We propose a threshold trimming based design of a CMOS operational amplifier (op-amp) whose specifications are varied over a wide range through a continuous and independent programming procedure. The programmable parameters include gain, gain-bandwidth, slew rate, input/output range and offset voltage. Observable behavior of op-amp is linked to threshold voltage (V_T) of constituent mosfets as explicit equations. An algorithm is proposed to enable fine and independent variation of specifications by trimming appropriate threshold voltages . As V_T can be trimmed on-chip using floating gate mosfets, it is proposed that this design methodology will enable field programmability in analog ICs. The circuit has been simulated using TSpice7 with BSIM3 level 49 spice model for 0.35? CMOS process. It is expected that this inbuilt field programmability will lead to high precision classification yields, reduce design time and costs.