|Publication number||US20060022769 A1|
|Application number||US 11/206,001|
|Publication date||Feb 2, 2006|
|Filing date||Aug 18, 2005|
|Priority date||Jan 31, 2002|
|Also published as||US6965269, US20040041664, WO2003065494A1|
|Publication number||11206001, 206001, US 2006/0022769 A1, US 2006/022769 A1, US 20060022769 A1, US 20060022769A1, US 2006022769 A1, US 2006022769A1, US-A1-20060022769, US-A1-2006022769, US2006/0022769A1, US2006/022769A1, US20060022769 A1, US20060022769A1, US2006022769 A1, US2006022769A1|
|Original Assignee||Hideki Takasu|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Referenced by (2), Classifications (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This is a divisional application of, and claims priority to, U.S. Ser. No. 10/634,887, filed Aug. 6, 2003, which is a Continuation Application of PCT Application No. PCT/JP03/00852, filed Jan. 29, 2003, which was not published under PCT Article 21(2) in English.
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-023487, filed Jan. 31, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a microwave phase shifter which gives a desired phase shift amount to a high-frequency signal and a power amplifier using the microwave phase shifter.
2. Description of the Related Art
A microwave phase shifter is a circuit which gives a preset phase shift amount to a high-frequency signal of microwave, millimeter wave or the like and is normally configured by combining several transmission lines, a switch circuit and the like. For example, it has a transmission line used as a reference and transmission lines having delay amounts corresponding to preset phase differences with respect to the reference side transmission line, and a phase shift amount corresponding to the phase difference with respect to the reference is acquired by selecting one of the transmission lines by use of the switch circuit.
The microwave phase shifter with the above configuration is formed in an IC form by forming a plurality of transmission lines with different delay amounts and a switch circuit to switch the transmission lines on a substrate and thus an attempt is made to make the whole device small. However, since the switch circuit simultaneously makes selection of and switching to a single line from a plurality of lines on the input side and output side, a plurality of switch elements and driving control circuits are required. As a result, the circuit configuration of the microwave phase shifter formed on the substrate becomes complicated, the substrate becomes larger and the cost rises due to an increase in the number of manufacturing steps.
In the latest microwave communications devices for satellite communications, mobile communications, etc, a power amplifier using a semiconductor amplifier element is used, from the viewpoint of size, weight, reliability, etc. In a power amplifier using this semiconductor amplifier element, the output power which can be acquired by use of one element is not necessarily sufficient. Therefore, a power synthesizing type of power amplifier is proposed which, when a high output power is required, distributes an input signal into plural paths, amplifies them by use of semiconductor amplifier elements while controlling the signal phases, and then re-synthesizes the signals (for example, Jpn. Pat. Apln. KOKAI Publication No. 2001-196870 (p 5, FIG. 1)).
In the power amplifier, since a power loss occurs if the phases of the signals are deviated at the time of power synthesis, the phase differences between the signals are eliminated and the loss at the time of power synthesis is reduced by inserting phase shifters into paths other than a path used as a reference to adjust the phases. Thus, in the power synthesizing type of power amplifier, phase shifters corresponding in number to (the number of distributions—1) are required. Therefore, in order to make the power amplifier small and sufficiently reduce the loss, a phase shifter which is small and inexpensive and can relatively easily and precisely adjust the phase shift amount is desired.
An object of this invention is to provide a microwave phase shifter in which the circuit configuration is simple and can be easily made small, and as a result, the manufacturing cost can be lowered, and which can relatively easily and precisely adjust a phase shift amount, and a power synthesizing type of power amplifier using the microwave phase shifter.
A microwave phase shifter of this invention comprises a semi-insulating substrate having an operating layer partly formed thereon, a signal conductor formed on the operating layer of the semi-insulating substrate, a grounding conductor formed on the same surface as the signal conductor on the semi-insulating substrate, and a bias power supply which applies a bias voltage to the signal conductor.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.
There will now be described embodiments of this invention with reference to the accompanying drawings.
On the upper side of the active layer 112, a transmission line 114 of a metal material is formed. Further, on the surface of the semi-insulating layer 111 on which the transmission line 114 is formed, a second conductive layer 115 having an end portion formed to extend along and in close proximity to one side (right side in the drawing) of the transmission line 114 is formed.
In the circuit board 11 with the above configuration, the first conductive layer 113 and second conductive layer 115 are connected to a ground terminal 116 (the first conductive layer and second conductive layer are hereinafter referred to as a first grounding conductive layer and second grounding conductive layer, respectively), and the transmission line 114 is connected to a bias voltage input terminal 117. To the terminal 117, bias voltage Vp of negative polarity is applied from a bias power supply 12 on the external portion of the phase shifter. In this case, reverse bias is applied to the active layer 112 which lies directly under the transmission line 114. As a result, a depletion layer is formed in the active layer 112 and capacitance is equivalently connected to the transmission line 114. Further, if the value of the bias voltage is changed, the extent of the depletion layer varies. Therefore, the capacitance value caused by forming the depletion layer varies based on the function of the bias voltage.
In this case, the characteristic impedance Z0 of the micro-coplanar strip line is determined by the equation (1).
Z 0=[1/(c+c 1)]1/2 (1)
Therefore, the phase θ of a microwave signal (angular frequency ω)) which propagates along the transmission line 114 with line length L is given by the equation (2) if β=ω·Z0.
θ=βL=ω[1/(c+c 1)]1/2 ×L (2)
As described before, the value of the capacitance c1 varies if the bias voltage Vp applied to the transmission line 114 is changed. Therefore, as is clearly seen from the equation (2), it becomes possible to change the propagation phase θ of the transmission line 114 by changing the bias voltage Vp.
For example, if a reference phase (θ1) is obtained when the bias voltage Vp is 0 [V] and a phase is set to θ2 when the bias voltage Vp is v, phase difference Δθ indicated by the equation (3) can be obtained.
In this case, it is operated as a phase shifter with the phase shift amount Δθ.
From the above description, according to the configuration of the present embodiment, since a switch circuit to switch transmission lines becomes unnecessary and the phase shift amount can be set only by the bias voltage applied to the transmission line, the circuit configuration is made simple. Further, since the phase difference Δθ is determined by the value of the bias voltage Vp, the phase shift amount can be controlled in a continuous or stepwise fashion by changing the bias voltage in a continuous or stepwise fashion.
A circuit board 11 shown in
However, in the present embodiment, no active layer is formed.
With the above configuration, if bias voltage Vp is applied to the transmission line 114, voltages are applied to the liquid crystal dielectric layer 118 between the transmission line 114 and the first grounding conductive layer 113 and between the transmission line 114 and the second grounding conductive layer 115. As a result, in the liquid crystal dielectric layer 118, the directivity of an anisotropic dielectric is changed. The directivity is changed according to the value of the bias voltage Vp. Therefore, if the value of the bias voltage Vp is changed, values of parasitic capacitances caused between the transmission line 114 and the first grounding conductive layer 113 and between the transmission line 114 and the second grounding conductive layer 115 vary.
In this case, the characteristic impedance Z0 of the micro-coplanar strip line is determined by the equation (4).
Z 0=(1/c)1/2 (4)
Therefore, the phase θ of a microwave signal (angular frequency ω) which propagates along the transmission line 114 with line length L is given by the equation (5) if β=ω·Z0.
θ=βL=ω(1/c)1/2 ×L (5)
As described before, if the bias voltage Vp applied to the transmission line 114 is changed, the dielectric constant of the liquid crystal dielectric layer 116 varies and the value of the capacitance c varies. Therefore, as is clearly seen from the equation (5), it becomes possible to change the propagation phase θ of the transmission line 114 by changing the bias voltage Vp.
For example, if a reference phase (θ1) is obtained when the bias voltage Vp is 0[V] and a phase is set to θ2 when the bias voltage Vp is v, phase difference Δθ indicated by the equation (6) can be obtained.
In this case, it is operated as a phase shifter with the phase shift amount Δθ.
From the above description, also, according to the configuration of the present embodiment, since a switch circuit to switch transmission lines becomes unnecessary and the phase shift amount can be set only by the bias voltage applied to the transmission line, the circuit configuration is made simple. Further, since the phase difference Δθ is determined by the value of the bias voltage Vp, the phase shift amount can be controlled in a continuous or stepwise fashion by changing the bias voltage in a continuous or stepwise fashion.
The power amplifier of the above configuration is a so-called power synthesizing type, and it evenly matches the phases when power-amplifying the distributed microwave signals and adds and synthesizes the power-amplified outputs. In the present embodiment, as the phase shifter 24 to make a phase adjustment, the microwave phase shifter with the configuration of the first or second embodiment is used.
The power value of the synthesis signal supplied to the output terminal 26 is monitored by a power monitoring device 28 and the monitoring result is supplied to a control device 29. The control device 29 controls the phase shift amount of the phase shifter 24 so that the monitoring power value is maximum. The control is to supply the bias voltage Vp to a bias voltage input terminal of the phase shifter 24 and change the bias voltage Vp according to the phase shift amount.
Since the power amplifier with the above configuration uses the microwave phase shifter of the first or second embodiment in the phase shifter 24, it can be made small and the cost can be lowered. Further, since the phase shift amount of the phase shifter 24 can be adjusted continuously or in fine steps, it can be adjusted with high precision in comparison with the conventional line switching system.
In the power amplifier of the above embodiment, the phase shifter 24 is incorporated in the preceding stage of the amplifier 25 in each distribution path, but since the configuration of the phase shifter of this invention is excellent in the power-resistance characteristic, it can be arranged in the succeeding stage of the amplifier 25 as shown in
Further, in the above embodiment, the amplifier 25 and the phase shifter 24 are explained as different units, but the configuration of the phase shifter 24 can be incorporated into the amplifier 25 itself. With this configuration, the size can be further reduced.
Further, in the above embodiment, the number of distribution paths is two, but when the number of distribution paths is increased, the phases of transmission signals of the respective paths can be similarly matched by using one path as a reference path and arranging phase shifters in other paths. Of course, the same operation can be performed even when a phase shifter is arranged in the reference path.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3560891 *||Mar 24, 1969||Feb 2, 1971||Westinghouse Electric Corp||Reflection phase shifter utilizing microstrip directional coupler|
|US4630011 *||Dec 12, 1985||Dec 16, 1986||The United States Of America As Represented By The Secretary Of The Navy||Microwave and millimeter wave phase shifter|
|US5083100 *||Feb 26, 1991||Jan 21, 1992||Digital Equipment Corporation||Electronically variable delay line|
|US5576671 *||Apr 24, 1995||Nov 19, 1996||Motorola, Inc.||Method and apparatus for power combining/dividing|
|US5777531 *||Jun 26, 1996||Jul 7, 1998||Texas Instruments Incorporated||Semiconductor coplanar waveguide phase shifter|
|US5936484 *||Feb 24, 1995||Aug 10, 1999||Thomson-Csf||UHF phase shifter and application to an array antenna|
|US6076001 *||Jun 5, 1997||Jun 13, 2000||Das; Satyendranath||High superconducting ferroelectric CPW variable time delay devices|
|US6965269 *||Aug 6, 2003||Nov 15, 2005||Kabushiki Kaisha Toshiba||Microwave phase shifter having an active layer under the phase shifting line and power amplifier using such a phase shifter|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7401315 *||Nov 14, 2005||Jul 15, 2008||Avago Technologies General Ip Pte Ltd||System and method for implementing package level IP preverification for system on chip devices|
|WO2014022688A1 *||Aug 1, 2013||Feb 6, 2014||Samtec, Inc.||Multi-layer transmission lines|