Single-ended signals to differential signals converter

Details Single-ended signals to differential signals converter Single-ended signals to differential signals converter

1999-11-24

2001-07-10

Pascal, Robert (Department: 2817)

Amplifiers

With semiconductor amplifying device

Including balanced to unbalanced circuits and vice versa

C330S307000

Reexamination Certificate

active

06259325

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a converter for converting single-ended signals to differential signals, which is necessary for receiving an output of a single-ended signal circuit by use of a differential-end signal circuit, in particular relates to a converter of converting single-ended signals to differential signals within a monolithic integrated circuit (IC).
2. Description of the Related Art
In an analogue circuit, a single-ended signals to differential signals converter for converting single-ended signals to differential signals is a very important basic circuit.
FIG. 12
shows an existing single-ended signals to differential signals converter employing a differential amplifier.
This circuit operates as follows. That is, a single-ended input signal inputted from an input terminal is inputted to a base of a transistor Q
1
through a coupling capacitor C
1
. On the other hand, a base of a transistor Q
2
is grounded through a capacitor C
2
of identical capacitance with that of the capacitor C
1
. The transistors Q
1
and Q
2
form a transistor pair coupled to each other through an emitter and from collectors of the transistors Q
1
and Q
2
, a pair of differential signals converted from the input signal are outputted.
If this circuit operates ideally, the differential output does not contain common mode components. Accordingly, outputs of the differential signals are summed up to be a definite potential. In an actual circuit, however, there is a problem that common mode components remain between the outputs of differential signals, as a result of this, the summation of outputs of differential signals is not a definite potential. This is caused by a fact that the impedance of a bias current supply I
0
of the emitter-coupled transistor pair is not infinite in an actual circuit.
FIG. 13
is an existing single-ended signals to differential signals converter employing a transformer. In this method, a separate transformer
133
other than the first circuit
131
and the second circuit
132
is employed to implement single-ended signals to differential signals conversion. Here, to a primary coil L
1
of the transformer
133
a single-ended output terminal of the first circuit
131
is connected, and to a secondary coil L
2
of the transformer
133
a differential input terminal of the second circuit
132
.
However, in general a transformer has an area far bigger than that of a transistor or a resistor incorporated in an integrated circuit (IC). Accordingly, there is a problem that an area of circuits as a whole becomes large.
SUMMARY OF THE INVENTION
In the aforementioned existing single-ended signals to differential signals converter, there are problems that common mode components are large after conversion and a circuit itself that carries out single-ended signals to differential signals conversion is large.
An object of the present invention is to provide, without inducing an increase of a chip area of an integrated circuit, a single-ended signals to differential signals converter incorporated in an integrated circuit.
Another object of the present invention is to provide a converter for single-ended signals to differential signals conversion small in common mode components contained in the differential signals.
To these ends, a converter for single-ended signals to differential signals conversion formed within an integrated circuit involving the present invention comprises a first circuit formed within the integrated circuit, and a second circuit formed within the integrated circuit. Here, the first circuit comprises a transistor outputting single-ended signals and a first spiral inductor that is connected to an output terminal of either one of output terminals of higher voltage side and lower voltage side of the transistor as a an inductor for load use contributing to frequency performance of the first circuit. And the second circuit comprises a pair of differential input terminals inputting differential signals and a second spiral inductor that is magnetically coupled with the first spiral inductor and both ends thereof are connected to the respective differential input terminals.
According to the aforementioned means, an inductor itself that is used as a load contributing to frequency performance of the first circuit can be used as a part of the single-ended signals to differential signals converter. Accordingly, without increasing the chip area and current consumption, single-ended signals to differential signals conversion can be implemented.
A converter for single-ended signals to differential signals conversion formed within an integrated circuit of the present invention comprises a first circuit formed within the integrated circuit and a second circuit formed within the integrated circuit. Here, the first circuit is a resonant circuit in which a first spiral inductor is used as a resonator and outputs a single-ended signal. The second circuit comprises a pair of differential input terminals inputting differential signals and a second spiral inductor coupled magnetically to the first spiral inductor and both ends thereof are connected to the respective differential input terminals.
According to the aforementioned means, an inductor that is a resonator can be used as a part of a converter for single-ended signals to differential signals conversion. As a result of this, without increasing the chip area and current consumption, single-ended signals to differential signals conversion can be implemented.
Further, a converter for single-ended signals to differential signals conversion formed within an integrated circuit involving the present invention comprises a first circuit formed within the integrated circuit, and a second circuit formed within the integrated circuit. Here, the first circuit comprises a transistor outputting single-ended signals and a first and second spiral inductors that are connected to respective output terminals of a higher voltage side and a lower voltage side of the transistor as inductors for load use contributing frequency performance of the first circuit and are disposed so as to strengthen generated magnetic fluxes to each other. The second circuit comprises a pair of differential input terminals inputting differential signals and a third spiral inductor coupled magnetically to the first and second spiral inductors and both ends thereof are connected to the respective differential input terminals.
According to the aforementioned means, due to a synergistic effect between the first and second spiral inductors, upon converting differentially, conversion gain can be increased. Further, the first and second spiral inductors perform functions of impedance matching with a preceding circuit and of contribution to frequency performance of the first circuit. Accordingly, only a little bit of increase of the area of an IC chip is caused.


REFERENCES:
patent: 2192684 (1940-03-01), Crosby
patent: 3078420 (1963-02-01), Bussard
patent: 3154750 (1964-10-01), David et al.
patent: 3302125 (1967-01-01), Ulug
patent: 5793262 (1998-08-01), Kuwana
patent: 8-222439 (1996-08-01), None
John R. Long, et al. “A 1.9 Ghz Low-Voltage Silicon Bipolar Receiver Front-End for Wireless Personal Communications Systems,” IEEE Journal of Solid-State Circuits, vol. 30, No. 12, Dec. 1995, pp. 1438-1448.

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