A two-step tuning process for resistors and capacitors in an integrated circuit is described. In the first step of the tuning process, an on-chip adjustable resistor is tuned based on an external resistor to obtain a tuned resistor. The value of the tuned resistor is accurate to within a target percentage determined by the external resistor and the design of the adjustable resistor. In the second step, an adjustable capacitor is tuned based on the tuned resistor and an accurate clock to obtain a tuned capacitor having an accurate value. The adjustable capacitor may be tuned such that an RC time constant for the tuned resistor and the tune capacitor is accurate to within a target percentage determined by the accurate clock and the design of the adjustable capacitor. The resistors and capacitors of other circuits on the integrated circuit may be adjusted based on the tuned resistor and the tuned capacitor, respectively.