Stmicroelectronics S.r.l.

Consorzio Per La Ricerca Sulla Microelettronica Nel Mezzogiorno

Giovanni Galli

Giuseppe Scilla

A final stage for a high-speed comparator, and a method of driving an electric load having a capacitive component are disclosed. The final stage comprises a first or pull-up component and a second or pull-down component which are connected in series with each other between a first or supply voltage reference and a second voltage reference. A dynamic drive device and a separate static drive device are coupled to each component of the output stage. Each component of the final stage is driven separately according to whether it is in a static or a dynamic load condition.

Output stage for high-speed comparator circuits

The invention relates to a ground-compatible inhibit circuit structure and method, for circuits integrated in a semiconductor substrate which is unrelated to ground potential. The circuit structure is integrated in the same substrate as an associated circuit to be inhibited, and the substrate is covered with an epitaxial layer accommodating the components of the inhibit circuit structure. It includes a stable internal voltage reference and a circuit portion for comparing this reference with an inhibit signal in order to block the associated circuit upon a predetermined threshold value being exceeded, even in a condition of the signal potential being higher than the supply potential to the circuit. Advantageously, the epitaxial layer of each well is always at a potential higher than or equal to that of the substrate.

Ground compatible inhibit circuit

An active precision termination of the type incorporated in a voltage regulator for feeding the lines of an external bus is presented. Each termination includes a matching impedance connected in series to a switch formed by a MOS transistor, including a cell formed by a plurality of circuit branches provided in parallel and coupled to a unique output terminal. Each branch includes an input coupled to the series of the impedance and of the switch and receiving a control voltage signal. The body terminal of each MOS transistor receives a corresponding control signal via an inverter, whereas the control terminal of each MOS transistor receives a corresponding control voltage signal.

Accurate active termination device

A protection circuit is disclosed for a bipolar power transistor for preventing the operating point thereof from leaving a useful operating area. The protection circuit includes a sense resistor connected between an input supply voltage and a collector of the bipolar power transistor; a first branch circuit, including a first diode connected to the collector of the bipolar power transistor and a first current source connected between a common output node and the first diode; a second branch circuit, including a second diode and a second current source connected between the second diode and the common output node; and a third branch circuit. A short-circuit current level of the bipolar power transistor at relatively low voltage levels of the input supply voltage is based upon current levels for the first current source and the second current source and a resistance value of the sense resistor connected to the bipolar power transistor. The protection circuit further includes a fourth circuit branch including a current mirror connected to the common output node and a third current source connected between the input supply voltage and the current mirror. A short-circuit current level of the bipolar power transistor at relatively high voltage levels of the input supply voltage is substantially equal to the current level of the third current source.

Protection circuit for power transistor

A method, and associated circuit, which can prevent the latch-down phenomenon in transistors which are protected from going out of their SOAs. By supplementing the first protection circuit (against moving out of the SOA) with a second protection circuit which can drive the control terminal of the transistor such that when, upon the voltage across the main conduction path of the transistor being increased, the value of the current flowing through said path would tend, due to the first protection, to drop below a predetermined lower limit, that value can be kept approximately constant and unaffected by the load as seen from the output terminal of the transistor; the transistor will at all events supply the load with some current up to the acceptable limit VMAX by the transistor.

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Galati Marina, Italy

Giovanni Galli