A local oscillator buffer circuit comprises a complementary common-source stage comprising a first p-channel transistor (MCSP) and a first n-channel transistor (MCSN), arranged such that their respective gate terminals are connected together at a first input node, and their respective drain terminals of each of is connected together at a buffer output node. A complementary source-follower stage comprises a second p-channel transistor (MSFP) and a second n-channel transistor (MSFN), arranged such that their respective gate terminals are connected together at a second input node, and their respective source terminals are connected together at the buffer output node.

A local oscillator buffer circuit comprises a complementary common-source stage comprising a first p-channel transistor (MCSP) and a first n-channel transistor (MCSN), arranged such that their respective gate terminals are connected together at a first input node, and their respective drain terminals of each of is connected together at a buffer output node. A complementary source-follower stage comprises a second p-channel transistor (MSFP) and a second n-channel transistor (MSFN), arranged such that their respective gate terminals are connected together at a second input node, and their respective source terminals are connected together at the buffer output node.

In one form, a signal generator system such as a power amplifier system includes an amplification stage, a lowpass filter, and a controller. The amplification stage includes a first amplifier having an input for receiving an input signal, a control input for receiving a first control signal, and an output. The lowpass filter has a first input coupled to the output of the first amplifier, and an output. The controller has a first input coupled to the output of the lowpass filter, and a first output coupled to the control input of the first amplifier, wherein the controller varies the first control signal to reduce a difference between the output of the lowpass filter and a first target voltage level.

In one form, a signal generator system such as a power amplifier system includes an amplification stage, a lowpass filter, and a controller. The amplification stage includes a first amplifier having an input for receiving an input signal, a control input for receiving a first control signal, and an output. The lowpass filter has a first input coupled to the output of the first amplifier, and an output. The controller has a first input coupled to the output of the lowpass filter, and a first output coupled to the control input of the first amplifier, wherein the controller varies the first control signal to reduce a difference between the output of the lowpass filter and a first target voltage level.

In an output amplifier stage of an operational amplifier circuit, the first p-well of the first nMOSFET and the second p-well of the second nMOSFET are connected to the fourth node. Further, the first n-well of the first pMOSFET and the second n-well of the second pMOSFET are connected to the fifth node. At least one of the fourth node and the fifth node is connected to an output terminal VOUT.

In an output amplifier stage of an operational amplifier circuit, the first p-well of the first nMOSFET and the second p-well of the second nMOSFET are connected to the fourth node. Further, the first n-well of the first pMOSFET and the second n-well of the second pMOSFET are connected to the fifth node. At least one of the fourth node and the fifth node is connected to an output terminal VOUT.