DE102010005549A1 - High-frequency output signal phase shift or adjustment method for active array antenna, involves setting phase of reference oscillator signal and/or phase of local oscillator signal for displacement and/or setting of phase of output signal - Google Patents

Abstract

The method involves mixing an output signal produced of a tunable oscillator i.e. voltage-controlled oscillator (2), with a local oscillator signal. A phase of the output signal of the tunable oscillator is controlled as a function of a phase difference between a mixed signal and a reference oscillator signal. A phase of the reference oscillator signal and/or a phase of the local oscillator signal are set for displacement and/or setting of the phase of the output signal, by analog or digital phase shifters. The phase shifters are used as frequency synthesizers. Independent claims are also included for the following: (1) a circuit configuration for phase shift or phase adjustment of an output signal produced by a tunable oscillator (2) an array antenna comprising a set of channels.

Description

The invention generally relates to a method and a circuit arrangement for phase shifting or phase adjustment of a signal generated by a controllable oscillator. In particular, the invention relates to a method and a circuit arrangement for the broadband phase shift or phase adjustment of a particular high-frequency signal generated by a voltage-controlled oscillator.

To adjust the phase of a high-frequency signal over a wide frequency range, it is firstly known to influence the signal directly at the (high) operating frequency with analog or digital phase shifters. On the other hand, it is known to initially move a low-frequency signal in phase analog or digital and then convert the phase-shifted signal to the desired higher operating frequency. This frequency conversion is usually carried out according to the overlay principle, d. H. by mixing the low-frequency signal with the signal of a local oscillator and subsequent filtering. This method is z. B. in known active array lamps ("phased array antenna") used, which are formed by a plurality of arranged in a matrix, individually controlled antenna elements.

Although analog and digital phase shifters are available in large numbers and for many frequency ranges, they can also be constructed in a compact and cost-effective manner. The disadvantage, however, is often that the bandwidth is relatively low.

A problem may also be that, especially with digital phase shifters, the accuracy, which is known to correspond to the digital increment plus a non-negligible tolerance deviation, is not sufficient. Although analogue phase shifters have no increment and can in principle be set very precisely, their phase is often not tunable over the entire phase range of 360 ° for the entire frequency range designed. Furthermore, high losses can occur in particular in the phase shift of high-frequency signals.

A disadvantage of the above-mentioned implementation of a low-frequency phase-shifted signal to a high frequency according to the overlay principle is also that due to the required filter (which are also quite expensive), the bandwidth is limited for this implementation. Finally, the required circuit complexity is relatively high.

The invention is therefore based on the object to provide a method and a circuit arrangement with which a phase shift or a phase adjustment of a particular high-frequency signal with high precision or fine division over a relatively large frequency range of the signal (i.e., broadband) is possible.

This object is achieved according to claim 1 with a method for phase shifting or phase adjustment of an output signal generated by a tunable oscillator, wherein the method is characterized in that the first frequency having an output signal of the oscillator mixed with a second frequency having local oscillator signal and the phase of Output signal of the oscillator in response to a phase difference between the mixed signal and a reference oscillator signal is controlled, wherein the phase of the reference oscillator signal and / or the phase of the local oscillator signal is set to shift or adjusting the phase of the output signal.

The object is further achieved according to claim 8 with a circuit arrangement in particular for carrying out a method according to claim 1, which is characterized in that a closed control loop with a mixer for mixing the first frequency having an output signal of the oscillator with a second frequency having local oscillator signal, and a phase detector for generating a control signal corresponding to a phase difference between the mixed signal and a reference oscillator signal for the oscillator.

Particular advantages of the inventive solutions compared to the two types of phase adjustment or displacement of a signal with or without subsequent frequency conversion according to the overlay principle described above are that the frequency bandwidth of the high-frequency phase-shifted signal is not limited in principle by the bandwidth of a phase shifter, but is determined by the tunability or controllability of the preferably voltage-controlled oscillator, as well as a reference signal generating reference oscillator and / or a local oscillator signal generating local oscillator.

Furthermore, the phase of the output signal can be set much more precisely and finely than is possible in the manner described above with known analog or digital phase shifters.

Also, the circuit complexity for the realization of the invention is much lower than in the frequency conversion after the Overlay principle, so that the inventive solution can be realized much cheaper.

Finally, there is also an advantage in that the phase shifting method according to the invention can in principle be used at any output signal frequency for which frequency generators in the form of PLL (phase-locked loop) synthesizers are available. Technological advances in the synthesizer components thus directly benefit the solution according to the invention and can be realized directly.

The dependent claims have advantageous developments of the method or the circuit arrangement to the content.

Further details, features and advantages of the invention will become apparent from the following description of exemplary and preferred embodiments of the invention with reference to the drawings. It shows:

1 a block diagram of a known frequency generator circuit;

2 a block diagram of a first embodiment of a circuit arrangement for phase adjustment according to the invention;

3 a block diagram of a second embodiment of a circuit arrangement for phase adjustment according to the invention;

4 a first application example of a circuit arrangement according to the invention in an active array antenna; and

5 a second example of application of a circuit arrangement according to the invention in an active array antenna.

For a better distinction from the offset synthesizer principle according to the invention is first based on the block diagram of the 1 the principle of operation of a known frequency generator (frequency multiplier) is explained according to the PLL synthesizer principle and then compared with the principle according to the invention.

Such a known frequency generator comprises according to 1 a phase detector 1 a free-running, voltage-controlled oscillator (VCO) is supplied with a first input which is supplied with a reference oscillator signal generated by a reference crystal oscillator Ref that is normally controlled by a reference Ref. 2 with an input connected to an output of the phase detector 1 is connected, and an output which is applied to an output A of the frequency generator. The frequency generator further comprises a frequency divider 3 with an input connected to the output of the voltage controlled oscillator 2 and an output connected to a second input of the phase detector 1 is applied.

The output signal of the voltage controlled oscillator 2 is by means of the frequency divider 3 divided down in frequency according to the set divider ratio. With the phase detector 1 becomes a phase difference between the output of the frequency divider 3 and the reference oscillator signal is determined and generates a phase difference corresponding control voltage with which the voltage controlled oscillator 2 is controlled.

This creates the well-known closed loop PLL, with the frequency of the output of the voltage controlled oscillator 2 applied output signal is multiplied according to the set divider ratio relative to the reference frequency of the reference oscillator signal, so that in the locked state, the two at the phase detector 1 applied signals have at least substantially the same frequency and the same phase. If the divider ratio is adjustable, the frequency of the output signal can be tuned accordingly.

When the phase of the phase detector 1 changed reference signal oscillator signal is changed, also changes the phase of the output signal of the voltage controlled oscillator 2 so that such a frequency synthesizer can also be used as a phase shifter.

A disadvantage of this method, however, is that the phase of the output signal compared to the phase of the reference oscillator signal to that in the divider 3 set divider ratio increases and therefore the accuracy of the phase adjustment of the output signal is also lower by this factor.

Known phase detectors can compare frequencies from about 100 MHz to a maximum of about 200 MHz. This means that for output signals of a few 10 GHz, divider ratios in the range of a few hundred are needed. If the output signal is to be adjustable in relatively small frequency steps, divider ratios of a few thousand or more are required.

In 2 Now, a schematic block diagram of a first embodiment of a circuit arrangement according to the invention is shown.

This circuit also has a phase detector 1 with a first input, which in turn is one with a customary one quartz-controlled reference oscillator Ref generated reference oscillator signal is supplied. On at the output of the phase detector 1 applied phase signal is used as a control signal to a control input of a tunable, usually voltage-controlled oscillator (VCO) 2 fed. An output of the oscillator 2 which is also connected to an output A of the circuit, is located at a first input of a mixer 31 at. A second input of the mixer 31 is with an output of a local oscillator 4 connected. An outlet of the mixer 31 is located at a second input of the phase detector 1 at.

With this circuit arrangement is thus in contrast to the in 1 shown circuit, a first frequency of the output signal of the tunable oscillator 2 (Oscillator signal) not by means of a divider 3 but with a second frequency of one through the local oscillator 4 generated local oscillator signal in the mixer 31 mixed so that (preferably after appropriate filtering) at the outlet of the mixer 31 a mixed signal (hereinafter referred to as mixer signal) is applied, whose frequency z. B. the difference frequency from the (first) frequency of the output signal of the oscillator 2 and represents the (second) frequency of the local oscillator signal.

In the phase detector 1 Then, the phase of the reference oscillator signal with the phase of the mixer signal (ie the output signal of the mixer 31 ) and comparing the phase difference representing phase signal in the form of a suitable control voltage for the tunable oscillator 2 generates, so that in turn a closed PLL loop is formed, with which the (first) frequency of the output signal of the oscillator 2 is preferably increased by the frequency of the mixer signal, ie the (first) frequency of the oscillator output signal is equal to the frequency of the reference oscillator signal plus or minus the frequency of the mixer signal.

In the steady state of the circuit, in turn, the phase and frequency difference of the two are the phase detector 1 supplied signals at least substantially zero, that is, the first frequency is mixed down with the second frequency to the reference frequency.

Since the mixing of two signals is an in-phase operation, a phase change of the reference oscillator signal results in an at least substantially identical phase change of the output signal of the tunable oscillator 2 and thus the output signal of the circuit arrangement at the output terminal A.

Also, a change in the phase of the local oscillator signal (and thus the phase of the mixer signal) leads to a corresponding phase change of the output signal of the tunable oscillator 2 ,

A change in the frequency of the output signal of the circuit arrangement can be achieved by changing the reference frequency of the reference oscillator Ref and / or the local oscillator frequency of the local oscillator 4 be made.

In this way, it is possible to precisely and finely adjust a desired high-frequency output in phase. The maximum frequency bandwidth of the output signal is determined by the tunability of the (voltage) controlled oscillator 2 and the tunability of the local oscillator 4 and / or the reference oscillator Ref determines.

3 shows a second embodiment of a circuit arrangement according to the invention. Same elements or components as in 2 are each provided with the same reference numerals, so that in this respect can be dispensed with a new explanation.

Unlike the in 2 embodiment shown, the circuit arrangement according to 3 a reference oscillator Ref for generating a reference oscillator signal whose frequency is adjustable, preferably manually or by another electronic assembly (not shown), thereby to determine the frequency of the output signal of the oscillator 2 (ie the output signal at the output A of the circuit) to change.

For shifting or adjusting the phase of the reference oscillator signal is a first analog or digital phase shifter, preferably manually or by another electronic module (not shown) 11 provided over which the reference oscillator signal phase-shifted the first input of the phase detector 1 is supplied, so that the phase of the output signal of the oscillator 2 (ie the output signal at the output A of the circuit arrangement) can be moved or adjusted accordingly.

Furthermore, the circuit according to 3 unlike the circuit according to 2 a second analog or digital phase shifter 41 on that between the local oscillator 4 and the mixer 31 is switched and with which the phase of the local oscillator signal manually or by another electronic module (not shown) can be set or changed, so as also the phase of the output signal of the controllable oscillator 2 (ie in turn the output signal at the output A of the circuit) to move or adjust.

The frequency of the local oscillator signal may also be adjustable for shifting or adjusting the frequency of the output signal of the circuit arrangement manually or by another electronic module (not shown).

Depending on the application and circuit design, it may be sufficient either only the first or only the second phase shifter 11 . 41 to provide in the circuit, and / or either only the reference oscillator Ref or only the local oscillator 4 adjustable in terms of its frequency.

In cases where the desired frequency of the output signal is so high that it is not directly connected to the voltage controlled oscillator 2 can be provided, a further mixer with local oscillator (and / or a frequency multiplier) may be provided, which is connected downstream of the output A of the circuit arrangement, to the frequency of the output signal of the oscillator 2 to implement the desired higher frequency. Preferably, however, a mixer with local oscillator is again used for this purpose so as not to impair the accuracy of the phase adjustment.

A preferred application of a phase shift circuit according to the invention can be found in the field of active, d. H. phased array antennas whose antenna characteristics are electronically panned.

Hereinafter, let it be assumed that a group antenna is constituted by a number n of individual emitters arranged in the form of a matrix for emitting or receiving electromagnetic signals, the matrix having a number z of rows Z1, ... Zz and a number s of columns S1, ... Ss and each row Zi has the number s of individual radiators A1, ... As and each column Sj the number z of individual radiators A1, ... Az, so that the total number n of the individual radiators is n = z × s yields.

The phases of the signals to be radiated or received via each individual emitter must be individually set or changed in each case by phase shifters in order to tilt the antenna characteristic.

A first application example of a circuit arrangement according to the invention is shown in the schematic block diagram in FIG 4 It has been assumed that each individual emitter A1, A2, .... is part of a respective channel K which, in addition to the individual emitter, has the electrical components individually required for its control. The array antenna thus has a number n of channels K1, K2, ... Kn, and each channel comprises the in 4 for a first channel K1 shown components, the other channels K2, ... Kn are indicated only schematically.

Same or corresponding components as in 3 are in 4 again denoted by the same reference numerals, so that can be waived in this respect to a new explanation.

4 thus shows a circuit arrangement according to the invention 3 whose output A is connected to a first input of a mixer M1. A second input of the mixer M1 is connected to a source DS for a payload or data signal. With the mixer M1 is applied to its first input output of the controlled oscillator 2 mixed with the useful or data signal and fed via an output terminal of the mixer M1 as a transmission signal to a first individual radiator A1 of the array antenna for radiation.

The further channels K2, .... Kn are indicated only schematically and constructed in the same way as the first channel K1. As further indicated, the source DS is connected to the mixers M1, M2, ... Mn of each channel K1, K2, ... Kn.

Since, as is known, all individual radiators A1, A2,... Have to be actuated on a group antenna with coherent transmission signals, a common reference oscillator Ref and a common local oscillator are present for all channels K1, K2,... Kn of the group antenna 4 provided, of which preferably at least one is adjustable in its frequency.

In this case, the reference oscillator Ref is with every first phase shifter 11 each channel K1, K2, ... Kn and the local oscillator 4 with every second phase shifter 41 each channel K1, K2, ... Kn connected.

Thus, therefore, the phase of each individual radiator A1, A2, ... An radiated signal in each channel K1, K2, ... Kn individually by means of in 3 shown circuit arrangement, which is used here as a phase shifter circuit can be adjusted by, as described above, the first and / or the second phase shifter 11 ; 41 by means of further electronic modules (not shown) is driven accordingly.

The data or useful signal to be radiated is converted in the mixers M1, M2,... Mn to the transmission frequency by means of the output signal of the phase shifter circuit serving as a local oscillator signal and then emitted via the individual radiators A1, A2,...

A second application example of a circuit arrangement according to the invention relates to in the DE 10 2007 062 079 described group antenna, of which essential components in the block diagram of 5 are indicated schematically. Same or corresponding components as in the 3 and 4 are in the 5 again denoted by the same reference numerals, so that can be waived in this respect to a new explanation.

Unlike the in 4 shown in the first application example is in the second application example according to 5 not every channel K1, K2, ... Kn of the array antenna individually, but each row Z1, ... Zz of individual radiators A1, ... As and each column S1, ... Ss of individual radiators A1, ... Az respectively triggered by a common circuit arrangement according to the invention.

Thus, according to 5 the output A of a circuit according to 3 with all channels K1, K2, ... Ks of a first row Z1 of individual radiators A1,... As of the matrix arrangement, ie the respective first input of all mixers M1, M2, ... Ms of the first row Z1. The same applies to all other circuit arrangements and all other lines Z2, ... Zz (again indicated only schematically) and for all columns S1, ... Ss (not shown) of the matrix arrangement of individual radiators A1, ... An.

The second input of all mixers M1, M2, ... Mn of the array antenna (i.e., all rows and columns) is connected to a common source DS for a payload or data signal.

To ensure the coherence of the transmission of all individual emitters A1, ... At the group antenna transmission signals is again for channels K1, .... Kn, ie for all rows and all columns, a common reference oscillator Ref and a common local oscillator 4 provided, of which in turn preferably at least one is adjustable in its frequency.

This second application example has the advantage that in the case of a group antenna with a number n = z × s of individual radiators or channels, only a number m of (z + s) circuit arrangements according to the invention is required (see DE 10 2007 062 079 ), while in the first application example according to 4 a number n of (z × s) circuit arrangements according to the invention is required.

In other words, therefore, in the second application example, all the individual radiators of a row Zi are driven with the same phase-shifted signal. The same applies to the individual radiators of a column Sj. The directional adjustment of the array antenna is effected in that each individual radiator A is controlled via the line Zi and the column Sj at whose intersection point in the matrix arrangement the relevant individual radiator A is located. The phase emitted by a single radiator A then results from the sum of the phases supplied via the relevant row Zi and the relevant column Sj.

Here again, as explained above, the first and / or the second phase shifter 11 ; 41 the respective row Zi and the respective column Sj by means of further electronic modules (not shown) so controlled that the respective individual radiator A with the desired (summed) phase position emits signals.

The data or useful signal to be radiated is in turn converted to the transmission frequency in the mixers M1, M2,... Mn by means of the output signals serving as local oscillator signal at the output A of the circuit arrangements according to the invention and then emitted via the individual radiators A1, A2,...

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007062079 [0054, 0059]

Claims (16)

A method for phase shifting or phase adjustment of an output signal generated by a variable frequency oscillator, characterized in that the first frequency having an output signal of the oscillator mixed with a second frequency having local oscillator signal and the phase of the output signal of the oscillator in response to a phase difference between the mixed signal and a reference oscillator signal is controlled, wherein the phase of the reference oscillator signal and / or the phase of the local oscillator signal is set to shift or adjusting the phase of the output signal. The method of claim 1, wherein the first frequency is equal to the frequency of the reference oscillator signal plus or minus the frequency of the mixed signal. The method of claim 1, wherein the frequency of the mixed signal is a difference frequency between the first frequency and the second frequency. The method of claim 1, wherein the first frequency is set by adjusting the frequency of the reference oscillator signal and / or by adjusting the second frequency. Method according to Claim 1, in which the adjustment of the phase of the reference oscillator signal by means of a first analog or digital phase shifter ( 11 ) is made. Method according to Claim 1, in which the adjustment of the phase of the local oscillator signal by means of a second analog or digital phase shifter ( 41 ) is made. The method of claim 1, wherein the first frequency is converted by means of another mixer and a further local oscillator and / or a frequency multiplier to a desired higher output frequency. Circuit arrangement for phase shifting or phase adjustment of a tunable oscillator ( 2 ), in particular for carrying out a method according to claim 1, characterized by a closed control loop with a mixer ( 31 ) for mixing the first frequency output signal of the oscillator ( 2 ) having a second frequency having local oscillator signal, and a phase detector ( 1 ) for generating a control signal corresponding to a phase difference between the mixed signal and a reference oscillator signal for the oscillator ( 2 ). Circuit arrangement according to Claim 8, having a first analog or digital phase shifter ( 11 ) for shifting or adjusting the phase of the reference oscillator signal. Circuit arrangement according to Claim 8, with a second analog or digital phase shifter ( 41 ) for shifting or adjusting the phase of the local oscillator signal. Circuit arrangement according to Claim 8, having a reference oscillator (Ref) for generating the reference oscillator signal. Circuit arrangement according to claim 11, wherein the frequency of the reference oscillator signal is adjustable. Circuit arrangement according to Claim 8, having a local oscillator ( 4 ) for generating the local oscillator signal. Circuit arrangement according to claim 13, wherein the frequency of the local oscillator signal is adjustable. Circuit arrangement according to Claim 8, in which the tunable oscillator ( 2 ) is a voltage controlled oscillator. Group antenna having a plurality of channels (K1, K2, ... Kn) each having a single radiator (A1, A2, ... An) and a circuit arrangement according to claim 8 for generating and shifting the phase of at least one of the individual radiators (A1 , A2, ... An) to be radiated signal.

Images