A semiconductor integrated circuit has a reception circuit configured to receive a strobe signal of which a logic is intermittently switched in synchronization with a data signal, an output circuit configured to extract a low frequency component including at least a DC component of the strobe signal received by the reception circuit and to output a first signal, and a comparison circuit configured to compare a signal level of the first signal with a threshold level. The reception circuit is configured to change a boost amount of a high frequency component different from the low frequency component of the strobe signal based on a comparison result obtained by the comparison circuit.

Certain aspects of the present disclosure generally relate to using cross-coupled transistors for source degeneration of an amplification stage. For example, the amplification stage generally includes a differential amplifier comprising transistors, cross-coupled transistors coupled to the differential amplifier, and an impedance coupled between drains of the cross-coupled transistors. In certain aspects, the differential amplifier comprises a push-pull amplifier, and the transistors of the push-pull amplifier comprise cascode-connected transistors.

A differential signal input buffer is disclosed. The differential signal input buffer may receive a differential signal that includes a first signal and a second signal and may be divided into a first section and a second section and. The first section may buffer and/or amplify the first signal based on a first level-shifted second signal. The second section may buffer and/or amplify the second signal based on a first level-shifted first signal. In some implementations, the first section may buffer and/or amplify the first signal based on a second level-shifted second signal. Further, in some implementations, the second section may buffer and/or amplify the second signal based on a second level-shifted first signal.

Linearity is improved in an amplifier circuit without lowering gain. The amplifier circuit includes a transistor, a load, an impedance element, and a variable current source. The transistor amplifies an input signal. The load is connected between the transistor and a power supply. The impedance element is connected between the transistor and a ground terminal, and passes a direct current. The variable current source is connected to a connection part between the transistor and the impedance element, and supplies a current in accordance with a voltage of the connection part.

A data storage device is disclosed comprising a head actuated over a magnetic media, wherein the head comprises a read element configured to generate a read signal when reading data from the magnetic media. A common-source common-gate (CS-CG) differential amplifier is coupled to the read element through a transmission line having a transmission line impedance Z.sub.0. A feedback circuit is coupled between an output of the CS-CG differential amplifier and an input of the CS-CG differential amplifier, wherein the feedback circuit is configured so that an input impedance of the CS-CG differential amplifier substantially matches the transmission line impedance Z.sub.0.

A data storage device is disclosed comprising a head actuated over a magnetic media, wherein the head comprises a read element configured to generate a read signal when reading data from the magnetic media. A common-source common-gate (CS-CG) differential amplifier is coupled to the read element through a transmission line having a transmission line impedance Z.sub.0. A feedback circuit is coupled between an output of the CS-CG differential amplifier and an input of the CS-CG differential amplifier, wherein the feedback circuit is configured so that an input impedance of the CS-CG differential amplifier substantially matches the transmission line impedance Z.sub.0.

A differential signal input buffer is disclosed. The differential signal input buffer may receive a differential signal that includes a first signal and a second signal and may be divided into a first section and a second section and. The first section may buffer and/or amplify the first signal based on a first level-shifted second signal. The second section may buffer and/or amplify the second signal based on a first level-shifted first signal. In some implementations, the first section may buffer and/or amplify the first signal based on a second level-shifted second signal. Further, in some implementations, the second section may buffer and/or amplify the second signal based on a second level-shifted first signal.

Linearity is improved in an amplifier circuit without lowering gain.

The amplifier circuit includes a transistor, a load, an impedance element, and a variable current source. The transistor amplifies an input signal. The load is connected between the transistor and a power supply. The impedance element is connected between the transistor and a ground terminal, and passes a direct current. The variable current source is connected to a connection part between the transistor and the impedance element, and supplies a current in accordance with a voltage of the connection part.

Techniques for monitoring a distortion signal of a power amplifier circuit, where the output of a distortion monitoring circuit includes little or no fundamental signal and closely represents the actual distortion of the amplifier circuit of a wired communications system. The power amplifier circuit can generate a distortion feedback signal that does not affect the power amplifier's output power capability, e.g., no inherent loss in the fundamental output of the amplifier. That is, using a distortion monitor circuit, the power amplifier circuit can resolve a distortion feedback signal from the intended output signal of the output power amplifier circuit.

In certain aspects, an amplifier includes a first transistor including a gate, a drain, and a source, wherein the gate of the first transistor is coupled to a first input of the amplifier. The amplifier also includes a second transistor including a gate, a drain, and a source, wherein the gate of the second transistor is coupled to a second input of the amplifier. The amplifier further includes a first signal path coupled between the first input of the amplifier and the source of the second transistor, a second signal path coupled between the second input of the amplifier and the source of the first transistor, a first load coupled to the drain of the first transistor, and a second load coupled to the drain of the second transistor.