Measurement of signal power for variable or time varying signals. A log-linear VGA coupled in a feedback configuration to a difference detector and an integrator, includes a set of amplifier cells selectable by a sliding current generator, producing a sum of outputs. Outputs of the sliding current generator include a first control current provided using a sum of amplified currents, a sequence of intermediate control currents, and a final control current provided using a sum of amplified currents. Control currents to be summed can be differentially amplified or attenuated; attenuators include capacitors to compensate for capacitive loading. Selectable amplifier cells are differentially amplified or attenuated. Isolating switches and canceling stages reduce the effects of leakage between adjacent amplifier cells. The sliding current generator can have boosted current to first and last amplifier cells, providing a more linear-in-dB gain near a relative maximum or minimum.

A chopper circuit (100) for a multipath chopper amplifier (201) is described. The chopper circuit (100) comprises a first chopper device (110) in a first circuit path (111), wherein the first chopper device (110) is configured to be controlled by a first clock signal (315), which has a first frequency; and a second chopper device (120) in a second circuit path (121), parallel to the first circuit path (111), wherein the second chopper device (120) is configured to be controlled by a second clock signal (325), which has a second frequency, wherein the first frequency is greater than the second frequency. Furthermore, a corresponding method of chopping an input signal (102) is described.

Disclosed examples include differential amplifier circuits and variable neutralization circuits for providing an adjustable neutralization impedance between an amplifier input node and an amplifier output node, including neutralization impedance T circuits with first and second impedance elements in series between the amplifier input and output, and a third impedance element, including a first terminal connected to a node between the first and second impedance elements, and a second terminal connected to a transistor. The transistor operates according to a control signal to control the neutralization impedance between the amplifier input node and the amplifier output node.

Disclosed examples include differential amplifier circuits and variable neutralization circuits for providing an adjustable neutralization impedance between an amplifier input node and an amplifier output node, including neutralization impedance T circuits with first and second impedance elements in series between the amplifier input and output, and a third impedance element, including a first terminal connected to a node between the first and second impedance elements, and a second terminal connected to a transistor. The transistor operates according to a control signal to control the neutralization impedance between the amplifier input node and the amplifier output node.

Disclosed examples include differential amplifier circuits and variable neutralization circuits for providing an adjustable neutralization impedance between an amplifier input node and an amplifier output node, including neutralization impedance T circuits with first and second impedance elements in series between the amplifier input and output, and a third impedance element, including a first terminal connected to a node between the first and second impedance elements, and a second terminal connected to a transistor. The transistor operates according to a control signal to control the neutralization impedance between the amplifier input node and the amplifier output node.

Various embodiments of the present technology may comprise methods and apparatus for an amplifier circuit. Methods and apparatus for an amplifier circuit according to various aspects of the present invention may provide a first cross-connect circuit responsive to a first clock signal having a first phase and the third clock signal having a third phase. The amplifier circuit may provide a second cross-connect circuit responsive to a second clock signal having a second phase and a fourth clock signal having a fourth phase. The clock signals have a same frequency with offset phases.

Systems and methods for measurement of signal power, when the signal is substantially variable or otherwise time varying. A log-linear VGA is coupled in a feedback configuration to a difference-of-squares detector and an integrator. The log-linear VGA includes a set of selectable amplifier cells. A sliding current generator selects one or more amplifier cells, wholly or partially, producing a sum of outputs. Some of the selectable amplifier cells have differential amplification, while others have similar amplification but are differentially attenuated. Switches turn off to isolate amplifier cells when the cell is not selected. Canceling circuits produce an output opposite to unselected amplifier cells, providing a sum near zero. Temperature compensation and other adjustment include two components: when the output y and the input x have the relation y=a+b log x the log-linear VGA can adjust either the offset or slope.

Various embodiments of the present technology may comprise methods and apparatus for an amplifier circuit. Methods and apparatus for an amplifier circuit according to various aspects of the present invention may comprise a first cross-connect circuit configured to receive an input signal at an input terminal and transmit the input signal to an input stage circuit. The amplifier circuit may further comprise a second cross-connect circuit connected between the input stage circuit and an output stage circuit, and a voltage adjustment circuit connected to the input stage circuit. Each cross-connect circuit may comprise a plurality of switches.

An amplifier circuit with novel design is provided. The amplifier circuit includes an input stage, a resistor, an output stage, an intermediate stage and a gm circuit. The input stage is coupled to a first supply voltage, and is arranged to receive an input voltage and a feedback current. The resistor is coupled between the input voltage and the input stage. The output stage is coupled to a second supply voltage, and is arranged to provide an output voltage for driving a load. The intermediate stage is coupled between the input stage and the output stage, and includes a level shifter. The gm circuit is coupled to the input stage, and is arranged to compare the input voltage with a common mode voltage, and thereby generates a compensate current for the input stage.

An amplifier circuit with novel design is provided. The amplifier circuit includes an input stage, a resistor, an output stage, an intermediate stage and a gm circuit. The input stage is coupled to a first supply voltage, and is arranged to receive an input voltage and a feedback current. The resistor is coupled between the input voltage and the input stage. The output stage is coupled to a second supply voltage, and is arranged to provide an output voltage for driving a load. The intermediate stage is coupled between the input stage and the output stage, and includes a level shifter. The gm circuit is coupled to the input stage, and is arranged to compare the input voltage with a common mode voltage, and thereby generates a compensate current for the input stage.