Noise figure and linearity improvement technique using shunt feedback
AssigneePhilips Electronics North America Corporation
InventorKeng Leong Fong
Life of this patent
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Abstract
A shunt-feedback technique is provided for improving noise figure and linearity of electronic circuits, such as amplifiers and mixers. An input common-emitter transconductance stage of an electronic circuit has a transistor, and a degeneration impedance provided between the emitter of the transistor and a ground terminal. A feedback capacitor is connected between the collector and the base of the transistor. A feedback resistor is coupled between the collector of the transconductance stage transistor and the emitter of a transistor in the next stage of the electronic circuit. The feedback capacitor and the feedback resistor form a shunt-feedback network.
Claims15
An amplifier comprising:
- an input terminal for receiving an input signal to be amplified,
- a transconductance stage coupled to said input terminal for transforming power of the input signal into current,
- a cascode stage coupled to said transconductance stage to isolate an output terminal of said amplifier from said transconductance stage, and
- a frequency dependent shunt-feedback network comprising (i) feedback resistive device coupled between the transconductance stage and said cascode stare and (ii) only a feedback capacitance device coupled between said input and a node between said transconductance stage and said cascode stage, the frequency dependent shunt feedback circuit biasing the transconductance stage in dependence on the frequency of the input signal, to thereby improve noise figure of said amplifier;
- and a degeneration inductive impedance connected between an emitter of said transconductance stage and a ground terminal.
An electronic circuit comprising:
- an input terminal for receiving a first signal having first frequency,
- a transconductance stage for transforming power of said first signal to current,
- a switching stage controlled by a second signal having second frequency for producing an output signal having output frequency different from said first frequency, and
- a shunt-feedback network coupled between said input terminal and an input of said switching stage for improving linearity and noise figure of said mixer circuit.
An electronic circuit, comprising:
- an input for receiving an input signal, and an output;
- a transconductance stage coupled to said input for transforming power of the input signal into current;
- a second stage coupled between said transconductance stage and said output;
- and
- a frequency dependent shunt feedback circuit comprising (i) a feedback resistive device coupled between the transconductance stage and said second stage and (ii) only a feedback capacitance device coupled between said input and a node between said transconductance stage and said second stage, the frequency dependent shunt feedback circuit biasing the transconductance stage as a function of frequency of the input signal, to improve the noise figure of the electronic circuit;
- and a degeneration inductive impedance connected between an emitter of said transconductance stage and a ground terminal.
A narrow band RF electronic circuit, comprising:
- an input for receiving an RF input signal, and an output;
- a transconductance stage coupled to said input for transforming power of the input signal into current, said transconductance stage comprising a first bipolar transistor having a base coupled to said input, a collector and an emitter;
- a second stage coupled between said transconductance stage and said output, said second stage comprising a second bipolar transistor having a base, a collector coupled to the output, and an emitter;
- and
- a frequency dependent shunt feedback circuit comprising (i) a feedback resistive device coupled between said collector of said first transistor and said emitter of said second transistor and (ii) a feedback capacitive device coupled between said base of said first transistor and said feed feedback resistive device, the frequency dependent shunt feedback circuit biasing the transconductance stage as a function of frequency of the input signal, to improve the noise figure of the electronic circuit;
- and
- a degeneration inductive impedance connected between said emitter of said first transistor and a ground terminal.
Dependencies are inferred from the claim text.