Analysis and Design of Analog Integrated Circuits
- P. R. Gray, P. Hurst, S. Lewis
- 4th ed., Wiley
An input stage using Darlington configuration with a lateral PNP and a vertical PNP combination for operational amplifier (Op-Amp) is presented in this paper. The emitter degeneration resistors are added to enhance the slew rate of the amplifier. To decrease the input offset voltage, the base current traced compensation technique is used to balance and compensate the different current component between the two input current branches through the current mirrors. This input stage is fabricated with the standard bipolar process, and the typical input offset voltage of 1mV, temperature coefficient of input offset voltage is around 5μV/°C over -55°C to 125°C, slew rate of 9.2V/μs and low input bias current are achieved without any trimming techniques.