oltage may vary between 3V and 6V. The task is to ensure that the center frequency, once set by lalser fuse, will not change within the predefined tem- perature and supply voltage range. Using the symbolic cir- cuit analysis tool Analog Insydes [2], the objective is to derive a formula for the center frequency of the filter as a The symbolic transfer function of the filter macro model (Figure 2) is derived by using Analog Insydes to set up the circuit equations from a netlist description and solve the equations for the output voltage in terms of the macro pa- rameters and the input voltage: