Design and Implementation of Programmable Analog Board

Abstract

Prototyping of analog circuits is hair stretching work, and often get’s complicated because one has to work with breadboard. To eliminate bread boarding of big digital systems, FPGAs were developed over the past years for prototyping purposes. We have come up with similar thing for analog world. It’s like FPGA, but instead of digital it will create analog circuits like integrator, differentiator, adder based on coding. We have one plan to make it possible. FPGAs use RTL coding like VHDL/verilog and has their own s/w which converts coding to circuit net list and which gets implemented in FPGAs, now at this stage we don’t have that much knowledge to develop our own synthesizer s/w, hence we’ll use following plan. We will have OP-AMPs in circuit, and passive components which has capability to change it’s value based on programming. For resisters we use something known as digital POTs and for capacitors NCD2100 which is digital programmable variable capacitor. We’ll have interconnection between all of them via FETs, which will act as programmable switches. Now for programming, one has to write commands, which will be decoded by ASCII codes and accordingly switch matrix is programmed to form desired circuit. There is digital circuit which accepts ASCII bits and programs solid state switches, and with this one can implement amps, integrator, differentiators, adders, instrument amplifiers and combination of all above. Application of this thing can be found in prototyping, educational purposes and implementation of PID controllers.