Differential transconductance amplifier

A differential transconductance amplifier circuit comprising:

• a transistor differential pair, each transistor having a base, an emitter and a collector,
• an alternating current input port including first and second lines receiving alternating current at a frequency with the first alternating current line tied to the base of one of the transistors and the second alternating current line tied to the base of the other of the transistors,
• a degeneration feedback circuit connecting the emitters of the transistors and including two inductive impedances with a capacitive impedance between them, the inductive and capacitive impedances having values so as to resonate at about the frequency of the alternating current and a resistance in series with the series of inductive and capacitive impedances to de-Q resonance of the series of inductive and capacitive impedances, and
• bias current sources connected between the capacitive impedance and each of the inductive impedances so that the emitter currents of the differential amplifier transistors are the currents in the bias current sources.

A differential transconductance amplifier for a radio frequency circuit comprising a Gilbert cell including:

• a. first and second pairs of transistors,
• b. an intermediate frequency port including first and second lines, with the second intermediate frequency line tied to a collector of one transistor of each pair and the first intermediate frequency line tied to a collector of the other transistor of each pair,
• c. a local oscillator port including first and second lines, with the second oscillator line tied to a base of one transistor of each pair and the first oscillator line tied to a base of the other transistor of each pair, and
• d. a differential amplifier including
• i) a third pair of transistors,
• ii) a collector of each of the transistors of the third pair of transistors being electrically connected to tied emitters of one of the first and second pairs of transistors,
• iii) a radio frequency port including first and second lines with the first radio frequency line tied to a base of one of the third pair of transistors and the second radio frequency line tied to a base of the other of the third pair of transistors, and
• iv) a degeneration circuit that connects emitters of the third pair of transistors and includes
• a) a series of inductive and capacitive impedances, including two inductive impedances with a capacitive impedance between them, wherein the series of inductive and capacitive impedances have values so as to resonate at about the frequency on the radio frequency lines,
• b) a resistance in series with the series of inductive and capacitive impedances to de-Q resonance of the series of inductive and capacitive impedances, and
• c) conductors connected between the capacitive impedance and each of the inductive impedances so that the emitter currents of the differential amplifier transistors are determined by currents in the conductors.

A method of differential amplification comprising:

• providing a transistor differential pair with a signal across their collectors,
• supplying alternating current at a frequency at the bases of the transistors,
• supplying current at the emitters of the transistors from two current sources through inductive impedances, and
• capacitively coupling the current sources to permit resonance between the emitters.

A method of differential amplification comprising:

• providing a differential pair of field effect transistors,
• supplying alternating current at a frequency at the gates of the transistors,
• supplying current at the sources of the transistors from two current sources through inductive impedances, and
• capacitively coupling the current sources to permit resonance between the sources of the transistors.