CA2021749A1 - Bi-phase code generation and amplification circuit for microwave and millimeter-wave frequencies - Google Patents
Bi-phase code generation and amplification circuit for microwave and millimeter-wave frequenciesInfo
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- CA2021749A1 CA2021749A1 CA 2021749 CA2021749A CA2021749A1 CA 2021749 A1 CA2021749 A1 CA 2021749A1 CA 2021749 CA2021749 CA 2021749 CA 2021749 A CA2021749 A CA 2021749A CA 2021749 A1 CA2021749 A1 CA 2021749A1
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- frequency
- vco
- phase
- controlled oscillator
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Abstract
ABSTRACT OF THE DISCLOSURE
A system for bi-phase code generation with signal amplification is disclosed in which a digital signal applied to the tuning voltage input of an injection locked voltage controlled oscillator (VCO) is used to produce a corresponding phase modulated output signal at the locked frequency of the VCO. The invention includes a voltage controlled oscillator (VCO) 12, a tuning voltage source 14, a three-port circulator 20, and a locking frequency source 28. The output signal from the VCO 18 is applied to a second input port of the three-port circulator 22, while a locking frequency signal is applied to a first input port of the three-port circulator 24. This arrangement causes the frequency of the output signal produced by the VCO 18 to be locked to the frequency of the signal injected into the first port of the three-port circulator. As the output frequency of the VCO 18 is locked to the frequency of the injected signal, a change in the tuning voltage applied to the VCO
16 results in a corresponding change in the phase of the output signal produced by the VCO 18, instead of a change in frequency. This allows the final output signal of the injection locked VCO 18 to be phase modulated in accordance with the applied tuning voltages.
Furthermore, the injected signal is amplified by the associated gain produced by the VCO. Consequently, both signal amplification and continuous phase adjustability is achieved with this invention.
A system for bi-phase code generation with signal amplification is disclosed in which a digital signal applied to the tuning voltage input of an injection locked voltage controlled oscillator (VCO) is used to produce a corresponding phase modulated output signal at the locked frequency of the VCO. The invention includes a voltage controlled oscillator (VCO) 12, a tuning voltage source 14, a three-port circulator 20, and a locking frequency source 28. The output signal from the VCO 18 is applied to a second input port of the three-port circulator 22, while a locking frequency signal is applied to a first input port of the three-port circulator 24. This arrangement causes the frequency of the output signal produced by the VCO 18 to be locked to the frequency of the signal injected into the first port of the three-port circulator. As the output frequency of the VCO 18 is locked to the frequency of the injected signal, a change in the tuning voltage applied to the VCO
16 results in a corresponding change in the phase of the output signal produced by the VCO 18, instead of a change in frequency. This allows the final output signal of the injection locked VCO 18 to be phase modulated in accordance with the applied tuning voltages.
Furthermore, the injected signal is amplified by the associated gain produced by the VCO. Consequently, both signal amplification and continuous phase adjustability is achieved with this invention.
Description
20217~ -A BI-PHASE CODE GENERATION AND AMPLIFICATION CIRCUIT
FOR MICROWAVE AND MILLINETER-WAVE FREQUENCIBS
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BACR~ROUND OF THE INVENTION
;'.' ' '''" ' ' ''.'. ,' .":- '-' Field of the Invention: `
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The present invention relates to electronic circuits - -used for bi-phase code generation. More specifically, the present invention relates to injection locked voltage controlled oscillator (VCO) circuits used for bi-phase ~ ~ `
code generation with signal amplification.
While the present invention is described herein with `
reference to an illustrative embodiment for a particular ~-application, it is understood that the invention is not limited thereto. Those having ordinary skill in the art 15 and access to the teachings provided herein will recog- ~ ~
nize additional modifications, applications and embodi- ~ -ments within the scope of the present invention.
pescription of the Related Art:
Bi-phase code generation is a method for encoding digital information onto a constant frequency signal by~
phase modulating the signal between two distinct phase states. One phase state of the signal is used to 25 represent a digital '1', while the other phase state is -~
;used to represent a digital '0'. Using this method, digital information can be transmitted by a signal -`~
operating at a single frequency.
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-- 202~
, Bi-phase coded microwave and millimeter-wave signals are widely used in high resolution radar and spread spectrum applications. Conventional systems of these types which require bi-phase coding typically encode digital data onto an intermediate frequency (I.F.) signal using a PIN diode modulator. The resulting bi-phase coded I.F. signal must then be amplified. Upconversion to the final output frequency is performed with a mixer circuit using a second I.F. signal with a frequency located in the range of the final output frequency. The upconverted bi-phase coded signal output by the mixer circuit must then be filtered by a suitable bandpass filter to remove spurious frequency components generated by the mixing process. The resulting signal is again amplified to achieve the final output signal level.
This conventional method of bi-phase code generation for microwave and millimeter-wave signals has three shortcomings. One problem is the large amount of circuitry required to implement the modulation, mixing, filtering and amplification stages used in this type of design. A second problem is due to a reduction in the signal to noise ratio of the final output signal caused by conversion losses and electrical noise added by each of the various stages used to process the signal. And third, since the modulation process attenuates the signal, many amplifiers are required to achieve an appropriate signal level.
Although not specifically designed for bi-phase code generation, a simplified system for providing phase modulated output from a synchronized oscillator chain has been described by Helmut Barth, "A 94 GHz Synchronized Oscillator Chain for Fast, Continuous 360 Degree Phase Modulation," IEEE MTT-S Digest, 1987. This system uses two second harmonic mode oscillators having output ports for their fundamental and second harmonic waves. The ' .- : ' .: -. : - .,: . . . .
FOR MICROWAVE AND MILLINETER-WAVE FREQUENCIBS
., ~ ~ `, ., ! . .
BACR~ROUND OF THE INVENTION
;'.' ' '''" ' ' ''.'. ,' .":- '-' Field of the Invention: `
~`
The present invention relates to electronic circuits - -used for bi-phase code generation. More specifically, the present invention relates to injection locked voltage controlled oscillator (VCO) circuits used for bi-phase ~ ~ `
code generation with signal amplification.
While the present invention is described herein with `
reference to an illustrative embodiment for a particular ~-application, it is understood that the invention is not limited thereto. Those having ordinary skill in the art 15 and access to the teachings provided herein will recog- ~ ~
nize additional modifications, applications and embodi- ~ -ments within the scope of the present invention.
pescription of the Related Art:
Bi-phase code generation is a method for encoding digital information onto a constant frequency signal by~
phase modulating the signal between two distinct phase states. One phase state of the signal is used to 25 represent a digital '1', while the other phase state is -~
;used to represent a digital '0'. Using this method, digital information can be transmitted by a signal -`~
operating at a single frequency.
~. ~
- ::
' :~: -,. ~-: .
' ' - .
' ''" '.
-- 202~
, Bi-phase coded microwave and millimeter-wave signals are widely used in high resolution radar and spread spectrum applications. Conventional systems of these types which require bi-phase coding typically encode digital data onto an intermediate frequency (I.F.) signal using a PIN diode modulator. The resulting bi-phase coded I.F. signal must then be amplified. Upconversion to the final output frequency is performed with a mixer circuit using a second I.F. signal with a frequency located in the range of the final output frequency. The upconverted bi-phase coded signal output by the mixer circuit must then be filtered by a suitable bandpass filter to remove spurious frequency components generated by the mixing process. The resulting signal is again amplified to achieve the final output signal level.
This conventional method of bi-phase code generation for microwave and millimeter-wave signals has three shortcomings. One problem is the large amount of circuitry required to implement the modulation, mixing, filtering and amplification stages used in this type of design. A second problem is due to a reduction in the signal to noise ratio of the final output signal caused by conversion losses and electrical noise added by each of the various stages used to process the signal. And third, since the modulation process attenuates the signal, many amplifiers are required to achieve an appropriate signal level.
Although not specifically designed for bi-phase code generation, a simplified system for providing phase modulated output from a synchronized oscillator chain has been described by Helmut Barth, "A 94 GHz Synchronized Oscillator Chain for Fast, Continuous 360 Degree Phase Modulation," IEEE MTT-S Digest, 1987. This system uses two second harmonic mode oscillators having output ports for their fundamental and second harmonic waves. The ' .- : ' .: -. : - .,: . . . .
2 0 2 1 7 4~
fundamental output ports of the two oscillators are connected by a waveguide which allows one of the oscillators (a varactor tuned slave oscillator) to be locked at its fundamental frequency by a fixed, tuned master oscillator. The phase difference between the second harmonic outputs of each of the oscillators can then be controlled by changing the tuning voltage applied to the varactor of the slave oscillator.
Although this system represents an improvement over prior phase modulation systems, it also suffers from three significant limitations. The first limitation is that the system only provides phase modulated output signals of the second harmonic frequency of the oscillator chain. The second limitation is that the power levels of the second harmonic signals output by the system are substantially less than the power levels of the fundamental frequency signals produced by the oscillator chain, resulting in a net loss of output signal power. The third limitation is that the construction and tuning of the waveguide connecting the two oscillators is critical to the operation of the system, making fabrication of the system a difficult task.
Accordingly, there is a need in the art for a simple bi-phase code generation system fabricated from readily available components which can directly phase modulate and amplify microwave or millimeter wave signals without the use of intermediate frequencies.
-SUMMARY OF THE INVENTION
The need in the art is addressed by the present invention which provides a bi-phase code generation system with gain for microwave and millimeter-wave signals.
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The invention includes a voltage controlled oscillator (VCO), a tuning voltage source, and injection locking circuitry for injection locking the voltage controlled oscillator to the frequency of an injected -signal. In a specific embodiment, the injection locking circuitry includes a three port circulator, and a locking frequency source. A locking frequency reference signal is applied to the first port of the three port circulator ;~
and the output of the VCO is connected to the second port of the circulator. The power level of the reference signal is significantly less than the power of the signal ~ ~ ;
generated by the VCO. Since the circulator allows propagation of radio frequency energy in one direction only, this arrangement causes the signal output by the VCO to be locked to the frequency of the reference signal. Thus, the resulting signal output from port 3 of the circulator possesses both the frequency stability of the reference signal and the amplified power level of the ~ ;~
VCO signal. As the frequency of the signal output by the ~;
VCo is locked to the frequency of the reference signal, a change in the tuning voltage applied to the VCO produces a change in the phase of the output signal. This allows the final output signal of the injection locked VCO to be ~-~
phase modulated in accordance with the tuning voltage applied to the VCO. Therefore, instead of a loss in the signal power of the reference frequency, as encountered in conventional systems, the final phase modulated signal -output from port 3 of the circulator exhibits a net gain in power provided by the VCO. ~ ~
~ -;
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l(a) is a block diagram of the present invention.
35 Figure l(b) is a graph illustrating the . . ` :
2 ~ 2 1 7 9! ~
: 5 , ~:
relationship between the locking signal and the signal output by the injection locked voltage controlled oscillator (VCO) with an applied tuning voltage VT1. :~
Figure l(c) is a graph illustrating the relationship between the locking signal and the signal output by the injection locked VCO with an applied tuning voltage VT2.
Figure 2 is a simplified block diagram of a conventional (non-injection locked) VCO. : - :.:
Figure 3 is a graph illustrating the frequency .
10 response of an injection locked VCO operated with two : .~:~
different tuning voltages.
Figure 4 is a block diagram of an alternative ..
embodiment of the present invention using an amplifier with an electrically tunable impedance matching network 15 in place of a VCO. ~ ~;
, DESCRIP~ION OF THE INVENTION
Figure l(a) shows a block diagram of the bi-phase .
20 code generation system of the present invention. The ~::.:
bi-phase code generation system 10 includes a voltage :~
controlled oscillator (VCO) 12, a tuning voltage source 14, a three-port circulator 20, and a locking frequency reference source 28. :
The output of the VCO 18 is connected to a second -~
input port 22 of the three-port circulator 20. The three ;~
port circulator is a standard type of ferromagnetic device which is readily available from companies such as Microwave Associates (LOCATION). The locking frequency : ~ .
reference source 28 injects a locking frequency signal (F
LOCK/IN 23) into a first input port 24 of the three-port ~-.. :-circulator 20. The low power locking frequency signal (F
LOCK/IN 23) injected into the second input port 24 of the circulator 20 modulates the active impedance of the VCO's -~
active microwave device in.a manner which effectively ;,.'-,'','.,:
' ' `"~``" ' ' ' . ' ' ' 2021 7~
locks the output frequency of the VCO (FLOCK/OUT 21) to the locking signal frequency (FlOCK/IN 23).
As shown in Figure l(b), this technique allows the VCo's output signal FLOCK/OUT(~1) 30 to be locked to the frequency of the locking reference signal F lock/In 32.
The phase difference between the two signals is a function of the tuning voltage applied to the VCO, and will be discussed in more detail below. Since the injection locking process allows the lower power locking reference signal FLOCK/IN 32 to control the higher power output signal of the VCO (FLOCK/OUT 30), this arrangement offers the added benefit of producing a net gain in power. The previously described technique of locking the output frequency of a VCO to the frequency of an injected signal is known in the art as "injection locking".
Figure 2 shows a block diagram of a conventional VCO
system 40, including a voltage controlled oscillator (VCO) 46, and a tuning voltage source 42 connected to the tuning voltage input 44 of the VCO 46. One skilled in the art will recognize that the conventional VCO system shown in Figure 2 will respond to a change in the tuning voltage applied to the VCO (VTl,VT2) with a corresponding change in the FREQUENCY of the signal output by the VCO
(FVCO1, FVCO2). In contrast, the injection locked VCO of the present invention responds to a change in the tuning voltage applied to the VCO with a corresponding change in the PHASE of the signal output by the VCO. This is due to the fact that once the VCO is injection locked to a reference frequency, its operating frequency can no longer change in response to a change in applied tuning voltage. Instead, a change in the applied tuning voltage results in a corresponding change in the phase of the signal output by the VCO. As shown in Figures l(b) and l(c), an injection locked VCO responds to a change in the applied tuning voltage (from VTl to VT2) with a , :, : . ,, . ...................................... . . :-;. -. ~ . .. .
~ r ~ , . ' ' : ' ' ' ' 2 0 2 1 7 ~
corresponding change in the phase of the signal output by the VCO (from ~1 to ~2) In order for the system of the present invention to act as a bi-phase code generator, the tuning voltages VTl and VT2 selected must cause the VCO to produce output signals which are 180 degrees out of phase. A digital signal consisting of levels VTl and VT2 applied to the VC0 will then produce a bi-phase coded output signal from the VCO. Alternatively, if the voltage levels of the digital signal do not correspond to the requisite VTl and VT2 voltage levels, the digital signal can be applied to a Digital to Analog (D/A) converter which will generate the VTl and VT2 voltage levels required to achieve a 180 degree phase change in the signal output from the VCO.
A final consideration in the implementation of the present invention is the selection ofOthe locking frequency. In the injection locked oscillator, if the frequency of the locking reference signal is varied, the oscillator will remain locked to this signal provided the signal frequency does not vary outside the locking bandwidth of the oscillator. This locking bandwidth is a function of the tuning voltage applied to the oscillator and the power of the locking reference signal. In general, the higher the power of the locking reference signal, the wider the locking bandwidth of the oscillator. Locking reference signals with frequencies outside the locking bandwidth of the oscillator will be ignored by the oscillator, which will continue to operate at its own fundamental frequency of oscillation.
Therefore, as shown in Figure 3, the frequency of the locking reference signal must be selected so that it falls within the locking bandwidth of the oscillator when operated at the tuning voltages V1 and V2. LBW(V1) 58 is the locking bandwidth of the VC0 when operated with an applied tuning voltage V1. Similarly, LBW(V2) 60 is the `''"''`` `, ;' ~ ~
. ' ~..
2 0 2 1 ~
locking bandwidth of the VCO when operated with an applied tuning voltage V2. The tuning voltages Vl and V2 are selected so that the resulting locking bandwidths LBW(V1) 58 and LBW(V2) 60 overlap, as shown in Figure 3.
A single locking reference frequency FLOCK/IN 56 is then chosen from the range of locking frequencies common to both LBW(V1) 58 and LBW(V2) 60 . This arrangement allows the selected locking reference signal FLOCK/IN 56 to injection lock the output frequency of the VCO operated with an applied tuning voltage of either V1 or V2. Under these conditions, since the output frequency of the VCO
is locked to the reference signal frequency, a change in the tuning voltage applied to the VCO (from V1 to V2) will result in a shift in the phase of the output signal of the VCO. Depending on the selection of Vl and V2, the signal phase may be made to vary continuously through greater than 180 degree of phase shift. Furthermore, the signal is amplified as a result of the associated gain of the VCO.
An alternative embodiment of the present invention which uses an amplifier having electrically tunable impedance matching network in place of the VCO is shown in Figure 4. In this embodiment, a reference signal source 72 provides a reference signal FLOCK 76A which is input to an amplifier 78 having an electrically tunable impedance matching network. The impedance of the amplifier 78 is controlled by the tuning voltage applied to the impedance control circuit 80. A change in the impedance of the amplifier 78 produces a corresponding change in the phase of the amplified reference signal FLOCK (~ 2) 76B output from the amplifier 78. Bi-phase code generation is accomplished by applying a data input signal DIN 82A to a digital to analog converter 84 from a data input source 70. The resulting data output signal DOUT 82B is then applied to the impedance control ' '. '' .' . ~ `~- :.
, : - . .... , ~ ., : .
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2~217~3 g circuit 80. Since this signal consists of two states -(high and low~, the impedance of the amplifier 78 is -~
forced into two different corresponding states. In this way, a digital input signal DIN 82A can be used to control the phase of the final output signal, FLOCK (~
~2) 76B produced by the system of the present invention. ~ -~
The present invention has been described herein with -reference to a particular embodiment for a particular `
application. Nonetheless, the invention is not limited thereto. For example, it will be apparent to those of - ordinary skill in the art that the phase shift in the -~
output signal of the present invention is not limited to just two phases, but is continuously variable over a wide range. Another obvious modification of the present 15 invention would be to cascade two VCO units which would -~
provide additional gain and greater than 360 degrees of phase adjustment. It should be noted that the system of `
the present invention is not limited to the production of ~i a signal with only two phase values but is capable of producing a signal of continuously variable phase, since the phase of the output signal is a function of the tuning voltage applied to the VCO of the system.
Those of ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof. It is intended by the appended claims to cover any and all such modifications, applications, and embodiments within the scope of the invention.
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fundamental output ports of the two oscillators are connected by a waveguide which allows one of the oscillators (a varactor tuned slave oscillator) to be locked at its fundamental frequency by a fixed, tuned master oscillator. The phase difference between the second harmonic outputs of each of the oscillators can then be controlled by changing the tuning voltage applied to the varactor of the slave oscillator.
Although this system represents an improvement over prior phase modulation systems, it also suffers from three significant limitations. The first limitation is that the system only provides phase modulated output signals of the second harmonic frequency of the oscillator chain. The second limitation is that the power levels of the second harmonic signals output by the system are substantially less than the power levels of the fundamental frequency signals produced by the oscillator chain, resulting in a net loss of output signal power. The third limitation is that the construction and tuning of the waveguide connecting the two oscillators is critical to the operation of the system, making fabrication of the system a difficult task.
Accordingly, there is a need in the art for a simple bi-phase code generation system fabricated from readily available components which can directly phase modulate and amplify microwave or millimeter wave signals without the use of intermediate frequencies.
-SUMMARY OF THE INVENTION
The need in the art is addressed by the present invention which provides a bi-phase code generation system with gain for microwave and millimeter-wave signals.
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The invention includes a voltage controlled oscillator (VCO), a tuning voltage source, and injection locking circuitry for injection locking the voltage controlled oscillator to the frequency of an injected -signal. In a specific embodiment, the injection locking circuitry includes a three port circulator, and a locking frequency source. A locking frequency reference signal is applied to the first port of the three port circulator ;~
and the output of the VCO is connected to the second port of the circulator. The power level of the reference signal is significantly less than the power of the signal ~ ~ ;
generated by the VCO. Since the circulator allows propagation of radio frequency energy in one direction only, this arrangement causes the signal output by the VCO to be locked to the frequency of the reference signal. Thus, the resulting signal output from port 3 of the circulator possesses both the frequency stability of the reference signal and the amplified power level of the ~ ;~
VCO signal. As the frequency of the signal output by the ~;
VCo is locked to the frequency of the reference signal, a change in the tuning voltage applied to the VCO produces a change in the phase of the output signal. This allows the final output signal of the injection locked VCO to be ~-~
phase modulated in accordance with the tuning voltage applied to the VCO. Therefore, instead of a loss in the signal power of the reference frequency, as encountered in conventional systems, the final phase modulated signal -output from port 3 of the circulator exhibits a net gain in power provided by the VCO. ~ ~
~ -;
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l(a) is a block diagram of the present invention.
35 Figure l(b) is a graph illustrating the . . ` :
2 ~ 2 1 7 9! ~
: 5 , ~:
relationship between the locking signal and the signal output by the injection locked voltage controlled oscillator (VCO) with an applied tuning voltage VT1. :~
Figure l(c) is a graph illustrating the relationship between the locking signal and the signal output by the injection locked VCO with an applied tuning voltage VT2.
Figure 2 is a simplified block diagram of a conventional (non-injection locked) VCO. : - :.:
Figure 3 is a graph illustrating the frequency .
10 response of an injection locked VCO operated with two : .~:~
different tuning voltages.
Figure 4 is a block diagram of an alternative ..
embodiment of the present invention using an amplifier with an electrically tunable impedance matching network 15 in place of a VCO. ~ ~;
, DESCRIP~ION OF THE INVENTION
Figure l(a) shows a block diagram of the bi-phase .
20 code generation system of the present invention. The ~::.:
bi-phase code generation system 10 includes a voltage :~
controlled oscillator (VCO) 12, a tuning voltage source 14, a three-port circulator 20, and a locking frequency reference source 28. :
The output of the VCO 18 is connected to a second -~
input port 22 of the three-port circulator 20. The three ;~
port circulator is a standard type of ferromagnetic device which is readily available from companies such as Microwave Associates (LOCATION). The locking frequency : ~ .
reference source 28 injects a locking frequency signal (F
LOCK/IN 23) into a first input port 24 of the three-port ~-.. :-circulator 20. The low power locking frequency signal (F
LOCK/IN 23) injected into the second input port 24 of the circulator 20 modulates the active impedance of the VCO's -~
active microwave device in.a manner which effectively ;,.'-,'','.,:
' ' `"~``" ' ' ' . ' ' ' 2021 7~
locks the output frequency of the VCO (FLOCK/OUT 21) to the locking signal frequency (FlOCK/IN 23).
As shown in Figure l(b), this technique allows the VCo's output signal FLOCK/OUT(~1) 30 to be locked to the frequency of the locking reference signal F lock/In 32.
The phase difference between the two signals is a function of the tuning voltage applied to the VCO, and will be discussed in more detail below. Since the injection locking process allows the lower power locking reference signal FLOCK/IN 32 to control the higher power output signal of the VCO (FLOCK/OUT 30), this arrangement offers the added benefit of producing a net gain in power. The previously described technique of locking the output frequency of a VCO to the frequency of an injected signal is known in the art as "injection locking".
Figure 2 shows a block diagram of a conventional VCO
system 40, including a voltage controlled oscillator (VCO) 46, and a tuning voltage source 42 connected to the tuning voltage input 44 of the VCO 46. One skilled in the art will recognize that the conventional VCO system shown in Figure 2 will respond to a change in the tuning voltage applied to the VCO (VTl,VT2) with a corresponding change in the FREQUENCY of the signal output by the VCO
(FVCO1, FVCO2). In contrast, the injection locked VCO of the present invention responds to a change in the tuning voltage applied to the VCO with a corresponding change in the PHASE of the signal output by the VCO. This is due to the fact that once the VCO is injection locked to a reference frequency, its operating frequency can no longer change in response to a change in applied tuning voltage. Instead, a change in the applied tuning voltage results in a corresponding change in the phase of the signal output by the VCO. As shown in Figures l(b) and l(c), an injection locked VCO responds to a change in the applied tuning voltage (from VTl to VT2) with a , :, : . ,, . ...................................... . . :-;. -. ~ . .. .
~ r ~ , . ' ' : ' ' ' ' 2 0 2 1 7 ~
corresponding change in the phase of the signal output by the VCO (from ~1 to ~2) In order for the system of the present invention to act as a bi-phase code generator, the tuning voltages VTl and VT2 selected must cause the VCO to produce output signals which are 180 degrees out of phase. A digital signal consisting of levels VTl and VT2 applied to the VC0 will then produce a bi-phase coded output signal from the VCO. Alternatively, if the voltage levels of the digital signal do not correspond to the requisite VTl and VT2 voltage levels, the digital signal can be applied to a Digital to Analog (D/A) converter which will generate the VTl and VT2 voltage levels required to achieve a 180 degree phase change in the signal output from the VCO.
A final consideration in the implementation of the present invention is the selection ofOthe locking frequency. In the injection locked oscillator, if the frequency of the locking reference signal is varied, the oscillator will remain locked to this signal provided the signal frequency does not vary outside the locking bandwidth of the oscillator. This locking bandwidth is a function of the tuning voltage applied to the oscillator and the power of the locking reference signal. In general, the higher the power of the locking reference signal, the wider the locking bandwidth of the oscillator. Locking reference signals with frequencies outside the locking bandwidth of the oscillator will be ignored by the oscillator, which will continue to operate at its own fundamental frequency of oscillation.
Therefore, as shown in Figure 3, the frequency of the locking reference signal must be selected so that it falls within the locking bandwidth of the oscillator when operated at the tuning voltages V1 and V2. LBW(V1) 58 is the locking bandwidth of the VC0 when operated with an applied tuning voltage V1. Similarly, LBW(V2) 60 is the `''"''`` `, ;' ~ ~
. ' ~..
2 0 2 1 ~
locking bandwidth of the VCO when operated with an applied tuning voltage V2. The tuning voltages Vl and V2 are selected so that the resulting locking bandwidths LBW(V1) 58 and LBW(V2) 60 overlap, as shown in Figure 3.
A single locking reference frequency FLOCK/IN 56 is then chosen from the range of locking frequencies common to both LBW(V1) 58 and LBW(V2) 60 . This arrangement allows the selected locking reference signal FLOCK/IN 56 to injection lock the output frequency of the VCO operated with an applied tuning voltage of either V1 or V2. Under these conditions, since the output frequency of the VCO
is locked to the reference signal frequency, a change in the tuning voltage applied to the VCO (from V1 to V2) will result in a shift in the phase of the output signal of the VCO. Depending on the selection of Vl and V2, the signal phase may be made to vary continuously through greater than 180 degree of phase shift. Furthermore, the signal is amplified as a result of the associated gain of the VCO.
An alternative embodiment of the present invention which uses an amplifier having electrically tunable impedance matching network in place of the VCO is shown in Figure 4. In this embodiment, a reference signal source 72 provides a reference signal FLOCK 76A which is input to an amplifier 78 having an electrically tunable impedance matching network. The impedance of the amplifier 78 is controlled by the tuning voltage applied to the impedance control circuit 80. A change in the impedance of the amplifier 78 produces a corresponding change in the phase of the amplified reference signal FLOCK (~ 2) 76B output from the amplifier 78. Bi-phase code generation is accomplished by applying a data input signal DIN 82A to a digital to analog converter 84 from a data input source 70. The resulting data output signal DOUT 82B is then applied to the impedance control ' '. '' .' . ~ `~- :.
, : - . .... , ~ ., : .
, ."
2~217~3 g circuit 80. Since this signal consists of two states -(high and low~, the impedance of the amplifier 78 is -~
forced into two different corresponding states. In this way, a digital input signal DIN 82A can be used to control the phase of the final output signal, FLOCK (~
~2) 76B produced by the system of the present invention. ~ -~
The present invention has been described herein with -reference to a particular embodiment for a particular `
application. Nonetheless, the invention is not limited thereto. For example, it will be apparent to those of - ordinary skill in the art that the phase shift in the -~
output signal of the present invention is not limited to just two phases, but is continuously variable over a wide range. Another obvious modification of the present 15 invention would be to cascade two VCO units which would -~
provide additional gain and greater than 360 degrees of phase adjustment. It should be noted that the system of `
the present invention is not limited to the production of ~i a signal with only two phase values but is capable of producing a signal of continuously variable phase, since the phase of the output signal is a function of the tuning voltage applied to the VCO of the system.
Those of ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof. It is intended by the appended claims to cover any and all such modifications, applications, and embodiments within the scope of the invention.
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Claims (6)
1. A system for producing a bi-phase coded output signal comprising:
a voltage controlled oscillator;
means for injection locking said voltage controlled oscillator to the frequency of an injected signal; and means for applying tuning voltages to said voltage controlled oscillator to cause the phase of the fundamental frequency output signal from said voltage controlled oscillator to vary as a function of the applied tuning voltage and to be amplified by the associated gain of the voltage controlled oscillator.
a voltage controlled oscillator;
means for injection locking said voltage controlled oscillator to the frequency of an injected signal; and means for applying tuning voltages to said voltage controlled oscillator to cause the phase of the fundamental frequency output signal from said voltage controlled oscillator to vary as a function of the applied tuning voltage and to be amplified by the associated gain of the voltage controlled oscillator.
2. The system of claim 1 wherein said means for injection locking said voltage controlled oscillator comprises a locking frequency source and a three port circulator.
3. The system of claim 2 wherein said means for applying tuning voltages to said voltage controlled oscillator includes means for applying first and second tuning voltages to said voltage controlled oscillator so as to cause the phase of the output signal from said voltage controlled oscillator to vary by 180 degrees.
4. A system for producing a bi-phase coded output signal comprising:
a voltage controlled oscillator;
a locking frequency reference source;
a three-port circulator for locking the output frequency of said voltage controlled oscillator to the frequency of said locking frequency reference source; and means for applying tuning voltages to said voltage controlled oscillator to cause the phase of the output signal from said voltage controlled oscillator to vary as a function of the applied tuning voltage.
a voltage controlled oscillator;
a locking frequency reference source;
a three-port circulator for locking the output frequency of said voltage controlled oscillator to the frequency of said locking frequency reference source; and means for applying tuning voltages to said voltage controlled oscillator to cause the phase of the output signal from said voltage controlled oscillator to vary as a function of the applied tuning voltage.
5. A method for bi-phase code generation including the steps of:
a) providing a voltage controlled oscillator;
b) providing means for injection locking said voltage controlled oscillator to the frequency of an injected signal such that the power of the signal output by the system is equal to or greater than the power of the injected signal; and c) providing means for applying tuning voltages to said voltage controlled oscillator to cause the phase of the fundamental frequency output signal from said voltage controlled oscillator to vary as a function of the applied tuning voltage.
a) providing a voltage controlled oscillator;
b) providing means for injection locking said voltage controlled oscillator to the frequency of an injected signal such that the power of the signal output by the system is equal to or greater than the power of the injected signal; and c) providing means for applying tuning voltages to said voltage controlled oscillator to cause the phase of the fundamental frequency output signal from said voltage controlled oscillator to vary as a function of the applied tuning voltage.
6. A method for bi-phase code generation including the steps of:
a) providing an amplifier with electrically tunable matching impedance network;
b) inputting a frequency reference signal to said amplifier; and c) applying tuning voltages to said electrically tunable amplifier to cause the phase of the amplified frequency reference signal output from said amplifier to vary as a function of the applied tuning voltage.
a) providing an amplifier with electrically tunable matching impedance network;
b) inputting a frequency reference signal to said amplifier; and c) applying tuning voltages to said electrically tunable amplifier to cause the phase of the amplified frequency reference signal output from said amplifier to vary as a function of the applied tuning voltage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US39973489A | 1989-08-28 | 1989-08-28 | |
| US399,734 | 1989-08-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2021749A1 true CA2021749A1 (en) | 1991-03-01 |
Family
ID=23580756
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2021749 Abandoned CA2021749A1 (en) | 1989-08-28 | 1990-07-23 | Bi-phase code generation and amplification circuit for microwave and millimeter-wave frequencies |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPH0391342A (en) |
| AU (1) | AU6127390A (en) |
| CA (1) | CA2021749A1 (en) |
| IL (1) | IL95188A0 (en) |
| NO (1) | NO903708L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9859948B2 (en) * | 2013-01-08 | 2018-01-02 | Murata Manufacturing Co., Ltd. | Spread spectrum communication device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005245766A (en) * | 2004-03-04 | 2005-09-15 | Uchu Kankyo Hozen Center:Kk | Composition, deodorization material using the same, antibacterial material, coating material, feed additive |
-
1990
- 1990-07-23 CA CA 2021749 patent/CA2021749A1/en not_active Abandoned
- 1990-07-25 IL IL95188A patent/IL95188A0/en unknown
- 1990-08-23 NO NO90903708A patent/NO903708L/en unknown
- 1990-08-23 AU AU61273/90A patent/AU6127390A/en not_active Abandoned
- 1990-08-28 JP JP22641790A patent/JPH0391342A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9859948B2 (en) * | 2013-01-08 | 2018-01-02 | Murata Manufacturing Co., Ltd. | Spread spectrum communication device |
Also Published As
| Publication number | Publication date |
|---|---|
| NO903708D0 (en) | 1990-08-23 |
| IL95188A0 (en) | 1991-06-10 |
| NO903708L (en) | 1991-03-01 |
| AU6127390A (en) | 1991-03-14 |
| JPH0391342A (en) | 1991-04-16 |
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| Date | Code | Title | Description |
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| FZDE | Dead |