techniques are also called "zero-drift" amplifiers (because there is no drift in input offset voltage with time and temperature). Related techniques that also give these zero-drift advantages are auto-zero and chopper-stabilized amplifiers. Auto-zero amplifiers use a secondary auxiliary amplifier to correct the input offset voltage of a main amplifier. Chopper-stabilized amplifiers use a combination of auto-zero and chopper techniques to give some excellent DC precision specifications. Some example chopper and auto-zero amplifiers are LTC2050, MAX4238/MAX4239 and OPA333. Formulas Take a general step-up chopper with voltage source which is in series with the inductor , diode and the load with average voltage . The chopper switch would be in parallel with the series diode and load. Whenever the chopper switch is on, the output is shorted. Using Kirchhoff Voltage Law in determining inductor voltage, and taking the average current within the turn-off time, where is the time were a load voltage is present and the change current with respect to . Whenever the chopper switch is off and using Kirchhoff Voltage Law in determining inductor voltage with respect to average current within the turn-on time, where is the time were a load voltage is zero. Equating both average current and taking the duty cycle , where is the average output voltage. Step-down chopper Taking a general step-down chopper with voltage source which is in series with the chopper switch, inductor, and the load with voltage . The diode would be in parallel with the series inductor and load. The same way by equating the average inductor current during the turn-on and turn-off time, we can get the average voltage by where is the average output voltage, is the duty cycle and is the source voltage. Step-up / step-down chopper Taking a general buck-boost chopper which works as stepup and down chopper, let the voltage source be in series with the chopper switch, reverse biased diode, and the load with voltage . The inductor would be in parallel with the series diode and load. The same way by equating the average inductor current during the turn-on and turn-off time, we can get the average voltage by where is the average output voltage, is the duty cycle and is the source voltage. See also Braking chopper Vibrator (electronic) References Literature C. Enz, G. Temes, - Proceedings of the IEEE, vol. 84 No. 11, Nov. 1996 A. Bilotti, G. Monreal, Chopper-Stabilized Amplifiers with a