Analog Devices,inc.

Stefano I D'Aquino

Kimo Y F Tam

Jennifer W Pierdomenico

Anthony E Turvey

Michael E Harrell

Edward L Collins

Adrian P Brokaw

Kimo Tam

Sandro Herrera

David Hall Whitney

Yukihisa Handa

Andrew Y Wang

A clamp circuit comprises an output transistor and a replica transistor coupled as a current minor pair, wherein the replica transistor is scaled in size to the output transistor by a size ratio; a first current source configured to set a current in the replica transistor, wherein the output current is set at a clamped output current value that is a sum of current of the first current source and a scaled value of the current of the first current source determined according to the size ratio; and a register circuit, wherein a register value stored in the register circuit sets the clamped output current value.

Output voltage glitch reduction in test systems

An automated testing system comprises a high side switch circuit coupled to an input/output (I/O) connection, a low side switch circuit coupled to the I/O connection, a high side force amplifier (HFA) coupled to the high side switch, a low side force amplifier (LFA) coupled to the low side switch, an adjusting circuit coupled to the HFA and the LFA, and a control circuit configured to change the adjusting circuit to change control of current at the I/O connection from one of the HFA or LFA to the other of the HFA or LFA.

Output voltage glitch reduction in ate systems

Techniques are provided for changing a range of an output circuit with little or no voltage or current glitch. In an example, a method of changing a range of an output signal can include providing a first level of the output signal at an output of a first amplifier based on a received setpoint signal and receiving a range change command. In response to the range change command an input of a second amplifier can be shorted to an output of the second amplifier for a first interval. At the end of the first interval and over a second interval, a first impedance between the input of the second amplifier and the output of the second amplifier can be increased, and a second impedance between the input of the second amplifier and the setpoint signal can be increased.

Low-glitch range change techniques

A system and method for controlling current-range switching to limit glitching includes a sense array connected between an input and a load. The sense array includes a parallel first and second branch circuits. The first branch circuit includes at least one first transistor, a first sense resistor, and a variable impedance control circuit. The variable impedance control circuit is configured to receive a control signal and generate a gate voltage of the at least one first transistor to establish an impedance of the sense array between the input and the load that is proportional to the control signal, including controlling the gate voltage of the at least one first transistor such that an impedance of the sense array transitions from a first value to a second value when connecting or disconnecting the first branch circuit between the input and the load while the input is connected to the load through the second branch circuit.

Variable impedance switching control

Apparatus and methods for loss of signal detection are provided. In one embodiment, a detection circuit for monitoring an input includes a small signal boost circuit, a rectifier circuit, a low-pass filter, and one or more comparators. The small signal boost circuit can generate an amplified signal by providing a first amount of gain to an input signal when the input signal is relatively small, but can saturate and provide reduced gain without external gain control adjustment when the input signal does not have a relatively small magnitude. The rectifier circuit can rectify the boosted signal to generate a rectified signal, and the low-pass filter can filter the rectified signal to generate a filtered signal. The one or more comparators can compare the filtered signal to one or more decision threshold voltages to determine the presence or absence of the input signal on the input.

Apparatus and methods for loss of signal detection

Apparatus and methods for frequency compensation of an amplifier are provided. In one embodiment, an integrated circuit (IC) includes an amplifier configured to amplify an input signal to generate an output signal. The IC further includes an output pad configured to receive an output signal from the amplifier and a control pad for controlling the closed-loop bandwidth of the amplifier. A compensation capacitor is electrically connected between an input of the inverting amplification block and an output of the inverting amplification block, and a switchable capacitor is electrically connected between the input of the inverting amplification block and the control pad. The control pad can be electrically connected to a DC voltage source or to the output pad to control the amplifier's closed-loop bandwidth.

Apparatus and methods for frequency compensation of an amplifier

A transconductance cell includes a positive rail for providing a positive power supply voltage and a negative rail for providing a negative power supply voltage. A pair of voltage inputs, one inverting and one non-inverting, develop a differential voltage input signal having a common mode voltage range from one of the rail voltages to within a volt or less of the other rail voltage. And a pair of cross-coupled transconductor circuits each have: (i.) a source voltage follower responsive to one of the voltage inputs for sourcing relatively unbounded output current at unity voltage gain, (ii.) a sink voltage follower responsive to the other voltage input for sinking unbounded output current to a current output terminal, and (iii) a transconductance resistor connected between the source voltage follower and the sink voltage follower for developing a differential output current proportional to the differential voltage input signal. Transconductance of the cell is substantially constant over the range of the differential voltage input signal without limiting the differential output current.

Low headroom X-bridge transconductor

An amplifier structure includes shield conductors that are provided spatially adjacent to elongated feedback signal lines that couple a feedback circuit to an amplifier input. The shield conductors are provided between the feedback signal lines and a ground plane, which interrupts a parasitic capacitance that otherwise would be established between the feedback signal line and ground. The shield conductors are electrically coupled to the amplifier's outputs which create a capacitance between the output terminal and the feedback signal line. In some embodiments, the capacitance generated between the output terminal and the feedback signal line can suffice as a capacitor in a feedback path of the amplifier and be contained in an integrated circuit die on which the amplifier is manufactured. Optionally, a structure may be provided that eliminates common mode signals on the feedback lines while simultaneously preserving the common mode signals on the amplifier output terminals. In this option, a second amplifier is provided that, in response to common mode variations at the output terminal, generates counterbalancing voltage variations on a second circuit that is coupled to the feedback lines at their source. The two variations cancel each other out at nodes from which the feedback lines originate, which substantially reduces feedback common mode variation even when there is common mode variation at the output terminals.

Integrated circuit having on die structure providing capacitance in amplifier feedback path

A multi-fferential amplifier system includes an amplifier having a plurality of amplifier inputs and a plurality of amplifier outputs; a plurality of input terminals for receiving a plurality of inputs and being interconnected with the amplifier inputs through a plurality of input impedances, respectively, and a feedback network including a plurality of summing circuits for combining the plurality of amplifier outputs in a plurality of different sets of groups each group numbering one fewer than the plurality, respectively, and feeding back the sum of each group of amplifier outputs to the remaining amplifier input for maintaining the difference between any group of amplifier outputs proportional to the difference of a corresponding group of inputs at the terminals and maintaining the average value of the amplifier outputs constant and unrelated to the inputs at the terminal. Also disclosed is a multi-fferential amplifier including a plurality of differential input/output circuits responsive to a plurality of input signals and providing a plurality of output signals; each input signal is shared between a different set of differential input/output circuits in a plurality of different sets of groups, each group numbering one fewer than the plurality; each differential input/output circuit receives one input signal at its positive input and the other input signal at its negative input.

Trifferential amplifier and trifferential amplifier system

An output distortion correction amplifier system includes an input stage; a current mirror connected to the input stage; an output stage having its input connected to the input stage and a current mirror and its output connected to the input stage; a compensation impedance connected to the input of the output stage; and a distortion correction circuit for directly sensing the distortion voltage across the output stage and providing to the current mirror a current representative of the distortion voltage for delivering to the compensation impedance a correction current to develop a correction voltage at the input of the output stage to nullify the effect of the distortion voltage.

Output distortion correction amplifier system

An input distortion correction current-feedback amplifier system includes a current mirror; an input stage connected to the input of the current mirror; an output stage connected to the output of the current mirror; a feedback circuit connected from the output stage to the input stage; a compensation impedance connected to the output of the current mirror; and a distortion correction circuit for sensing the distortion voltage across the input stage and providing to the current mirror a current representative of the distortion voltage for delivering to the compensation impedance a correction current to develop a correction voltage at the input of the output stage to nullify the effect of the distortion voltage.

Input distortion correction current-feedback amplifier system

An Early voltage and beta current compensated cascode current mirror includes a cascode current mirror having an input stage responsive to an input current, a current mirror circuit having a first stage responsive to the input stage and a second stage responsive to the first stage, and an output stage responsive to the second stage for providing an output voltage and current; and a compensation circuit, responsive to the cascode current mirror, having a first compensation stage, a second compensation stage and a bootstrapping buffer, the first compensation stage, in response to a change in the output voltage, impressing a corresponding change in voltage on the second compensation stage, the second compensation stage thereby providing a change in current to the cascode current mirror for cancelling current errors induced by base current modulation in the output stage, the bootstrapping buffer, in response to the change in voltage, impressing a corresponding change in voltage on the first compensation stage to prevent errors from base current modulation effects in the first compensation stage, the first and second compensation stages further providing a base current to the cascode current mirror for cancelling base current errors in the output current induced by the cascode current mirror.

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Westford, MA, United States of America

Stefano I D'Aquino