Image canceling mixer circuit on an integrated circuit chip

Details Image canceling mixer circuit on an integrated circuit chip Image canceling mixer circuit on an integrated circuit chip

1989-08-30

1992-08-18

Callahan, Timothy P.

Electrical transmission or interconnection systems

Nonlinear reactor systems

Parametrons

307520, 328165, 455302, H04B 110, H04B 126

Patent

active

051401983

ABSTRACT:
An IF mixer circuit in a receiver implemented in integrated circuits employs a pair of doubly balance mixers, one injected with a local oscillator reference signal in phase while the quadrature phase of the reference signal is injected into the second mixer. A phase shift circuit adds another 90.degree. phase shift to the output of the second mixer, and the in-phase and out-of-phase signals are applied to a summing circuit to attenuate unwanted mixer products and reinforce the desired IF signal. The balanced elements of the 90.degree. phase shift circuit employ a transistor with equal emitter and collector resistances, a diode-connected transistor in series with the collector load resistance, and a collector-to-base capacitor, which provide a constant-amplitude phase shift in a unity gain structure independent of current, to produce a precise 90.degree. phase shift. Emitter current is adjustable to compensate for production variation in the absolute value of the fixed resistance, i.e., by varying the current in the transistor and diode, the dynamic resistance offsets the fixed resistance variation.

REFERENCES:
patent: 4349916 (1982-09-01), Roeder
patent: 4414686 (1983-11-01), Lenz
patent: 4584715 (1986-04-01), Baars et al.
patent: 4696055 (1987-09-01), Marshall
patent: 4710975 (1987-12-01), Okamoto et al.
Howell et al., "Image-Cancelling Mixers", Electronic Letters, Jul. 13, 1972, vol. 18, No. 14, pp. 352-354.

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