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.

Disclosed is an operational amplifier based on a metal-oxide TFT. The operational amplifier includes an auxiliary amplifier and a bootstrap gain-increasing amplifier. The auxiliary amplifier adopts a two-stage positive feedback structure, including a fifth transistor, a seventh transistor, an eleventh transistor, a first amplifying unit, and a second amplifying unit. A gate of the fifth transistor serves as an input end of the operational amplifier. The bootstrap gain-increasing amplifier includes two second circuits in mutual symmetry. Each of the second circuits includes a first transistor, a second transistor, and a current source unit with a bootstrap structure.

An amplifier includes a first input circuit, a second input circuit, a first compensation circuit, a second compensation circuit. The first input circuit changes a voltage level of the negative output node based on a first input signal. The second input circuit changes a voltage level of the positive output node based on a second input signal. The first compensation circuit changes the voltage level of the positive output node based on the first input signal. The second compensation circuit changes the voltage level of the negative output node based on the second output signal.

Disclosed is an operational amplifier based on a metal-oxide TFT. The operational amplifier includes an auxiliary amplifier and a bootstrap gain-increasing amplifier. The auxiliary amplifier adopts a two-stage positive feedback structure, including a fifth transistor, a seventh transistor, an eleventh transistor, a first amplifying unit, and a second amplifying unit. A gate of the fifth transistor serves as an input end of the operational amplifier. The bootstrap gain-increasing amplifier includes two second circuits in mutual symmetry. Each of the second circuits includes a first transistor, a second transistor, and a current source unit with a bootstrap structure.

An equalizer having a split folded cascode architecture includes a circuit having a differential pair with a single tail current source and split folded cascode branches. The single tail current source eliminates the input referred offset due to a mismatch in current sources. The folded cascode amplifier acts as the equalizer, which is split into a derivative path and a proportional path. The derivative path boosts the high frequency components of the received signal. The gain of the low frequency components of the received signal is adjusted by the proportional path. The derivative path includes variable capacitors and variable resistors which allow fixing a ‘zero’ frequency and peak gain frequency to a predetermined value, wherein frequencies greater than the ‘zero’ frequency are boosted. The proportional path includes variable resistors, which allow adjusting the low frequency gain without affecting the ‘zero’ frequency and peak gain frequency.

An equalizer having a split folded cascode architecture includes a circuit having a differential pair with a single tail current source and split folded cascode branches. The single tail current source eliminates the input referred offset due to a mismatch in current sources. The folded cascode amplifier acts as the equalizer, which is split into a derivative path and a proportional path. The derivative path boosts the high frequency components of the received signal. The gain of the low frequency components of the received signal is adjusted by the proportional path. The derivative path includes variable capacitors and variable resistors which allow fixing a ‘zero’ frequency and peak gain frequency to a predetermined value, wherein frequencies greater than the ‘zero’ frequency are boosted. The proportional path includes variable resistors, which allow adjusting the low frequency gain without affecting the ‘zero’ frequency and peak gain frequency.

An amplifier circuit comprises a differential input stage and a differential output stage. The differential input stage includes a first differential input transistor pair coupled to a differential input of the amplifier circuit, and a second differential input transistor pair coupled to the differential input and the differential output stage; a degeneration impedance coupled between first transistors of the first and second differential input transistor pairs and second transistors of the first and second differential input transistor pairs; and a feedback circuit coupled to the first and second differential input transistor pairs and the degeneration impedance, wherein output current is provided from the differential input stage to the differential output stage by the feedback circuit and transition current is provided to the output stage by the second differential input transistor pair.

An amplifier includes: a first input transistor connected to a first input, a first output, and a power source or a ground, a second input transistor connected to a second input, a second output, and the power source or the ground; a first replica transistor connected to the first input, a detection node, and the power source or the ground; a second replica transistor connected to the second input, the detection node, and the power source or the ground; and a bias transistor connected to a bias voltage, the detection node, and the power source or the ground.

An amplifier circuit comprises a differential input stage and a differential output stage. The differential input stage includes a first differential input transistor pair coupled to a differential input of the amplifier circuit, and a second differential input transistor pair coupled to the differential input and the differential output stage; a degeneration impedance coupled between first transistors of the first and second differential input transistor pairs and second transistors of the first and second differential input transistor pairs; and a feedback circuit coupled to the first and second differential input transistor pairs and the degeneration impedance, wherein output current is provided from the differential input stage to the differential output stage by the feedback circuit and transition current is provided to the output stage by the second differential input transistor pair.

An amplifier includes: a first input transistor connected to a first input, a first output, and a power source or a ground, a second input transistor connected to a second input, a second output, and the power source or the ground; a first replica transistor connected to the first input, a detection node, and the power source or the ground; a second replica transistor connected to the second input, the detection node, and the power source or the ground; and a bias transistor connected to a bias voltage, the detection node, and the power source or the ground.