Circuitry for reducing distortion over a wide frequency range

A composite amplifier comprising:

• a main amplifier circuit, having a main component network and a main amplifier, wherein the main amplifier comprises:
• a first input channel on which a first input signal is input to a non-inverting input node of the main amplifier;
• an inverting input node;
• a first output channel from which a first output signal is output from the main amplifier on a corresponding first output node, the main amplifier introducing an error component, introduced by offsets or nonlinearities in the main amplifier circuit, into the first output signal;
• a compensation amplifier circuit, connected to the first input channel and the first output channel, having a compensation component network and a compensation amplifier, wherein the compensation amplifier comprises:
• a non-inverting input node, wherein the non-inverting input node is connected to the first output channel via the compensation component network;
• an inverting input node, wherein the inverting input node is connected to the first input channel;
• wherein the compensation amplifier circuit is arranged to sense the error of the first output channel of the main amplifier circuit, and generate a first error compensation signal in dependence thereon, the arrangement being such that the first error compensation signal is applied to the inverting input node of the main amplifier;
• and
• wherein the error compensation signal lowers the error in the output signal.

A composite amplifier comprising:

• a main amplifier circuit, having a main component network and a main amplifier, the amplifier having a first input channel on which a first input signal is input to a first input node of the main amplifier and a first output channel from which a first output signal is output from the main amplifier on a corresponding first output node, the main amplifier circuit responding to the first input signal to produce an output signal including an error component introduced by offsets or nonlinearities in the main amplifier circuit;
• a compensation amplifier circuit connected to the first input channel and first output channel of the main amplifier circuit to receive the first input signal and the first output signal, and having a compensation component network and a compensation amplifier, the arrangement being such that the compensation amplifier circuit combines the first input signal and the first output signal to cancel the first input and first output signals, leaving the error in the first output signal introduced by the main amplifier circuit as an input to the compensation amplifier, the compensation amplifier circuit thereby being arranged to sense the error on the first output channel of the main amplifier circuit, and generate a first error compensation signal in dependence thereon, such that the first error compensation signal is then applied to the main amplifier circuit, wherein the error compensation signal lowers the error in the output signal;
• a second main amplifier circuit, having a second main component network and a second main amplifier, the second main amplifier having a second input channel on which a second input signal is input to a first input node of the second main amplifier and a second output channel from which a second output signal is output from the second main amplifier on a corresponding first output node of the second main amplifier, the second main amplifier circuit responding to the second input signal to produce a second output signal including an error component introduced by offsets or nonlinearities in the second main amplifier circuit;
• a second compensation amplifier circuit connected to the second input channel and second output channel of the second main amplifier circuit to receive the second input signal and the second output signal, and having a second compensation component network and a second compensation amplifier, the arrangement being such that the second compensation amplifier circuit combines the second input signal and the second output signal to cancel the second input and second output signals, leaving the error in the second output signal introduced by the second main amplifier circuit as a first input to a first input node of the second compensation amplifier, the second compensation amplifier circuit thereby being further arranged to sense the error on the second output channel of the second main amplifier circuit, and generate a second error compensation signal in dependence thereon, the arrangement being such that the second error compensation signal is then applied to the second main amplifier circuit, wherein the second error compensation signal lowers the error in the second output signal;
• and
• connections arranged so as to cause the composite amplifier to operate as an oscillator, the connections comprising the first output channel of the main amplifier circuit being coupled to the second input channel of the second main amplifier circuit, wherein the first output signal is the second input signal, and the second output channel of the second main amplifier circuit being coupled to the first input channel of the main amplifier circuit, wherein the second output signal is the first input signal.

A composite amplifier comprising:

• a main amplifier circuit, having a main component network and a main amplifier, the amplifier having a first input channel on which a first input signal is input to a first input node of the main amplifier and a first output channel from which a first output signal is output from the main amplifier on a corresponding first output node, the main amplifier circuit responding to the first input signal to produce an output signal including an error component introduced by offsets or nonlinearities in the main amplifier circuit;
• a compensation amplifier circuit connected to the first input channel and first output channel of the main amplifier circuit to receive the first input signal and the first output signal, and having a compensation component network and a compensation amplifier, the arrangement being such that the compensation amplifier circuit combines the first input signal and the first output signal to cancel the first input and first output signals, leaving the error in the first output signal introduced by the main amplifier circuit as an input to the compensation amplifier, the compensation amplifier circuit thereby being arranged to sense the error on the first output channel of the main amplifier circuit, and generate a first error compensation signal in dependence thereon, such that the first error compensation signal is then applied to the main amplifier circuit, wherein the error compensation signal lowers the error in the output signal;
• wherein the composite amplifier is a differential amplifier, further having a second input channel on which a second input signal is input to a second input node of the main amplifier and a second output channel from which a second output signal is output from the main amplifier on a corresponding second output node, the main amplifier circuit responding to the second input signal to produce a second output signal including an error component introduced by offsets or nonlinearities in the main amplifier circuit;
• and
• the compensation amplifier circuit being further connected to the second input channel and the second output channel of the main amplifier circuit to receive the second input signal and the second output signal, and having a compensation component network and a compensation amplifier, the arrangement being such that the compensation amplifier circuit combines the second input signal and the second output signal to cancel the second input and second output signals, leaving the error in the second output signal introduced by the main amplifier circuit as an input to a second input of the compensation amplifier, the compensation amplifier circuit thereby being arranged to sense the error on the second output channel of the main amplifier circuit in addition to the first output channel, and generate a second error compensation signal in dependence on the error on the second output channel, the arrangement being such that the second error compensation signal is then applied to the second input channel of the main amplifier circuit and the first error compensation signal is then injected back onto the first input channel of the main amplifier circuit, wherein the error compensation signals lower the error in the respective first and second output signals.