Linear Technology Corporation

Other

Hengsheng Liu

Edson Wayne Porter

Gregory Jon Manlove

Arnold Erling Nordeng

A single stage current sense amplifier is described that generates a differential output that is proportional to a current through a sense resistor. The voltage across the sense resistor is Vsense. The current sense amplifier includes a differential transconductance amplifier having high impedance input terminals. An on-chip RC filter filters transients in the Vsense signal. A feedback circuit for each leg of the amplifier causes a pair of input transistors to conduct a fixed constant current irrespective of Vsense, which stabilizes the transconductance. A gain control resistor (Re) is coupled across terminals of the pair of input transistors and has Vsense across it. The current through the gain control resistor is therefore Vsensex1/Re. A level shifting circuit coupled to each of the input transistors lowers a common mode voltage at an output of the amplifier. Chopper circuits at the input and output cancel any offset voltages.

High side current sense amplifier

An operational amplifier circuit includes an input differential circuit and a trim circuit for sensing the operational amplifier's input common mode voltage and generating an offset correction voltage in response thereto. The trim circuit reduces the amplifier's offset voltage dependence on input common mode voltage, and hence improves the common mode rejection ratio of the operational amplifier circuit.

Common mode rejection ratio trim circuit and methodology

A folded cascode amplifier having improved slew comprises an input differential transistor pair circuit, a cascode branch circuit coupled to the differential pair circuit, and a boost circuit for increasing branch current when the amplifier is in a slew condition. The additional current increases slew of the amplifier without negatively affecting amplifier characteristics.

Folded cascode amplifier having improved slew performance

Voltage offset of an integrated circuit amplifier is accurately determined for calibration of the device. Circuit connections are established between the integrated circuit and an external device, such as an IC handler. Internal noise gain resistors formed within the integrated circuit are connected by internal switches to the amplifier and the output voltage is measured so that a value of a voltage offset of the amplifier while the noise gain resistors are connected can be calculated. The use of internal noise gain resistors produces a voltage offset component of the output voltage that is significantly greater in magnitude than effects of thermocouple voltages generated by circuit junction connections.

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Colorado Springs, CO, United States of America

Hengsheng Liu