CN202424689U - Narrow-band local frequency synthesizer - Google Patents
Narrow-band local frequency synthesizer Download PDFInfo
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- CN202424689U CN202424689U CN2012200417020U CN201220041702U CN202424689U CN 202424689 U CN202424689 U CN 202424689U CN 2012200417020 U CN2012200417020 U CN 2012200417020U CN 201220041702 U CN201220041702 U CN 201220041702U CN 202424689 U CN202424689 U CN 202424689U
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Abstract
The utility model provides a narrow-band local frequency synthesizer. The synthesizer comprises a first stage phase locked loop (PLL) circuit, a direct digital synthesizer (DDS) and a second stage PLL circuit, and the first stage PLL circuit, the DDS and the second stage PLL circuit are arranged in a metal cavity body and are sequentially connected. The narrow-band local frequency synthesizer has the advantages that a mode combining the DDS and double PLL tracking loops is utilized, simultaneously possible stray deterioration in a circuit is prevented well, a good stray performance and a good phase noise performance are achieved, and a good technological foundation for production of the small step high-performance local oscillators is laid.
Description
Technical field
The utility model belongs to electronic information technical field; Be applied to wired, wireless communication industry.The utility model technical problem to be solved is that narrow-band local oscillation is operated in short-wave band, produces the signal of certain frequency scope frequently through the input mark.
Background technology
Narrow-band local oscillation is mainly used in the frequency synthesis of receiver, and the frequency electromagnetic waves that the local oscillator in receiver produces mixes with the high-frequency signal that is received and produces a difference frequency, and this difference frequency is exactly an intermediate frequency.And the device of the generation intermediate frequency in the narrow-band local oscillation narrow-band receiver that to be bandwidth narrow.The main method that produces intermediate-freuqncy signal is frequency division+frequency multiplication+phase-locked loop:
Carry out reference frequency behind the Fractional-N frequency signal to be output as on the corresponding frequency, in the enterprising line output of IF-FRE of using the PLL PHASE-LOCKED LOOP PLL TECHNIQUE to need frequency lock to us in the P frequency multiplication.
The outdoor unit of satellite broadcasting television receiving system is made up of reception antenna, feed, tuner and transmission feeder.Tuner is the equipment foremost in whole satellite broadcasting television receiving system.
It is made up of reactatron, local oscillation circuit and frequency mixer and intermediate level circuit.Tuner is a unique active device of outdoor unit, and it is installed in open air (or in balcony) together with antenna-feedback system; And link to each other with DVB through coaxial cable.The sensitivity of system or signal to noise ratio depend on the performance index of tuner to a great extent.The performance index of tuner are taked any measure again in case selected in receiving system, all will be difficulty very for the raising of the performance of system, all be not so good as to select for use the getting instant result of high-quality tuner.The basic problem of when selecting tuner for use, standing in the breach is the local frequency of choosing to tuner.
Local frequency is produced by local oscillation circuit, and the selection principle of frequency of oscillation at first otherwise the operating frequency that hinders other radio station.Frequency stability in the time of 25 ℃ should: in the positive and negative 1MHz (this is a canonical parameter); It is very important requiring local frequency stable; Otherwise can produce local frequency drift cause can't rating consequence; Therefore in local oscillation circuit, be added with phase-locked loop circuit, thereby guaranteed high stability.In automatic frequency control (AFC) circuit of DVB; Be used for the influence of oscillation-damped frequency change and send into frequency mixer by the high frequency satellite radio television signal that antenna receives through the reactatron amplification, the high-frequency local oscillation signal of local oscillation circuit generation is simultaneously also sent into frequency mixer.After the signal of two different frequencies is sent into frequency mixer; Because frequency mixer is a nonlinear device; The signal that signal that antenna sends here and local oscillator are sent here carries out mixing in frequency mixer, thereby the frequency that produces these signals of intermediate-freuqncy signal (local oscillation signal amplitude selection principle is minimum being as the criterion of intermediate-freuqncy signal distortion to export after the mixing) of a series of different frequencies all should be reduced in first intermediate frequency range in the DVB system.Therefore, signal does not carry out channel and chooses in tuner.The work of choosing of channel is accomplished by the tuner in the DVB, select the channel that will receive, and then this channel carried out a series of technical finesse, finally obtain the vision signal and the audio signal that need.(local frequency is than the high intermediate frequency of signal frequency) be called high local oscillator, and (local frequency is than the low intermediate frequency of signal frequency) just is called low local oscillator when local frequency is lower than signal frequency when local frequency is higher than signal frequency.
The shortcoming of prior art is:
A, adopt simple frequency division+frequency multiplication+PLL PHASE-LOCKED LOOP PLL TECHNIQUE, be difficult to the frequency stability that reaches high, also be difficult to the frequency step that reaches tiny, be difficult to satisfy the modern demand of using;
B, owing to only used frequency division+frequency multiplication+PLL PHASE-LOCKED LOOP PLL TECHNIQUE, cause the phase noise of signal and key index such as spuious to be difficult to accomplish very high.
The utility model content
In order to address the above problem, the utility model provides a kind of narrow-band local oscillation frequency synthesizer, and tiny frequency step can be provided; Output frequency up to the hundreds of megahertz; It is spuious to eliminate DDS, and it is enough high to obtain output frequency, the local oscillation signal that frequency step is enough tiny.
The purpose of the utility model realizes through following technical proposals: the narrow-band local oscillation frequency synthesizer, it mainly is made up of the one-level PLL circuit, numerical frequency direct synthesizer DDS, the secondary PLL circuit that are arranged on metallic cavity inside and connect successively.
The utility model lock additive mixing medium-high frequency export technique is the technology that develops rapidly in recent years and obtain improving constantly.This technology is at first produced the signal of N frequency range by N PLL; Select the modulated signal mixing of frequency mixer with them and low-frequency range through switch, the peak frequency bandwidth of final output signal can realize the stack of N frequency range (frequency bandwidth of spiking output depends on the mixing mode).
The mode of lock additive mixing that remove to adopt the utility model realizes the output of intermediate-freuqncy signal, realizes performance index such as low spuious, low phase noise simultaneously.Numerical frequency direct synthesizer DDS that adds and relevant circuit also let the channel frequency stepping reach below the 0.5Hz, satisfy tiny day by day test stepping, and reduce spuious, low phase noise.
The utility model adopts the pattern of two PLL, and numerical frequency direct synthesizer DDS is set between PLL.
The narrow-band local oscillation frequency synthesizer also comprises the mixting circuit that is arranged between one-level PLL circuit and the secondary PLL circuit; Said mixting circuit is connected with programmable logic device (CPLD), and one-level PLL circuit, secondary PLL circuit all are connected with programmable logic device (CPLD).
One-level PLL circuit also is connected with the SMA socket.
The narrow-band local oscillation frequency synthesizer also comprises 9001 Europlugs, and said 9001 Europlugs are connected with secondary PLL circuit, programmable logic device (CPLD), numerical frequency direct synthesizer DDS respectively.
9001 Europlugs also are connected with power module.
Numerical frequency direct synthesizer DDS is connected with the BMA socket.
Said one-level PLL circuit constitutes by the phase discriminator PD that is connected successively, low pass filter LP, voltage controlled oscillator VCXO with secondary PLL circuit; And the voltage controlled oscillator VCXO of one-level PLL circuit is connected with the phase discriminator PD of one-level PLL circuit; The voltage controlled oscillator VCXO of one-level PLL circuit is connected with numerical frequency direct synthesizer DDS simultaneously, also is connected with the voltage controlled oscillator VCXO of secondary PLL circuit when the phase discriminator PD of said secondary PLL circuit is connected with numerical frequency direct synthesizer DDS.
The locking parameter of the voltage controlled oscillator VCXO of said one-level PLL circuit is 160MHz, and the locking parameter of the voltage controlled oscillator VCXO of said secondary PLL circuit is 40.455MHz ~ 70.455MHz.
For convenient the description abbreviates numerical frequency direct synthesizer DDS as DDS, be a kind of phase-locked loop circuit below with one-level PLL circuit and secondary PLL circuit; DDS can provide tiny frequency step, up to the output frequency of hundreds of megahertz.
PLL possesses the low-pass characteristic of transfer function, and it is spuious to eliminate DDS, and it is enough high to obtain output frequency, the local oscillation signal that frequency step is enough tiny.
Based on foregoing, the design principle of the utility model is: the mode that adopts the two PLL tracking loops of DDS+.The DDS device can provide tiny frequency step, up to the output frequency of hundreds of megahertz, but has caused a large amount of spuious spurious signals to disturb because numeral is blocked, and this has brought chance and challenge for the design of short-wave receiver local vibration source.Adopt the two this modes of PLL tracking loop of DDS+, utilize the low-pass characteristic of the transfer function of PLL, it is spuious to eliminate DDS, and it is enough high to obtain output frequency, the local oscillation signal that frequency step is enough tiny.In this programme, the 10MHz signal reference is latched into 160MHz through one-level PLL circuit, passes through the DDS frequency division then to 20MHz～35MHz, fixes on applying frequency 40.455MHz～70.455 MHz by secondary PLL Circuit lock phase ring lock again.
Simultaneously, SMA socket, 9001 Europlugs, BMA socket are external interface in the utility model; The SMA socket is used for the external frequency source input, and the BMA socket is used for local oscillator output, and 9001 Europlugs are used for the power supply power supply.
In sum; The beneficial effect of the utility model is: the utility model adopts the mode of the two PLL tracking loops of DDS+; Simultaneously finely suppressed the spuious deterioration that possibly occur in the circuit; Realized good spurious performance and phase noise performance, advanced the high-performance local oscillator and established the good technical basis for realizing small step.
Description of drawings
Fig. 1 is the utility model fundamental diagram.
Fig. 2 is the utility model structural representation.
Fig. 3 is the external structure sketch map of the utility model.
Embodiment
The utility model provides a kind of narrow-band local oscillation frequency synthesizer.
Referring to Fig. 1,2, shown in 3: a kind of narrow-band local oscillation frequency synthesizer, it mainly is made up of the one-level PLL circuit, numerical frequency direct synthesizer DDS, the secondary PLL circuit that are arranged on metallic cavity inside and connect successively.
The utility model can provide tiny frequency step, and up to the output frequency of hundreds of megahertz, it is spuious to eliminate DDS, and it is enough high to obtain output frequency, the local oscillation signal that frequency step is enough tiny.
Because lock additive mixing medium-high frequency export technique is the technology that develops rapidly in recent years and obtain improving constantly.This technology is at first produced the signal of N frequency range by N PLL; Select the modulated signal mixing of frequency mixer with them and low-frequency range through switch, the peak frequency bandwidth of final output signal can realize the stack of N frequency range (frequency bandwidth of spiking output depends on the mixing mode).
The mode of lock additive mixing that remove to adopt the utility model realizes the output of intermediate-freuqncy signal, realizes performance index such as low spuious, low phase noise simultaneously.Numerical frequency direct synthesizer DDS that adds and relevant circuit also let the channel frequency stepping reach below the 0.5Hz, satisfy tiny day by day test stepping, and reduce spuious, low phase noise.Therefore the utility model adopts the pattern of two PLL, and DDS is set between PLL.
The narrow-band local oscillation frequency synthesizer also comprises the mixting circuit that is arranged between one-level PLL circuit and the secondary PLL circuit; Said mixting circuit is connected with programmable logic device (CPLD), and one-level PLL circuit, secondary PLL circuit all are connected with programmable logic device (CPLD).
One-level PLL circuit also is connected with SMA socket 2.The narrow-band local oscillation frequency synthesizer also comprises 9001 Europlugs 4, and said 9001 Europlugs 4 are connected with secondary PLL circuit, programmable logic device (CPLD), numerical frequency direct synthesizer DDS respectively.9001 Europlugs 4 also are connected with power module.Numerical frequency direct synthesizer DDS is connected with BMA socket 5.
Said one-level PLL circuit constitutes by the phase discriminator PD that is connected successively, low pass filter LP, voltage controlled oscillator VCXO with secondary PLL circuit; And the voltage controlled oscillator VCXO of one-level PLL circuit is connected with the phase discriminator PD of one-level PLL circuit; The voltage controlled oscillator VCXO of one-level PLL circuit is connected with numerical frequency direct synthesizer DDS simultaneously, also is connected with the voltage controlled oscillator VCXO of secondary PLL circuit when the phase discriminator PD of said secondary PLL circuit is connected with numerical frequency direct synthesizer DDS.The locking parameter of the voltage controlled oscillator VCXO of said one-level PLL circuit is 160MHz, and the locking parameter of the voltage controlled oscillator VCXO of said secondary PLL circuit is 40.455MHz ~ 70.455MHz.
For convenient the description abbreviates numerical frequency direct synthesizer DDS as DDS, be a kind of phase-locked loop circuit below with one-level PLL circuit and secondary PLL circuit; DDS can provide tiny frequency step, up to the output frequency of hundreds of megahertz.
PLL possesses the low-pass characteristic of transfer function, and it is spuious to eliminate DDS, and it is enough high to obtain output frequency, the local oscillation signal that frequency step is enough tiny.
The design principle of the utility model is: the mode that adopts the two PLL tracking loops of DDS+.The DDS device can provide tiny frequency step, up to the output frequency of hundreds of megahertz, but has caused a large amount of spuious spurious signals to disturb because numeral is blocked, and this has brought chance and challenge for the design of short-wave receiver local vibration source.Adopt the two this modes of PLL tracking loop of DDS+, utilize the low-pass characteristic of the transfer function of PLL, it is spuious to eliminate DDS, and it is enough high to obtain output frequency, the local oscillation signal that frequency step is enough tiny.In this programme, the 10MHz signal reference is latched into 160MHz through one-level PLL circuit, passes through the DDS frequency division then to 20MHz～35MHz, fixes on applying frequency 40.455MHz～70.455 MHz by secondary PLL Circuit lock phase ring lock again.
Simultaneously, SMA socket 2,9001 Europlugs 4, BMA socket 5 are external interface in the utility model; The SMA socket is used for the external frequency source input, and BMA socket 5 is used for local oscillator output, and 9001 Europlugs 4 are used for the power supply power supply.Simultaneously, the utility model adopts panel trip bolt 1 that the circuit board that foregoing circuit constitutes is fixed on metallic cavity inside.
The utility model adopts the mode of the two PLL tracking loops of DDS+; Simultaneously finely suppressed the spuious deterioration that possibly occur in the circuit; Realized good spurious performance and phase noise performance, advanced the high-performance local oscillator and established the good technical basis for realizing small step.
As above above-mentioned, just can realize the utility model preferably.
Claims (8)
1. the narrow-band local oscillation frequency synthesizer is characterized in that: mainly be made up of the one-level PLL circuit, numerical frequency direct synthesizer DDS, the secondary PLL circuit that are arranged on metallic cavity inside and connect successively.
2. narrow-band local oscillation frequency synthesizer according to claim 1; It is characterized in that: also comprise the mixting circuit that is arranged between one-level PLL circuit and the secondary PLL circuit; Said mixting circuit is connected with programmable logic device (CPLD), and one-level PLL circuit, secondary PLL circuit all are connected with programmable logic device (CPLD).
3. narrow-band local oscillation frequency synthesizer according to claim 2 is characterized in that: one-level PLL circuit also is connected with SMA socket (2).
4. narrow-band local oscillation frequency synthesizer according to claim 2; It is characterized in that: also comprise 9001 Europlugs (4), said 9001 Europlugs (4) are connected with secondary PLL circuit, programmable logic device (CPLD), numerical frequency direct synthesizer DDS respectively.
5. narrow-band local oscillation frequency synthesizer according to claim 4 is characterized in that: 9001 Europlugs (4) also are connected with power module.
6. narrow-band local oscillation frequency synthesizer according to claim 2 is characterized in that: numerical frequency direct synthesizer DDS is connected with BMA socket (5).
7. according to any described narrow-band local oscillation frequency synthesizer among the claim 1-6; It is characterized in that: said one-level PLL circuit constitutes by the phase discriminator PD that is connected successively, low pass filter LP, voltage controlled oscillator VCXO with secondary PLL circuit; And the voltage controlled oscillator VCXO of one-level PLL circuit is connected with the phase discriminator PD of one-level PLL circuit; The voltage controlled oscillator VCXO of one-level PLL circuit is connected with numerical frequency direct synthesizer DDS simultaneously, also is connected with the voltage controlled oscillator VCXO of secondary PLL circuit when the phase discriminator PD of said secondary PLL circuit is connected with numerical frequency direct synthesizer DDS.
8. narrow-band local oscillation frequency synthesizer according to claim 7; It is characterized in that: the locking parameter of the voltage controlled oscillator VCXO of said one-level PLL circuit is 160MHz, and the locking parameter of the voltage controlled oscillator VCXO of said secondary PLL circuit is 40.455MHz ~ 70.455MHz.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012200417020U CN202424689U (en) | 2012-02-09 | 2012-02-09 | Narrow-band local frequency synthesizer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012200417020U CN202424689U (en) | 2012-02-09 | 2012-02-09 | Narrow-band local frequency synthesizer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202424689U true CN202424689U (en) | 2012-09-05 |
Family
ID=46749412
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2012200417020U Expired - Lifetime CN202424689U (en) | 2012-02-09 | 2012-02-09 | Narrow-band local frequency synthesizer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202424689U (en) |
-
2012
- 2012-02-09 CN CN2012200417020U patent/CN202424689U/en not_active Expired - Lifetime
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120905 |
|
| CX01 | Expiry of patent term |