Sgs-thomson Microelectronics Limited

S Gs - Microelectronics Limited

Solomon K Ng

Karl M Schlager

Gee H Loh

Francesco Carobolante

The invention relates to a level shifter coupled to a circuit of a predetermined value, includes a differential amplifier with a first input coupled to the reference voltage and a second input receiving an intermediate voltage; a low impedance source providing the reference voltage; and a first operational amplifier providing the intermediate voltage from an input voltage. The output of the low impedance source is directly connected to the first input of the differential amplifier and the gain of the first operational amplifier is set to obtain a desired ratio between the reference voltage and the intermediate voltage.

Level shifter

An automatic gain control circuit comprising a variable gain amplifier having first and second differential gain control terminals, the first gain control terminal being connected to a constant reference voltage, a peak detector connected to the output of the variable gain amplifier and an integrator connected between the output of the peak detector and the second differential gain control terminal. The circuit further includes an integrating capacitor coupled to a ground terminal and a second capacitor connected between the first and second differential gain control terminals.

Automatic gain control circuit using a capacitor for minimizing digital coupling

A source/sink current generating circuit is arranged to generate source and sink currents which are matched and insensitive to fan out. This is achieved by using a biasing transistor (Q13) between first and second current mirrors which generate respectively the source and sink currents.

Source/sink current generating circuit system

A circuit for providing a reference current comprises first and second matched transistors, each of which has a control node and a controllable path and each of which is connected so that a current setting resistor is in the controllable path of the second matched transistor, the current setting resistor having a value, current set in the controllable path of the second matched transistor is related to a difference in voltage characteristics between the first and second matched transistors and to the value of the current setting resistor, and third and fourth matched transistors, each of the third and fourth matched transistors having a controllable path connected respectively to the controllable paths of the first and second matched transistors, and control electrodes of the third and fourth matched transistors connected together; a set of output transistors connected to the circuit to supply the reference current in dependence on a set current; and a fifth transistor having a controllable path between a bias node related to a first supply voltage level and a node set at one voltage characteristic relative to a second supply voltage level so as to maintain a voltage across one of the third and fourth matched transistors at a value which is independent of the first supply voltage level to reduce a magnitude of changes in the reference current as a function of the first supply voltage, the fifth transistor having a control electrode connected to the conductive path of the first matched transistor.

Reference current source for low supply voltage operation

Circuitry for selectably connecting the body node of drive transistors of a motor control circuit. In particular, those transistors that are turned off when operating the motor in a unipolar mode have their body nodes switched so as to be connected to a reference voltage, such as ground, during unipolar mode, and to be connected to the transistor source during bipolar mode (i.e., when the transistors are active). The circuitry also is operable to briefly connect the body nodes of the transistors to their source when the opposing drive transistor is commutated, in the unipolar mode. In this way, forward biasing of inherent diodes in the drive transistor is avoided in unipolar mode, except when useful to clamp the inductive kick of the motor coils.

Circuitry for switching the body nodes of driver transistors in drive

A chopper stabilized current amplifier circuit is disclosed. The current amplifier circuit includes a main operational transconductance amplifier, a nulling transconductance amplifier, two capacitors, four switches, and a timing control circuit. The timing control circuit uses analog inverters to decrease the slew rate of the switching of the switches to decrease the noise in the system.

Growing community of inventors

Singapore, Singapore

Solomon K Ng