CN203399086U - Frequency source based on DDS harmonic wave extraction technique - Google Patents
Frequency source based on DDS harmonic wave extraction technique Download PDFInfo
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- CN203399086U CN203399086U CN201320475603.8U CN201320475603U CN203399086U CN 203399086 U CN203399086 U CN 203399086U CN 201320475603 U CN201320475603 U CN 201320475603U CN 203399086 U CN203399086 U CN 203399086U
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Abstract
The utility model relates to a frequency source. In the prior art, a frequency source made of DDS devices is large in output stray and complex in structure, so that the utility model discloses a frequency source based on a DDS harmonic wave extraction technique. The frequency source based on the DDS harmonic wave extraction technique comprises a DDS frequency source which is composed of an oscillator, a control system and a DDS, and the frequency source based on the DDS harmonic wave extraction technique is characterized by also comprising a harmonic wave frequency selection circuit, an amplifier, a band pass filter and a frequency multiplier. The harmonic wave frequency selection circuit is connected with the DDS to extract a DDS output frequency higher harmonic signal and sends the signal into the amplifier. The band pass filter is connected with the amplifier to carry out filtering on a signal output by the amplifier and remove outband interference signals. The frequency multiplier is connected with the filter to carry out frequency multiplication on a signal output by the filter and improve the signal frequency. With the frequency source based on the DDS harmonic wave extraction technique, a frequency multiplication link is shortened, the circuit structure is simplified, and the cost and energy consumption is reduced.
Description
Technical field
The utility model relates to Microwave Frequency Source, particularly a kind of frequency source based on DDS harmonic wave extractive technique.
Background technology
In microwave technology, frequency source is an important core component, is undertaking and is providing task stable, accurate operating frequency for system.In requiring the frequency source of broader bandwidth, proportion synthetic technology usually.
DDS(Direct Digital Synthesizer, DDS Direct Digital Frequency Synthesizers, is called for short frequency synthesizer, belongs to analog integrated circuit, sometimes also referred to as DDS chip) what adopt is digital structure, in very many-sided performance index far beyond legacy frequencies synthetic technology.When existing Direct Digital Frequency Synthesizers is due to chip operation on market, be subject to the operating rate restriction of the integrated DAC in external clock and inside and ROM, make the highest frequency of its output limited, the DDS chip that adopts in the market the techniques such as CMOS, TTL to make, when reference clock, (frequency is ω
s) determine after, the reference frequency output of DDS is generally 0～40% ω
s, conventionally only can synthesize tens megahertzes to the signal of hundreds of megahertz.
DDS provides different voltage amplitudes from phase place concept according to different phase places, i.e. phase place-sine amplitude conversion, and last filtering, exports required frequency signal.DDS is mainly by phase accumulator, and wave memorizer and digital to analog converter (DAC) form.When DDS works, phase accumulator is usingd pre-set frequency control word and is carried out linear superposition as step-length under the control of reference clock frequency, obtain phase code wave memorizer is carried out to addressing output amplitude code, by DAC, be converted to staircase waveform and after low pass filter is level and smooth, obtain corresponding synthesized frequency signal again.The method that the existing DDS of utilization produces high-frequency signal mainly contains two kinds: a kind of method is to adopt DDS as the reference-input signal of phase-locked loop circuit, utilizes phase-locked loop circuit to carry out frequency multiplication to obtain required high-frequency signal to the lower signal of frequency.But the circuit structure of this scheme comparatively complexity and the response time relatively long.Another kind method is that the signal of the lower frequency (MHz level) of DDS device output is carried out to the operations such as frequency multiplication, amplification, frequency division, filtering to obtain high-frequency signal (GHz level).But this scheme is subject to, and number of elements is many, circuit structure is complicated, energy consumption is high, volume is large, the restriction of the spuious shortcoming such as large.The high frequency frequency synthesizer based on DDS device having had in practical application is at present to pass through first scheme, first low frequency signal frequency multiplication is arrived to higher frequency, after frequency-selecting, carry out again frequency multiplication, frequency-selecting until obtain required high frequency frequency, and export after this high-frequency signal being amplified to the power of requirement.
DDS device frequency synthetic schemes can be directly synthetic signal frequency low, utilize the synthetic low frequency signal of DDS device to carry out many times frequency multiplication, mixing, filtering, amplify the synthetic schemes that waits operation to obtain high-frequency signal, due to many times frequency multiplication, need a large amount of frequency multipliers, frequency mixer, filter, amplifier etc. and cause circuit complicated, bulky, cost and power consumption are too high, while many times frequency multiplication, mixing, the links such as frequency division can be introduced a large amount of spuious, make the poor shortcoming of the spuious inhibition of DDS more outstanding, increased the weight of output spuious, complex structure consequently, spuious large and be difficult to adopt filter to carry out filtering, and greatly weakened the high advantage of DDS frequency step resolution.
Utility model content
Technical problem to be solved in the utility model, it is exactly the frequency source forming for prior art DDS device, spuious large, the baroque shortcoming of frequency synthesis output, provides a kind of frequency source based on DDS harmonic wave extractive technique, reduces spuious, simplification circuit structure.
The utility model solve the technical problem, the technical scheme adopting is, frequency source based on DDS harmonic wave extractive technique, comprise DDS frequency source, described DDS frequency source consists of oscillator, control system and DDS, it is characterized in that, also comprise harmonic wave frequency selection circuit, amplifier, band pass filter and frequency multiplier; Described harmonic wave frequency selection circuit is connected with DDS, extracts described DDS output frequency high order harmonic component signal input amplifier; Described band pass filter is connected with amplifier, and amplifier output signal is carried out to filtering processing, the outer interference signal of filtering band; Described frequency multiplier is connected with filter, and filter output signal is carried out to process of frequency multiplication, improves signal frequency.
In actual experiment, find, the frequency spectrum of DDS chip output comprises synthetic signal frequency ω
dDSharmonic frequency ω with this signal
m, and the relational expression of the two is ω
m=n ω
s± ω
dDS, n=0, ± 1, ± 2......(ω
sfor reference frequency), therefore can directly utilize the harmonic wave of DDS composite signal to obtain the signal of upper frequency.The technical solution of the utility model, after DDS chip, add a harmonic wave frequency selection circuit, required harmonic frequency is screened, be then amplified to required power (power that frequency multiplier is required), by simple first overtone, just can obtain required frequency signal.
Concrete, described harmonic wave frequency selection circuit is SAW (Surface Acoustic Wave) filter.
Concrete, described band pass filter is SAW (Surface Acoustic Wave) filter.
The function of harmonic wave frequency selection circuit is equivalent to a band pass filter exactly.Because Surface Acoustic Wave Filter has that operating frequency is high, pass band, selecting frequency characteristic is good, volume is little and the feature such as lightweight, and can adopt the production technology identical with integrated circuit, manufacture simple, cost is low, the high conformity of frequency characteristic is suitable for harmonic wave frequency selection circuit of the present utility model and band pass filter very much.
Further, described harmonic wave frequency selection circuit is operated in L-band, between described band pass filter and frequency multiplier, be connected with power divider, described power divider is divided into two-way by band pass filter output signal, 4 frequency multipliers of leading up to are exported C-band signals, and 8 frequency multipliers of leading up to are exported X-band signals.
Harmonic wave frequency selection circuit is operated in L-band, selects the band pass filter of the about 1.5GHz of passband centre frequency, can directly from the high order harmonic component of DDS output, extract the harmonic frequency of 1～2GHz.This harmonic frequency is amplified through amplifier and band pass filter filtering band disturbs outward, then by power divider, band pass filter output signal is divided into two-way, 4 frequency multipliers of leading up to can be exported the C-band signal of 4～8GHz, and 8 frequency multipliers of leading up to can be exported the X-band signal of 8～12.5GHz.
Further, described 4 frequency multiplier outputs are connected with dielectric filter, and described 8 frequency multiplier outputs are connected with cavity body filter.
In order to improve the signal to noise ratio of output frequency signal, the utility model is connected with dielectric filter at 4 frequency multiplier outputs; 8 frequency multiplier outputs are connected with cavity body filter.Dielectric filter utilize low-loss, high-k, frequency-temperature coefficient and the thermal coefficient of expansion of medium ceramic material little, can bear that the features such as high power design and produce, be characterized in that little, the resistance to power of insertion loss is good, narrow bandwidth, be particularly suitable for the filtering of C-band signal.Cavity body filter is formed by metal integral cutting, sound construction, the wide high conformity of frequency coverage, volume is little, reliability is high, stable and reliable for performance in full temperature, the filtering of the X-band signal of very applicable 8～12.5GHz.
The beneficial effects of the utility model are, overcome the low shortcoming of DDS device output signal frequency, greatly improve the DDS device frequency synthesis upper limit, greatly shortened frequency multiplication link, reduced the use of filtering, amplifying device, simplified circuit structure, dwindle volume, reduced cost and energy consumption, improved frequency step resolution, and greatly shortened design and the debugging cycle of circuit, expanded the range of application of DDS device.The utility model can synthesize the signal of any high frequency within the specific limits by changing the program control DDS device of FREQUENCY CONTROL interface, thereby makes the present utility model design can be widely used in the equipment such as radar, microwave apparatus.
Below in conjunction with the drawings and the specific embodiments, describe the technical solution of the utility model in detail.
Accompanying drawing explanation
Fig. 1 is the utility model electrical block diagram;
Fig. 2 is embodiment electrical block diagram.
Embodiment
The frequency source of the utility model based on DDS harmonic wave extractive technique, structure as shown in Figure 1, comprises DDS frequency source, harmonic wave frequency selection circuit, amplifier, band pass filter and frequency multiplier.In Fig. 1, DDS frequency source consists of oscillator, control system and DDS chip.The frequency spectrum of DDS chip output is except synthetic signal frequency ω
dDSthe harmonic frequency ω that also comprises this signal outward,
m, and ω
m=n ω
s± ω
dDS, n=0, ± 1, ± 2...... is harmonic number, ω
sfor reference frequency.The utility model utilizes harmonic wave frequency selection circuit to be connected with DDS, extracts the high order harmonic component signal (high-frequency signal) of DDS output, and this high-frequency signal input amplifier is carried out to power amplification.The signal of amplifier output carries out filtering processing by the band pass filter connecting, the outer interference signal of filtering band.Band pass filter output signal output is admitted to frequency multiplier, through simple one-level process of frequency multiplication, just can obtain the frequency-doubled signal needing.
Embodiment
The frequency source of this example based on DDS harmonic wave extractive technique, structure as shown in Figure 2.This frequency source comprises: the DDS frequency source that oscillator, control system and DDS chip form; SAW (Surface Acoustic Wave) filter as harmonic wave frequency selection circuit; Amplifier; As the SAW (Surface Acoustic Wave) filter of band pass filter and two frequency multiplication branch roads of power divider connection.In this example, as the SAW (Surface Acoustic Wave) filter of harmonic wave frequency selection circuit, be operated in L-band, can directly from the high order harmonic component of DDS output, extract the L-band signal of 1～2GHz frequency.This L-band signal is amplified to the power needing, the requirement of processing to meet subsequent conditioning circuit through amplifier.As shown in Figure 2, the L-band signal of this routine amplifier output, after another SAW (Surface Acoustic Wave) filter filtering, is divided into two branch roads by power divider by signal, 4 frequency multipliers of leading up to are exported the C-band signal of 4～8GHz, and 8 frequency multipliers of leading up to are exported the X-band signal of 8～12.5GHz.Like this, this routine frequency source can be exported two paths of signals, for different systems provides reference frequency signal.
In order to improve the signal to noise ratio of output frequency signal, in this example, at 4 frequency multiplier outputs, be connected with dielectric filter, C-band signal is carried out to filtering processing, obtain purer frequency signal.Same, at 8 frequency multiplier outputs, be connected with cavity body filter, X-band signal is carried out to filtering processing.
Claims (5)
1. the frequency source based on DDS harmonic wave extractive technique, comprises DDS frequency source, and described DDS frequency source consists of oscillator, control system and DDS, it is characterized in that, also comprises harmonic wave frequency selection circuit, amplifier, band pass filter and frequency multiplier; Described harmonic wave frequency selection circuit is connected with DDS, extracts described DDS output frequency high order harmonic component signal input amplifier; Described band pass filter is connected with amplifier, and amplifier output signal is carried out to filtering processing, the outer interference signal of filtering band; Described frequency multiplier is connected with filter, and filter output signal is carried out to process of frequency multiplication, improves signal frequency.
2. the frequency source based on DDS harmonic wave extractive technique according to claim 1, is characterized in that, described harmonic wave frequency selection circuit is SAW (Surface Acoustic Wave) filter.
3. the frequency source based on DDS harmonic wave extractive technique according to claim 1, is characterized in that, described band pass filter is SAW (Surface Acoustic Wave) filter.
4. according to the frequency source based on DDS harmonic wave extractive technique described in claim 1～3 any one, it is characterized in that, described harmonic wave frequency selection circuit is operated in L-band, between described band pass filter and frequency multiplier, be connected with power divider, described power divider is divided into two-way by band pass filter output signal, 4 frequency multipliers of leading up to are exported C-band signals, and 8 frequency multipliers of leading up to are exported X-band signals.
5. the frequency source based on DDS harmonic wave extractive technique according to claim 4, is characterized in that, described 4 frequency multiplier outputs are connected with dielectric filter, and described 8 frequency multiplier outputs are connected with cavity body filter.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201320475603.8U CN203399086U (en) | 2013-08-06 | 2013-08-06 | Frequency source based on DDS harmonic wave extraction technique |
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|---|---|---|---|
| CN201320475603.8U CN203399086U (en) | 2013-08-06 | 2013-08-06 | Frequency source based on DDS harmonic wave extraction technique |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104217184A (en) * | 2014-04-18 | 2014-12-17 | 天津工业大学 | Novel UHF (Ultra High Frequency) RFID (Radio Frequency Identification Device) reader transmitter |
| CN108092663A (en) * | 2017-12-26 | 2018-05-29 | 海能达通信股份有限公司 | Frequency generating apparatus and frequency generating method |
| CN112702059A (en) * | 2020-12-11 | 2021-04-23 | 兰州空间技术物理研究所 | Frequency synthesizer for cesium atomic clock |
-
2013
- 2013-08-06 CN CN201320475603.8U patent/CN203399086U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104217184A (en) * | 2014-04-18 | 2014-12-17 | 天津工业大学 | Novel UHF (Ultra High Frequency) RFID (Radio Frequency Identification Device) reader transmitter |
| CN108092663A (en) * | 2017-12-26 | 2018-05-29 | 海能达通信股份有限公司 | Frequency generating apparatus and frequency generating method |
| CN108092663B (en) * | 2017-12-26 | 2022-01-21 | 海能达通信股份有限公司 | Frequency generating device and frequency generating method |
| CN112702059A (en) * | 2020-12-11 | 2021-04-23 | 兰州空间技术物理研究所 | Frequency synthesizer for cesium atomic clock |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140115 Termination date: 20140806 |
|
| EXPY | Termination of patent right or utility model |