CN105245225B - Low-frequency range arrowband synthetic source is converted into the circuit of high-frequency-band broadband synthetic source - Google Patents

Abstract

The invention provides the circuit that a kind of low-frequency range arrowband synthetic source is converted into high-frequency-band broadband synthetic source, the circuit includes low frequency synthetic source and change-over circuit, one end ground connection of low frequency synthetic source, the other end is connected with change-over circuit, change-over circuit is connected with synthesis source output terminal, change-over circuit is made up of five main circuits being connected, and main circuit includes the first main circuit, the second main circuit, the 3rd main circuit, the 4th main circuit and the 5th main circuit.The circuit passes through the modes such as frequency dividing, frequency multiplication, filtering and amplification, low frequency synthetic source is converted into the frequency band signals of 9 kinds of different multiples, the switching of a switch and an either-or switch is selected to select by controlling one four, the frequency range of different multiples is combined, then by being mixed and amplifying filtering twice, frequency range is finally given in 5GHz between 10GHz, the synthetic source with a width of 5GHz.Whole circuit control is simple, does not introduce phase-locked loop, whole circuit small volume, and cost is low.

Description

A circuit for converting a low-band narrow-band synthetic source into a high-band wide-band synthetic source

technical field

The invention relates to the technical field of synthesis of broadband synthesis sources, in particular to a circuit for converting a low-frequency band narrow-band synthesis source into a high-frequency band broadband synthesis source.

Background technique

Among the various measuring instruments at the present stage, a broadband synthetic source is mainly used as the local oscillator source of the machine. By performing up-down conversion and segmental filtering on the local oscillator source, the desired frequency band signals are obtained, and then the whole machine is completed. Various functions, so the signal index of the local oscillator determines the signal index of the whole machine. Under the premise of pursuing high indicators of local oscillators, how to reduce the power consumption of local oscillators as much as possible, simplify the control of local oscillators, reduce the cost of local oscillators, and improve the stability of local oscillators is the current A problem faced by the development of the vibration source.

In the synthesis scheme of the present broadband synthesis source, the main schemes include frequency multiplication/frequency division, direct digital synthesis technology (DDS) and phase-locked loop technology (PLL). Among them, the simple frequency division/multiplication scheme, in order to obtain the high-band broadband synthesis source, needs to perform frequency multiplication processing on the basis of the broadband low-frequency source, while using the narrow-band low-frequency synthesis source, only through simple multiplication and division operations, it is impossible The frequency band broadband signal source covers the whole frequency band. Although Direct Digital Synthesis (DDS) has the advantages of high resolution and high frequency accuracy, its biggest disadvantage is that the operating frequency is low, and the output frequency generally does not exceed 500MHz. At the same time, the phase quantization noise and D/ The magnitude quantization noise introduced by the A-transform can lead to a high overall output noise level. The phase-locked loop technology is the mainstream frequency synthesis technology at this stage.

The phase-locked loop circuit is mainly composed of a phase detector (PD), a loop filter (LPF), a voltage-controlled oscillator (VCO) and a counting frequency divider. Based on a voltage-controlled oscillator (VCO) with a bandwidth of 5GHz-10GHz and a reference frequency point with extremely high indicators, the same frequency as the reference frequency point can be obtained by dividing the frequency of the broadband VCO feedback signal by 1/N , the two signals are sent to the phase detector for phase detection, and the obtained phase detection error adjusts the VCO, and finally a synthetic source with the same accuracy as the reference frequency is obtained. If a single loop is simply used for loop phase-locking, because the signal phase noise index in the band will deteriorate by multiples according to the phase noise deterioration formula, satisfactory signal indexes cannot be obtained, so usually a multi-loop phase-locking scheme is adopted, and the The 1/N frequency division of the broadband VCO feedback signal in the single-loop phase-locking is replaced by a sampling loop, and the signal obtained by sampling the VCO and the sampling loop M times is phase-identified with the reference signal, so that the in-band phase of the broadband composite source output signal is finally obtained The noise index is determined by the sampling loop, and the in-band phase noise index of the output signal is optimized to a certain extent. However, the control of the multi-loop phase-locking scheme is too complicated, the circuit is bulky, and the introduction of multiple loops will increase the cost of the circuit, increase the power consumption of the circuit, and reduce the stability of the circuit. The broadband synthesis source obtained by using the phase-locked loop scheme will increase the frequency switching time because the loop locking needs a certain time. At the same time, the more phase-locked loops are introduced, the longer the frequency switching time is required.

Contents of the invention

Aiming at the problems of complex control, bulky circuit, high cost and insufficient stability of the circuit in the existing phase-locked loop circuit, the invention provides a circuit for converting a low-frequency narrow-band synthesis source into a high-frequency broadband synthesis source.

The present invention adopts following technical scheme:

The circuit for converting the low-frequency narrowband synthesis source into the high-frequency broadband synthesis source, including the low-frequency synthesis source and the conversion circuit, one end of the low-frequency synthesis source is grounded, the other end is connected to the conversion circuit, and the conversion circuit is connected to the synthesis source output end, and the conversion circuit consists of five connected main circuits, the main circuits include a first main circuit, a second main circuit, a third main circuit, a fourth main circuit and a fifth main circuit.

Preferably, the first main circuit includes a first four-frequency divider, an eight-frequency divider, a first amplifier, a low-pass filter, and a power divider connected in series, and the second main circuit includes a two-frequency divider and a four-selection frequency divider. One switch, one output terminal of the two-frequency divider is directly connected to the first input terminal of the four-choice one switch, and the other output terminal of the two-frequency divider is connected to the second input terminal of the four-choice one switch through the triple frequency multiplier, and the four-choice The output end of a switch is connected with the second four-frequency divider, the second four-frequency divider is connected with the first mixer, and the first mixer is connected with the combiner; the third main circuit is directly connected with the four-select-one switch The third input end, the power divider is respectively connected with the first mixer and combiner.

Preferably, the fourth main circuit includes a frequency doubler, one output of the doubler is connected to the fourth input of the one-of-four switch, and the other output of the doubler is connected to the first diode ; The fifth main circuit includes a second diode and an alternative switch, the second diode is connected to an input terminal of the alternative switch, and the other input terminal of the alternative switch is in phase with the first diode connected, the output end of the one-of-two switch is connected with a second mixer, the second mixer is connected with a second amplifier, the second amplifier is connected with a band-pass filter, and the band-pass filter is connected with the synthesis source output end; The combiner is connected to the second mixer.

Preferably, both the first diode and the second diode are Schottky barrier diodes.

Preferably, the frequency range of the low-frequency synthesis source is between 1607MHz and 1642MHz, and the bandwidth of the low-frequency synthesis source is 35MHz.

The beneficial effects that the present invention has are:

The invention provides a circuit for converting a low-frequency narrow-band synthesis source into a high-frequency broadband synthesis source. The circuit converts the low-frequency synthesis source into 9 frequency band signals with different multiples by means of frequency division, frequency multiplication, filtering and amplification. A four-to-one switch and a two-to-one switch are used to combine frequency bands of different multiples, and then through two times of frequency mixing and amplification and filtering, finally a synthetic source with a frequency range of 5GHz to 10GHz and a bandwidth of 5GHz is obtained. The circuit only needs to control the frequency switching of the low-frequency narrow-band synthetic source and two switches to complete the conversion of the synthetic source. The circuit control is simple, no phase-locked loop is introduced, and the entire circuit is small in size and low in cost. Compared with the existing phase-locked loop circuit, the twice-mixed phase-locked scheme adopted by the present invention does not introduce loop phase-locked time, reduces the frequency switching time of the broadband synthesis source, and obtains a high-index broadband synthesis source at the same time.

Description of drawings

Fig. 1 is a circuit diagram of a circuit for converting a low frequency band narrowband synthesis source into a high frequency band broadband synthesis source.

Detailed ways

The present invention is specifically described below in conjunction with accompanying drawing:

Combined with Figure 1, the circuit for converting the low-frequency narrowband synthesis source into the high-frequency broadband synthesis source includes the low-frequency synthesis source F _1.6GHz and a conversion circuit. One end of the low-frequency synthesis source is grounded, and the other end is connected to the conversion circuit. The low-frequency synthesis source is an input signal with low phase noise and high stability, and the low-frequency synthesis source determines the phase noise index and frequency stability of the final high-band broadband synthesis source. The frequency range of the low-frequency synthesis source F _1.6GHz is between 1607MHz and 1642MHz, and the bandwidth of the low-frequency synthesis source is 35MHz.

The conversion circuit is connected with a synthesis source output end, and the conversion circuit is composed of five connected main circuits. The main circuits include a first main circuit, a second main circuit, a third main circuit, a fourth main circuit and a fifth main circuit.

The first main circuit includes a first four-frequency divider 1 , an eighth frequency divider 2 , a first amplifier 3 , a low-pass filter 4 and a power divider 5 which are serially connected in sequence.

The second main circuit comprises a two-frequency divider 6 and a four-choice switch 8, an output end of the two-frequency divider 6 is directly connected to the first input end of the four-choice switch 8, and the other output end of the two-frequency divider 6 passes through The frequency tripler 7 is connected to the second input terminal of the one-of-four switch 8, and the output terminal of the one-to-four switch 8 is connected to the second four-frequency divider 9, and the second four-frequency divider 9 is connected to the first mixer 10 , the first mixer 10 is connected to a combiner 11 . The power divider 5 in the first main circuit is connected to the first mixer 10 and the combiner 11 respectively.

The third main circuit is directly connected to the third input terminal of the one-of-four switch 8 .

The fourth main circuit includes a frequency doubler 12, an output end of the frequency doubler 12 is connected to the fourth input end of the one-of-four switch 8, and the other output end of the frequency doubler 12 is connected with a first diode 13 .

The fifth main circuit comprises a second diode 14 and an alternative switch 15, the second diode 14 is connected to an input terminal of the alternative switch 15, and the other input terminal of the alternative switch 15 is connected to the first input terminal of the alternative switch 15. The diodes 13 are connected, the output terminal of the one-of-two switch 15 is connected with a second mixer 16, the second mixer 16 is connected with a second amplifier 17, and the second amplifier 17 is connected with a bandpass filter 18, with The pass filter 18 is connected to the synthesis source output; the combiner 11 is connected to the second mixer 16 .

Both the first diode and the second diode are Schottky barrier diodes. Using the nonlinear characteristics of the first diode, the 4th harmonic and 6th harmonic of the low-frequency synthesis source F _1.6GHz can be obtained; Utilizing the nonlinear characteristics of the second diode, the 3rd and 5th harmonics of the low-frequency synthesis source F _1.6GHz can be obtained.

The frequency band signal input to the first mixer by the power divider 5 is F _IF1 , the frequency band signal input by the second four-frequency divider to the first mixer is F _LO1 , and the frequency band signal input to the second mixer by the combiner is F _IF2 , the frequency band signal input to the second mixer by the output end of the two-selection switch is F _LO2 , and the frequency band signal output by the output end of the synthesis source is F _OUT .

The calculation formula and frequency range of each frequency band signal are:

Formula 1: (Frequency range: 50.21875MHz～51.25MHz)

Formula 2:

Formula 3:

Formula 4:

Formula 5: F _OUT ＝F _IF2 +F _LO2 (frequency range: 54Hz～10GHz)

Table 1 The specific mixing operation of the output frequency of each frequency band signal

Table 1 (Continued) The specific mixing operation of the output frequency of each frequency band signal

Table 1 (Continued) The specific mixing operation of the output frequency of each frequency band signal

Of course, the above descriptions are not intended to limit the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or replacements made by those skilled in the art within the scope of the present invention shall also belong to the present invention. protection scope of the invention.

Claims (3)

1. A circuit for converting a low-frequency band narrow-band synthesis source into a high-frequency band broadband synthesis source, characterized in that it includes a low-frequency synthesis source and a conversion circuit, one end of the low-frequency synthesis source is grounded, the other end is connected to a conversion circuit, and the conversion circuit is connected to a synthesis source output Terminal, the conversion circuit is composed of five connected main circuits, the main circuit includes the first main circuit, the second main circuit, the third main circuit, the fourth main circuit and the fifth main circuit; The first main circuit includes a first four-frequency divider, an eight-frequency divider, a first amplifier, a low-pass filter, and a power divider connected in series in sequence, and the second main circuit includes a two-frequency divider and a one-of-four switch, One output end of the two-frequency divider is directly connected to the first input end of the four-choice switch, and the other output end of the two-frequency divider is connected to the second input end of the four-choice switch through a triple frequency multiplier. The output end is connected with the second four-way frequency divider, the second four-way frequency divider is connected with the first mixer, and the first mixer is connected with the combiner; the third main circuit is directly connected with the third input of the one-of-four switch terminal, the power splitter is connected to the first mixer and combiner respectively; The fourth main circuit includes a frequency doubler, an output end of the frequency doubler is connected to the fourth input end of a four-select-one switch, and the other output end of the frequency doubler is connected with a first diode; the fifth The main circuit includes a second diode and an alternative switch, the second diode is connected to one input terminal of the alternative switch, the other input terminal of the alternative switch is connected to the first diode, and the second diode is connected to the first input terminal of the alternative switch. The output end of a selection switch is connected with a second mixer, the second mixer is connected with a second amplifier, the second amplifier is connected with a band-pass filter, and the band-pass filter is connected with the synthesis source output end; connected to the second mixer. 2. The circuit for converting the low-band narrowband synthesis source into the high-frequency broadband synthesis source according to claim 1, characterized in that, both the first diode and the second diode are Schottky barrier diodes. 3. according to any one of claim 1 and 2, the low frequency band narrowband synthesis source is converted into the circuit of the high frequency band broadband synthesis source, it is characterized in that, the frequency range of the low frequency synthesis source is between 1607MHz to 1642MHz, and the low frequency synthesis The bandwidth of the source is 35MHz.