US 5,715,532 AGranted

Frequency converter apparatus with distortion compensating circuit

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsMorikazu Sagawa, Keiichirou Kuwaduru, Kazuaki Takahashi, Yoshikazu Mori

Life of this patent

Estimating the term…

Loading patent…

Abstract

A frequency converter may be employed in communication equipment such as a portable telephone. The frequency converter includes a differential pair consisting of first and second transistors, a current bypass circuit consisting of third and fourth transistors, and a distortion compensating circuit consisting of fifth and sixth transistors. The distortion compensating circuit decreases an emitter-to-base voltage of the sixth transistor when an emitter current of the first transistor is increased, while it increases an emitter-to-base voltage of the fifth transistor when an emitter current of the second transistor is decreased, non-linearts components of the emitter-to-base voltages of the first and second transistors caused by variations of RF (radio-frequency) signals inputted to the first and second transistors are called decreasing distortion of an output signal of the frequency converter caused by the difference in operating point between the first and second transistors.

Claims18

Dependent claims

A frequency converter apparatus comprising:

a differential pair including first and second transistors into which a first signal is inputted to a base of the first and second transistors:
a current bypass circuit including third and fourth transistors, into which a second signal different from said first signal is inputted, bases of the third and fourth transistors being connected to each other, an emitter of the third transistor being connected in series with an emitter of the first transistor, an emitter of the first transistor being connected in series with an emitter of the second transistor wherein the second signal is applied to a base of said third and fourth transistors;
an output load circuit disposed so as to connect a power source to said differential pair and said current bypass circuit;
a distortion compensating circuit including fifth and sixth transistors, a collector of the fifth transistor and a base of the sixth transistor being connected to the emitters of the first and third transistors, a base of the fifth transistor and a collector of the sixth transistor being connected to the emitters of the second and fourth transistors;
a current source circuit connected to emitters of the fifth and sixth transistors;
and
a resistor disposed between the emitters of the fifth and sixth transistors wherein said first and second signals are mixed to produce an output signal from said first and second transistors.

4 more elements

A frequency converter apparatus comprising:

a differential pair including first and second transistors to which a first signal is inputted to an emitter of at least one of said first and second transistors;
a current bypass circuit including third and fourth transistors, into which a second signal is inputted, bases of the third and fourth transistors being connected to each other and conducted to receive said second signal, an emitter of the third transistor being connected in to an emitter of the first transistor, an emitter of the fourth transistor being connected to an emitter of the second transistor;
an output load circuit disposed so as to connect a power source to said differential pair and said current bypass circuit;
a distortion compensating circuit including fifth and sixth transistors, a collector of the fifth transistor and a base of the sixth transistor being connected to a junction of the emitters of the first and third transistors, a base of the fifth transistor and a collector of the sixth transistor being connected to the emitters of the second and fourth transistors;
a current source circuit connected to emitters of the fifth and sixth transistors;
and
a resistor disposed between the emitters of the fifth and sixth transistors wherein said first and second signals are mixed to produce an output signal from said first and second transistors of said differential pair.

4 more elements

A frequency converter apparatus comprising:

a first frequency converter circuit;
a second frequency converter circuit;
and
an output load circuit,
wherein each of said first and second frequency converter circuits includes
(1) a differential pair including first and second transistors into which a first signal is inputted on a base of said first and second transistors,
(2) a current bypass circuit including third and fourth transistors, into which a second signal is inputted, bases of the third and fourth transistors being connected to each other and to receive said second signal, an emitter of the third transistor being connected in series with an emitter of the first transistor, an emitter of the fourth transistor being connected in series with an emitter of the second transistor,
(3) a distortion compensating circuit including fifth and sixth transistors, a collector of the fifth transistor and a base of the sixth transistor being connected to the emitters of the first and third transistors, a base of the fifth transistor and a collector of the sixth transistor being connected to the emitters of the second and fourth transistors;
(4) a current source circuit connected to emitters of the fifth and sixth transistors, and
(5) a resistor disposed between the emitters of the fifth and sixth transistors,
wherein said first and second frequency converter circuits are connected so as to mix same phase output signal components of said first and second signals provided thereby, and
wherein said output load circuit is disposed so as to connect a power source to said differential pair and said current bypass circuit of each of said first and second frequency converter circuits.

9 more elements

Dependencies are inferred from the claim text.