Analog Devices,inc.

Analog Devices Global

Christian Steffen Birk

Colin Gerard Lyden

Patrick Joseph Pratt

Eoin Edward English

Michael C W Coln

John Anthony Cleary

Jeremy Richard Gorbold

Colin Charles Price

Mahesh Madhavan Kumbaranthodiyil

Tomas Tansley

Elizabeth A Lillis

Gerard Mora Puchalt

Jan Crols

Padraig O'Connor

Kathleen Embrechts

Wim Rens

David Sayago Montilla

An analog multiplexer may be used for sampling an input voltage that is capable of having a higher voltage level than an upper supply voltage. The analog multiplexer includes a plurality of input switch circuits and a shorting switch circuit. The plurality of input switch circuits include n-type or p-type laterally diffused field effect transistors (NLDFETs or PLDFETs). At least one of the input switch circuits includes a level shifting switch circuit that is able to sample an input voltage that is greater than the upper supply voltage for the multiplexer. A shorting switch circuit, at an output of the multiplexer, includes a capacitively coupled gate drive circuit and is configured to short a first differential output to a second differential output after the input voltage is sampled.

Analog multiplexer

Embodiments of the present invention may provide a method of measuring an unknown capacitance of a device. The method may comprise the steps of driving a test signal to a circuit system that includes a current divider formed by the device with unknown capacitance and a reference capacitor; mirroring a current developed in the reference capacitor to a second circuit system that includes a measurement impedance; measuring a voltage within the second circuit system; and deriving a capacitance of the unknown capacitance based on the measured voltage with reference to a capacitance of the reference capacitor and the measurement impedance.

Capacitance measurement

A bootstrapped switch circuit includes a first switch transistor to receive an input signal and a second switch transistor to provide an output signal. The sources of the switch transistors may be coupled. A voltage source may be coupled to the sources of the switch transistors and at least one of the gates of the switch transistors. The voltage source may generate a control voltage to activate at least one of the switch transistors based on a bias current. A voltage source driver may be coupled to the voltage source to generate the bias current based on a bias voltage. The bias voltage may include a first voltage approximately corresponding to an overdrive voltage of at least one of the switch transistors and a second voltage approximately corresponding to a threshold voltage of the switch transistors.

Four-quadrant bootstrapped switch circuit

A bootstrapped switch circuit can include at least one transistor, to receive an input signal and allow the input signal to pass through as an output signal based on a control signal, and a voltage-controlled voltage source, to provide first and second voltages between a gate and a source of the at least one transistor in response to the control signal. The voltage-controlled voltage source can include a differential pair and a current source. A gate of one of the differential pair can receive the control signal and a gate of the other of the differential pair can receive a logical inverse of the control signal. The current source can provide a current to connected sources of the differential pair. The first voltage can turn on the at least one transistor and be produced in response to a first logic state of the control signal resulting in the current of the current source flowing entirely through a first one of the differential pair. The second voltage can turn off the at least one transistor and be produced in response to a second logic state of the control signal resulting in the current of the current source flowing entirely through a second one of the differential pair.

Bootstrapped switch circuit

A bootstrapped switch circuit can include a switch transistor, having a drain configured as an input terminal to receive an input signal, and a voltage-controlled voltage source, configured to provide predetermined constant voltages between a gate and a source of the switch transistor in response to a control signal received at a control terminal. The predetermined constant voltages can include a first predetermined constant voltage to turn on the switch transistor and pass the input signal to the source and a second predetermined constant voltage to turn off the switch transistor. The first and second predetermined constant voltages can be independent of the magnitude of a signal passed to the source of the switch transistor based on the input signal at the drain.

A low power, low noise amplifier system includes at least one amplifier having first and second differential input terminals, first and second differential output terminals and providing a differential output; first and second input capacitors interconnected with the first and second differential amplifier input terminals; first and second feedback circuits containing first and second feedback capacitors, respectively, interconnected with the amplifier differential input and output terminals; an input chopper switch circuit for receiving a low frequency differential input and selectively, alternately swapping those low frequency differential inputs through the input capacitors to the differential input terminals of the amplifier; an output chopper switch for receiving and selectively, alternately swapping the amplifier differential outputs synchronously with the input chopper switch circuit; and a low pass filter responsive to the swapped differential outputs for providing a low noise, low power amplification of the low frequency differential inputs.

Low power, low noise amplifier system

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Innishannon, Ireland

Christian Steffen Birk