A power amplifier includes a two-dimensional matrix of NM active cells formed by stacking main terminals of multiple active cells in series. The stacks are coupled in parallel to form the two-dimensional matrix. The power amplifier includes a driver structure to coordinate the driving of the active cells so that the effective output power of the two-dimensional matrix is approximately NM the output power of each of the active cells.

The present invention is directed to electrical circuits and techniques thereof. More specifically, an embodiment of the present invention provides a variable gain amplifier that includes a first transistor and a second transistor whose gate terminals are coupled to a first input terminal. A first drain terminal of the first transistor and a first source terminal of the second transistor is coupled to a voltage gain control switch. There are other embodiments as well.

An apparatus includes a first field effect transistor (FET) that has a body and is coupled in a circuit. The apparatus also includes a second FET that has a body and is coupled in the circuit. The circuit has an offset because of a mismatch. The apparatus further includes an offset correction circuit coupled to the body of the first FET and to the body of the second FET. The offset correction circuit provides a first offset correction signal to the body of the first FET and provides a second offset correction signal to the body of the second FET.

An apparatus includes a first field effect transistor (FET) that has a body and is coupled in a circuit. The apparatus also includes a second FET that has a body and is coupled in the circuit. The circuit has an offset because of a mismatch. The apparatus further includes an offset correction circuit coupled to the body of the first FET and to the body of the second FET. The offset correction circuit provides a first offset correction signal to the body of the first FET and provides a second offset correction signal to the body of the second FET.

A parallel resonant circuit with excellent distortion and saturation characteristics is provided at low power consumption. A first power-supply voltage is applied to the parallel resonant circuit. In the parallel resonant circuit, a variable resistor includes one or more parallel-connected branches. Each of the branches includes a series circuit of a resistor and a MOS switch. A second power supply supplies power of control signals applied to respective gates of the MOS switches, and supplies back gate voltages to the MOS switches. A power-supply voltage of the second power supply is higher than the first power-supply voltage.

In an embodiment, an amplifier circuit includes a second stage that includes a first switch circuit including first and second terminals, a plurality of resistive elements coupled between the first and second terminals of the first switch circuit, and a plurality of switches configured to control an equivalent resistance between the first and second terminals of the first switch circuit. During play mode, the second stage has a gain between the input of the second stage and the output of the second stage of a first value. During a transition from mute mode to play mode, the amplifier circuit is configured to progressively increase the gain of the second stage from a second value to the first value. During a transition from play mode to mute mode, the amplifier circuit is configured to progressively decrease the gain of the second stage from the first value to the second value.