Low noise analog multiplier utilizing nonlinear local feedback elements
OwnerRonald Quaninventor
Life of this patent
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Abstract
A voltage controlled amplifier is improved in noise performance with nonlinear local feedback elements while maintaining low distortion for various control settings. By paralleling nonlinear elements, distortion is further improved. Preferably, these nonlinear elements consist of diode pairs connected to the emitters of a differential amplifier whereby the bases of the transistors are used to control the signal current.
Claims37
A method of reducing the output noise generated by a gain controlled amplifier, analog mixer or multiplier circuit, wherein the circuit includes a pair of output transistors having an emitter, collector and base, comprising:
- inserting one or more nonlinear element with local feedback in series with at least one of the output transistors;
- and
- applying a linearizing control voltage to at least one of the output transistors to linearize the control input of said circuit.
A method of reducing distortion while lowering noise at the output of a voltage controlled amplifier, mixer or multiplier circuit, which circuit includes local feedback elements and output transistors having an emitter, collector and base and corresponding series emitter and base series resistances, comprising:
- supplying a signal current to a respective output transistor;
- applying a derived output signal current to a load resistor to supply an output signal from said circuit;
- providing a control voltage for said circuit;
- and
- applying a portion of the output signal and the control voltage to a base of at least one of the output transistors to effectively lower the equivalent series emitter and/or internal base series resistance.
Apparatus for reducing the distortion while maintaining or reducing the noise at the output of voltage controlled amplifier, mixer or multiplier circuit, wherein said circuit includes output transistors having an emitter, collector and base, comprising:
- a signal circuit integral with the amplifier, mixer or multiplier circuit for providing a signal current to the output transistors;
- at least one nonlinear local feedback element inserted in series with a respective output transistor for receiving the signal current;
- means for generating a signal voltage from said circuit by applying a derived output signal current to a load resistor to thereby generate the signal voltage;
- means for providing a control voltage;
- and
- means for applying a portion of the signal voltage and the control voltage to the base of at least one of the output transistors to effectively reduce the distortion while reducing or maintaining the noise.
A method of reducing noise while at least maintaining distortion at the output of a voltage controlled amplifier, mixer or multiplier circuit, which circuit includes a pair of output transistor having an emitter, collector and base, comprising:
- passing the emitter currents of the output transistors through respective nonlinear elements disposed in series with the emitters;
- wherein a nonlinear element includes a plurality of diodes configured in series;
- and
- wherein the plurality of diodes further includes one or more sets of parallel diodes configured in series or at least two serial diodes in paralleled strings of diodes.
Apparatus for reducing the noise while maintaining or reducing the distortion, at the output of a voltage controlled amplifier, mixer or multiplier circuit, wherein the circuit includes output transistors having an emitter, collector and base, comprising:
- a signal circuit for providing a signal current to the output transistors;
- at least one nonlinear element inserted in series with a respective output transistor for receiving the signal current;
- means for applying a control voltage to the base of at least one of the output transistors;
- and
- wherein the nonlinear element includes one or more sets of parallel diodes inserted in series with the emitter of an output transistor.
Apparatus for reducing the output noise of a voltage controlled amplifier which includes output transistors having an emitter, collector and base, comprising:
- a linear resistance inserted in series with an emitter of at least one of the output transistors;
- current sensing and scaling means for sensing and scaling a differential output current of the voltage controlled amplifier;
- means for applying a control voltage to a base of an output transistor;
- and
- selectively supplying the scaled output current into a load resistor with the control voltage.
A method of reducing the output noise generated by gain controlled amplifier, analog mixer of multiplier circuits, wherein the circuit includes a pair of output transistors having an emitter, collector and base, comprising:
- inserting one or more non-linear element with local feedback in series with at least one of the output transistors;
- and
- wherein the non-linear element includes a linear element.
A method of reducing the output noise generated by gain controlled amplifier, analog mixer of multiplier circuits, wherein the circuit includes a pair of output transistors having an emitter, collector and base, comprising:
- inserting one or more non-linear element with local feedback in series with at least one of the output transistors;
- and
- wherein the non-linear element comprises one or more sets of parallel diodes in series with an output transistor.
A method of reducing the output noise generated by gain controlled amplifier, analog mixer of multiplier circuits, wherein the circuit includes a pair of output transistors having an emitter, collector and base, comprising:
- inserting one or more non-l near element with local feedback in series with at least one of the output transistors;
- and
- wherein the non-linear element comprises parallel strings of multiple serial diodes configured in series with an output transistor.
Apparatus for reducing the noise while maintaining or reducing the distortion, at the output of a voltage controlled amplifier, mixer or multiplier circuit, wherein the circuit includes output transistors having an emitter, collector and base, comprising:
- a signal circuit for providing a signal current to the output transistors;
- at least one nonlinear element inserted in series with a respective output transistor for receiving the signal current;
- means for applying a control voltage to the base of at least one of the output transistors;
- and
- wherein the nonlinear element includes paralleled strings of multiple serial diodes inserted in series with the emitter of an output transistor.
A method of reducing or removing distortion in a differential voltage controlled amplifier having an input receiving a control voltage, and local feedback elements including resistances which cause the distortion, comprising:
- providing an output current from the voltage controlled amplifier;
- applying the output current to a load resistor to generate an output voltage;
- and
- applying a combination of the control voltage and at least a portion of the output voltage of the voltage controlled amplifier to the control input of the voltage controlled amplifier.
A method reducing or removing distortion in a field effect transistor (FET) voltage controlled amplifier mixer or multiplier circuit having an input receiving a control voltage and which may or may not have local feedback elements, comprising:
- providing a signal current from a portion of the output or outputs of said circuit;
- applying the signal current to a load resistor to generate a signal voltage;
- and
- applying a combination of the signal voltage and control voltage to the gate of at least one the FETS.
Dependencies are inferred from the claim text.