Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1988-07-08
1990-03-13
Steinberger, Brian S.
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
328155, H03L 700
Patent
active
049085328
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a quadrature signal generator. Apparatus such as phasing single side band generators, direct conversion receivers and some radar receiving systems require the production of "In-phase" and "Quadrature phase" channels (I and Q channels). The signals in the two channels have a 90.degree. phase difference between them.
BACKGROUND ART
It is known to produce I and Q channel signals in various ways. For example, a known method uses a transmission line quadrature hybrid incorporating wound components which make it unsuitable for fabrication by integrated circuit technology. Alternatively, at ultra high frequencies (UHF), striplines may be used. Such hybrids suffer from the disadvantage in that they are, essentially, narrow band devices. A second known method uses a digital divider. However, as the divider employs digital techniques, it cannot handle quadrature phase shift at low levels or where the signal amplitudes vary to any great extent.
A further known method is that utilising a resistance-capacitance network to produce the required phase shift. Such a network is shown diagrammatically in FIG. 1 of the accompanying drawings. The network comprises two arms 10, a first arm containing a resistor R.sub.1 and a capacitor C.sub.1, and a second arm containing a resistor R2 and a capacitor C.sub.2. Providing R.sub.1.C.sub.1 is equal to C.sub.2.R.sub.2, a signal applied at V.sub.APP will be split into two signal channels in quadrature phase, a first signal channel being advanced in phase by 45.degree. and the second signal channel being retarded in phase by 45.degree.. The values of the resistors R.sub.1, R.sub.2 and of the capacitors C.sub.1, C.sub.2 are chosen for the specific frequency of the applied signal. Although of low cost and offering an acceptable tolerance sensitivity (of the designed frequency), variations in the frequency of the applied signal cause relatively high losses in the network, and hence, it is essentially a narrow bandwidth device if the network loss is not to exceed 3 dB.
In general, quadrature signal generators have an accuracy tolerance which depends on the tolerance of the components forming the circuit. In integrated circuits, because of their small size, high accuracy of component values is extremely difficult to achieve.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a quadrature signal generator of low cost, suitable for fabrication by integrated circuit technology, which has an increased bandwidth without substantially increasing the losses involved or producing variations in the desired 90.degree. phase difference.
According to the present invention, there is provided a quadrature signals generator, responsive to an applied input signal, for producing two phase-shifted output signals differing from each other by a relative phase of 90.degree.;
said generator including a phase-shifting network, this network being interconnected between signal input and ground, and, having essentially a pair of arms each of which is comprised of a resistor, an output channel, and a capacitance element in series therewith;
said generator being characterised by:
a phase detector, having inputs connected to respective output channels of the network, responsive to any difference from 90.degree. relative phase between said two output signals, to produce a control error signal; and, said capacitance elements being of variable type and arranged relative to said detector to allow variation of the capacitance in both network arms so to maintain the two output signals in quadrature relative phase.
INTRODUCTION OF THE DRAWINGS
The invention will be described further, by way of example, with reference to FIG. 2 of the accompanying drawing which is a schematic diagram of a quadrature signals generator according to the present invention.
DESCRIPTION OF A PREFERRED EMBODIMENT
As shown in FIG. 2, the quadrature signals generator according to a preferred embodiment of the present invention employs a resistance-capacitance network 12
REFERENCES:
patent: 3614475 (1971-10-01), Deboo
patent: 4021740 (1977-05-01), Horna
patent: 4475088 (1984-10-01), Beard
Proc. IEE, vol. 122, No. 9, Sep. 1975; D. Woods: "Passive Network as a Complex-Voltage Generator in Four Quadrants", pp. 947-950.
Plessey Overseas Limited
Steinberger Brian S.
LandOfFree
Quadrature signals generator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Quadrature signals generator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quadrature signals generator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-52391