes even a Virtual Machine. What is a VM it is is a OS in a OS. Java, .Net.
Time-interleaved Analog-to-digital Converters

TIADCs and TI-ADCs an Article by Dr. Christian Vogel.
"The idea of a time-interleaved ADC (TIADC) is to use a system of M parallel channels, which alternately take one sample (time-interleaved sampling). Thereby, the sampling frequency of one channel does not need to fulfill the Nyquist criterion; however, when in the digital domain all samples are merged into one output sequence the overall sampling frequency fulfills the Nyquist criterion"
The Designer's Guide Community - A Guide to Simulation & Modeling for Analog & RF Circuit Designers
A Site where analog, mixed-signal and RF circuit designers come to learn about simulation, modeling and design. There are a number of very practical papers on simulation and modeling on the Analysis, Modeling, and Theory pages. A collection of useful example models can be found on the Verilog-AMS page.
Designing Analog Chips by Hans Camenzind
Hans Camenzind book on Analog CMOS design is a good reference for students and covers Power Electronic concepts like Switching Regulators and Low Drop-Out Regulators. The Delta-Sigma Converter A/D and Zero-Crossing Detectors on Mixed Design. Communications circuits like Timers and Oscillators . Phase-Locked Loops and Filters too.