Gain enhancement for amplifier using a replica amplifier

An amplifier assembly for coupling to an input source which provides-a first amplifier input signal at an amplifier input lead and for providing an amplified output signal at an amplifier output lead in response thereto, the assembly comprising:

• an amplifier having
• a first stage for receiving an input signal derived from the first amplifier input signal and for providing a first stage output signal,
• a second stage for receiving the first stage output signal and for providing the amplified output signal, and
• a feedback network for directly coupling the amplifier output lead and the amplifier input lead;
• a correction circuit for receiving a second amplifier input signal which is substantially similar to the first amplifier input, and for providing a correction circuit output signal that is independent of the first feedback network;
• and
• means for combining the correction circuit output signal and the first stage output signal and for providing the combined output signal to the second stage.

An amplifier assembly for coupling to an input source which provides a first amplifier input signal and for providing an amplified output signal in response thereto, the assembly comprising:

• an amplifier having
• a first stage for receiving an input signal derived from the first amplifier input signal and for providing a first stage output signal,
• a second stage for receiving the first stage output signal and for providing the amplified output signal, and
• a feedback network for coupling the amplified output signal and the amplifier input signal;
• a correction circuit for receiving a second amplifier input signal which is substantially similar to the first amplifier input, and for providing a correction circuit output signal;
• and
• means for combining the correction circuit output signal and the first stage output signal and for providing the combined output signal to the second stage;
• wherein the correction circuit comprises:
• first and second stages which are substantially similar to the first and second stages of the amplifier, respectively, and
• a coupling stage, the first stage of the correction circuit and the coupling stage each receiving an input signal derived from the amplifier input signal wherein the output of the coupling stage being the correction circuit output signal.

An amplifier assembly for coupling to an input source which provides a first amplifier input signal at an amplifier input lead and for providing an amplified output signal at an amplifier output lead in response thereto, the assembly comprising:

• an amplifier having
• a first stage for receiving an input signal derived from the first amplifier input signal and for providing a first stage output signal,
• a second stage for receiving the first stage output signal and for providing the amplified output signal, and
• a feedback network for coupling the amplifier output lead and the amplifier input lead;
• a correction circuit for receiving a second amplifier input signal which is substantially similar to the first amplifier input, and for providing a correction circuit output signal;
• and
• means for combining the correction circuit output signal and the first stage output signal and for providing the combined output signal to the second stage, wherein the correction circuit output signal is about the same as the first stage output would have been without the correction circuit being coupled.

An amplifier assembly for coupling to an input source which provides a first amplifier input signal and for providing an amplified output signal in response thereto, the assembly comprising:

• an amplifier having
• a first stage for coupling to the input source for receiving an input signal derived from the first amplifier input signal and for providing a first stage output signal,
• a second stage for receiving the first stage output signal and for providing the amplified output signal, and
• a feedback network for coupling the amplified output signal and the first amplifier input signal;
• a correction circuit for receiving a second amplifier input signal similar to the first amplifier input signal, and for providing a correction circuit output signal independent of the feedback network;
• and
• means for combining the correction circuit output signal and the first stage output signal and for providing the combined output signal to the second stage,
• wherein the correction circuit output signal is much larger than the first stage output signal.

The assembly of claim 25 wherein

• the first stage of the correction circuit has a transfer function A,
• the second stage of the correction circuit has a transfer function B,
• the coupling stage has a transfer function C, and the second stage of the amplifier has a transfer function D;
• and wherein
• f(A, B) =f(C, D).

An amplifier assembly for coupling to an input source and for providing an amplified output signal in response thereto comprising:

• an amplifier having
• a first stage for coupling to the input source for receiving an input signal and for providing a first stage output signal,
• a second stage for receiving the first stage output signal and for providing an output signal from which the amplified output signal is derived, and
• a feedback network for coupling the amplified output signal and the input signal;
• a correction circuit having
• a first stage for receiving an input signal similar to the input signal received by the first stage of the amplifier and for providing a first stage correction output signal independent of the feedback network, and
• means for splitting the first stage correction output signal into a coupling signal and a noncoupling signal;
• and
• means for combining the coupling signal and the first stage output signal and for providing the combined output signal to the second stage.

An amplifier assembly comprising:

• an amplifier for receiving an amplifier input from an input source at an input lead and for providing an amplified output at an output, lead the amplifier having
• a first amplifying stage including
• a first transconductance stage for receiving a first stage voltage input which is derived from the amplifier input and for providing a first output current,
• a first output resistance stage for receiving a first input current and for providing the first stage voltage output,
• a second amplifying stage including
• a second transconductance stage for receiving the first stage voltage output as an input signal, and for providing a second stage output current, and
• a second output resistance stage for receiving a second input current derived from the second stage output current and for providing the amplified output, and
• a first feedback network for directly coupling the input lead and the output lead;
• a correction circuit for receiving the amplifier input at an input lead and for providing a correction circuit output combined current at a first output lead and a second amplified output voltage signal at a second output lead;
• and
• means for combining the correction circuit output current and the first stage output current and for providing the current as the first input current to the first output resistance stage.

An amplifier assembly comprising:

• an amplifier for receiving an amplifier input from an input source at an input terminal and for providing an amplified output at an output terminal, the amplifier having
• a first amplifying stage including
• a first transconductance stage for receiving a first stage voltage input which is derived from the amplifier input and for providing a first output current,
• a first output resistance stage for receiving the first output current and for providing the first stage voltage output,
• a second amplifying stage including
• a second transconductance stage for receiving the first stage voltage output as an input, and for providing a second stage output current, and
• a second output resistance stage for receiving the second stage output current and for providing the amplified output, and
• a first feedback network for coupling the input terminal and the output terminal;
• a correction circuit for receiving the amplifier input and for providing a, correction circuit output current;
• and
• means for combining the correction circuit output current and the second stage output current and for providing the combined current to the second output resistance stage.

An amplifier assembly comprising:

• a first amplifier for receiving an amplifier input signal from an input source and for providing a first amplified output signal in response thereto, the first amplifier including:
• a transconductance stage for receiving a first input signal which is derived from the amplifier input signal, and for providing a first output signal at an output lead in response thereto, and
• an output resistance stage for receiving an input signal derived from the first output signal and for providing an output signal;
• a first feedback network coupled to the first amplifier, the first feedback network connecting the amplified output signal and the amplifier input signal;
• a second amplifier for receiving a second amplifier input signal derived from the input source and for providing a second amplified output signal in response thereto, the second amplifier including a transconductance stage for receiving a signal derived from the second amplifier input signal and for providing an output current in response thereto;
• and
• a current splitter for receiving a current derived from the output current and for providing a first output current and a second output current, the first output current being coupled to the first amplifier in order to be combined with the first output signal of the first amplifier, the second amplifier output signal being derived from the second output current.

An amplifier assembly comprising:

• a first amplifier having an input lead for receiving an input signal, and for providing an amplified output at an amplifier output lead in response thereto, the first amplifier including:
• a first differential stage having a first input lead for receiving an input voltage derived from the input signal, the first differential stage for providing a first output voltage, and
• a first transconductance stage for receiving a voltage derived from the first output voltage, and for providing a first output current in response thereto;
• a second amplifier including:
• a second differential stage having a first input lead for receiving a second input voltage derived from the input signal, the second differential stage for providing a second output voltage, and
• a second transconductance coupling stage for receiving a voltage derived from the second output voltage, and for providing a second output current,
• the first and second output currents being combined by a summing node, wherein the amplifier output signal is derived from the sum of the first and second output currents.

A circuit for coupling to an amplifier to increase the gain of the, amplifier, the amplifier for receiving an input signal at an amplifier input lead and for providing an amplified voltage signal and at an amplifier output lead, the amplifier having a first stage for receiving a first input voltage signal and for providing a first output voltage signal in response thereto, and a first transconductance stage for receiving an input voltage signal derived from the first output voltage and for providing a first output current in response thereto, wherein the amplified voltage signal is derived from the first output current when the amplifier is not coupled to the circuit so that the amplifier has a first open loop gain, the circuit comprising:

• an input lead for coupling to an input source for receiving a second input voltage signal derived from the input source;
• means for receiving an input voltage signal derived from the second input voltage signal and for providing a second output current in response thereto, the second output current being substantially equal to the first output current when the circuit is not coupled to the amplifier;
• and
• means for combining the first output current and the second output current to produce a combined output current, wherein the amplified voltage signal is derived from the combined output current and has a second open loop gain, wherein the second open loop gain is substantially greater than the first open loop gain.