Gerhard Nebel

Large bandwidth BiCMOS operational amplifiers for SC-video-applications

Two single-ended and one fully differential high-frequency BiCMOS operational amplifiers for switched-capacitor video-applications are presented. The amplifiers feature a folded cascode structure with current sources as output loads. For the single-ended amplifiers the current mirroring is accomplished with bipolar transistors at the output of the differential pair. The common-mode feedback circuitry of the differential amplifier uses two nested differential input pairs. The amplifiers are integrated in an analog 1 /spl mu/m BiCMOS process,with an active die area of 0.72 mm/sup 2/ and 0.96 mm/sup 2/ for the single-ended and the fully differential amplifier, respectively. For all amplifiers a dc-gain of 68 dB and a unity gain frequency greater than 200 MHz was obtained.<<ETX>>

A very low drop voltage regulator using an NMOS output transistor

A very low drop voltage regulator that uses an NMOS output transistor, a start-up circuit and two voltage comparators, designed in a 0.12 /spl mu/m CMOS technology, is presented. By means of a charge pump to control the gate of the NMOS transistor it is possible to obtain the very low voltage drop, between input and output, of only 100 mV. A novel sample and hold technique is used in order to slow down the charge pump and to save current in low power mode. The start-up circuit comprises a simple PMOS regulator and works without the accurate reference voltage of a bandgap, which is not stable during the first few microseconds. The regulator works in a wide load area from 20 /spl mu/A - its own current consumption - up to 50 mA, does not require any additional capacitors at its outputs and provides a low power mode.