An apparatus includes an input amplifier stage and a switch that has a first terminal at a virtual ground input of the input amplifier stage.

A current voltage conversion circuit includes first to fourth signal amplifiers; and first and second resistive passive elements, an input terminal of the first signal amplifier being connected to a terminal for inputting a current signal, one and the other terminals of the first resistive passive element being connected to output and input terminals of the first signal amplifier, respectively, an input terminal of the second signal amplifier being connected to a first connection point, input and output terminals of the third signal amplifier being connected to an output terminal of the second signal amplifier and the first connection point, respectively, an input terminal of the fourth signal amplifier being connected to a second connection point, and one and the other terminals of the second resistive passive element being connected to an output terminal of the fourth signal amplifier and the second connection point.

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.

An apparatus includes an input amplifier stage and a switch that has a first terminal at a virtual ground input of the input amplifier stage.

Apparatus and method for an output stage of an amplifier are disclosed. A current source circuit provides current to a transistor connected to the amplifier output node to produce output voltage, and the current source circuit has two current mirror paths, one of which replicates the output voltage at the output node. As the output voltage approaches rail, more current is steered to the current mirror path not replicating the output voltage and provides additional current or voltage necessary to keep the current source circuit operational.

In at least one embodiment, a method for operating a receiver includes configuring a receiver front-end circuit of the receiver according to a selected power consumption configuration. The method includes adjusting a quiescent current of a programmable flat gain stage coupled to the receiver front-end circuit according to the selected power consumption configuration to compensate for any gain loss of the receiver front-end circuit in the selected power consumption configuration. The selected power consumption configuration may be a reduced power consumption configuration and the programmable flat gain stage may be configured to at least partially compensate for the gain loss of the receiver front-end circuit in the reduced power consumption configuration.

In at least one embodiment, a method for operating a receiver includes configuring a receiver front-end circuit of the receiver according to a selected power consumption configuration. The method includes adjusting a quiescent current of a programmable flat gain stage coupled to the receiver front-end circuit according to the selected power consumption configuration to compensate for any gain loss of the receiver front-end circuit in the selected power consumption configuration. The selected power consumption configuration may be a reduced power consumption configuration and the programmable flat gain stage may be configured to at least partially compensate for the gain loss of the receiver front-end circuit in the reduced power consumption configuration.