Modesto is a low voltage step up converter design as a closed-loop bias control of GSM power amplifiers. Modesto facilitates accurate control of the current delivered to the power amplifier through an I2C interface. This unique topology is useful in time-division-multiple-access (TDMA) systems, such as GSM, where accurate transmit burst shaping and power control is required. Modesto operates from a single 2.3V to 5.5V supply and typically draws 0.3mA of supply current. The output range is from VCC to 8V with 25mV step resolution.