Analog-circuit designs have fundamentally different architectures from those of processor, FPGA, and PLD designs. Once you implement the circuit topology and parameters, the circuit’s signal-processing function is relatively fixed. Sure, some functional blocks exist, such as filters, in which you can digitally adjust cutoff frequency, roll-off, and other factors by varying the clock (for switched-capacitor designs) or adjusting circuit factors via DACs, but these examples are the exceptions. Most designs are fixed in their functions and nearly fixed in their performance. Read the rest of this entry »