Analog Devices,inc.

Scott A Wurcer

A Paul Brokaw

Lawrence M DeVito

Alex Gusinov

Douglas W Babcock

Robert A Duris

John Pierdomenico

Lewis W Counts

Brian Harrington

Robert F Day

Apparatus and methods for electronic amplification are provided. In one embodiment, an amplifier includes first and second input terminals, an amplification circuit, a feedback circuit, and a current mirror. The amplification circuit includes a non-inverting voltage input electrically connected to the first input terminal and to a bias voltage, an inverting voltage input electrically connected to the second input terminal, a voltage output, and a current output. The amplifier includes a first feedback path from the voltage output to the inverting voltage input through the feedback circuit and a second feedback path from the current output to the inverting voltage input through the current mirror, which can mirror a current from the current output to generate a mirrored current. A current source such as a transducer can provide an input current between the first and second input terminals, and the mirrored current can substantially match the input current.

Apparatus and methods for electronic amplification

In an embodiment of the invention, a differential input signal is coupled to a plurality of transconductance blocks. In some embodiments, each of the transconductance blocks divide an input transconductance among a plurality of signal paths to a plurality of outputs in each transconductance block. In an embodiment, the input transconductance may be divided based a ratio of transistor areas in the plurality of signal paths, though other embodiments may divide the transconductance differently. In some embodiments, transconductance block outputs of a plurality of transconductance blocks may be cross-coupled to provide a gain path for a differential signal than is greater than that of a common mode signal.

Enhancing dual op-amps for differential connections

An amplifier system with on-demand power supply boost includes an amplifier circuit for receiving an input signal and a charge pump connected to positive and negative power supplies and having predetermined supply voltages and being responsive to the input signal for increasing beyond the predetermined supply voltages the supply voltage applied to the amplifier in response to an increase in the input signal and a tracking charge pump usable in the amplifier system which includes a charge storage device; a unidirectional isolation device interconnecting the charge storage device and one pole of a power supply; a driver circuit responsive to an input signal and interconnected between both poles of the power supply; the power supply having predetermined power supply voltages; and a bias circuit for biasing the driver circuit to charge the charge storage device in the charge mode and in the boost mode, for increasing beyond the predetermined power supply voltages, the supply voltage supplied by the storage device to an external load in response to an increase in the input signal.

Amplifier system with on-demand power supply boost

A broadband modem hybrid transformer couples a broadband modem to a plain-old-telephone (POTs) line. The hybrid includes a full bridge having an impedance matching network to reduce the transhybrid attenuation of the hybrid. The second matching network(s) include various resistive and reactive components which together provide an impedance value selected based upon the impedance of the telephone line typically reflected into the primary windings of the transformer. The matching network increases the transhybrid attenuation of the hybrid, and thus reducing the amount of noise which couples from the modem transmit circuit to the modem receive circuit through the hybrid.

Broadband modem transformer hybird

A circuit for varying the temperature of a first bipolar transistor in order to thermally compensate for self-heating effects of an associated device in a common signal path with the first transistor, the first transistor being configured within an isolated collector region. The circuit includes a second bipolar transistor provided within the isolated collector region and thermally coupled to the first transistor, the second transistor operable for providing heat to the first transistor to alter the temperature to a predetermined level, thus changing the operational voltage characteristics of the first transistor so as to minimize shifts in offset voltage.

Circuit and method of providing thermal compensation for a transistor to

A distortion cancellation amplifier system operational amplifier system includes a current mirror circuit having an input, an output and a common terminal; a device for providing a pair of differential current signals to the input and output terminals of the current mirror circuit; a control device, responsive to said output terminal of the current mirror circuit, for controlling the voltage at the common terminal to drive the voltage at the input terminal of said current mirror circuit to track the voltage on the output terminal of the current mirror circuit; an output amplifier stage having a predetermined gain and having an input and an output terminal with its input terminal connected to the output terminal of the current mirror circuit; a gain control device having a predetermined impedance connected with the input terminal of the output amplifier; and a distortion suppression device connected between the output terminal of the output amplifier and the input terminal of the current mirror circuit and having an impedance equal to the predetermined impedance of the gain control device divided by the predetermined gain of the output amplifier for cancelling signal distortion introduced by the output amplifier stage.

Distortion cancellation amplifier system

In an FET differential input, preferably using a quad set of devices according to the teaching of U.S. Pat. No. 3,729,660, the channel of each transistor is formed in a piecewise manner, of multiple segments. Each channel segment is associated with a corresponding drain segment (i.e., these are multi-drain devices). Each drain segment is connected in series with a thin-film resistor. The channel area associated with each drain segment can be selectively removed from the circuit by cutting the connected resistor with a laser. The device's channel area (and its effective width to length ratio, Z/L) is thereby alterable. The thin film resistors are cut as the offset is measured, until an acceptably low (effectively zero) offset is obtained. This trimming operation can be performed at room temperature, and yields not only a near zero offset voltage, but also near zero drift. CMRR, further, will be maximized. Neither operating current ratio nor drain voltage need be, or is, changed.

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Cambridge, MA, United States of America

Scott A Wurcer