Analog Devices,inc.

Alan K Jeffery

Sandro Herrera

A low capacitance n-channel analog switch circuit, a p-channel analog switch circuit, and a full CMOS transmission gate (T-gate) circuit are described. Resistive decoupling can be used to isolate the switch or T-gate from AC grounds. A semiconductor region that is separated from a body region of a pass field-effect transistor (FET), such as by an insulator, can be coupled to or driven to a voltage similar to the input voltage or other desired bias voltage (e.g., an operational amplifier output) to help reduce parasitic capacitance of the switch or T-gate. The switch or T-gate can help provide improved frequency bandwidth or frequency response. The switch can be useful in a programmable gain amplifier (PGA) or programmable gain instrumentation amplifier (PGIA) or other circuit in which excessive switch capacitance could degrade circuit performance.

Low capacitance switch for programmable gain amplifier or programable gain instrumentation amplifier

A low capacitance n-channel analog switch circuit, a p-channel analog switch circuit, and a full CMOS transmission gate (T-gate) circuit are described. Resistive decoupling can be used to isolate the switch or T-gate from AC grounds, such as one or more switch control signal inputs or supply voltages. A semiconductor region that is separated from a body region of a pass field-effect transistor (FET) can be coupled to or driven to a voltage similar to the input voltage or other desired voltage to help reduce parasitic capacitance of the switch or T-gate. The switch or T-gate can have improved frequency bandwidth or frequency response. The switch can be useful in a programmable gain amplifier (PGA) or programmable gain instrumentation amplifier (PGIA) or other circuit in which excessive switch capacitance could degrade circuit performance.

Low capacitance analog switch or transmission gate

A soft start amplifier provides a soft-start function that controls a battery charging current in a feedback loop charging circuit by selecting the lowest voltage between a soft start voltage and an error derived control voltage. The lowest voltage is used as a control signal for controlling the battery charging current in the feedback loop charging circuit. The error voltage is a difference between a voltage proportional to the charging current and a voltage proportional to the target charging current while the soft start voltage is a voltage configured to ramp up with time. Using the lower voltage of the error voltage and the soft start voltage reduces the inrush current that may occur when the error derived control voltage spikes to the supply voltage in an attempt to correct the initial difference between the target charging current and a measured charging current.

Growing community of inventors

North Andover, MA, United States of America

Alan K Jeffery