JPS63175507A - Microwave frequency converting circuit - Google Patents

Abstract

PURPOSE:To attain the small size in the local oscillation system and the low cost by using a frequency multiplier so as to multiply an output of a common local oscillation source at an optional multiple thereby obtaining a local oscillation input to plural frequency converters. CONSTITUTION:A 1st local oscillation circuit of a 1st frequency converter 21 employs only the common local oscillation source 22 without any multiplier and a 2nd local oscillation circuit of a 2nd frequency converter 25 consists of a multiplier 27 whose number of multiple is N and the common local oscillation source 22. A base hand signal frequency fl is lifted by a 1st local oscillation frequency fL by the 1st frequency converter 21 and becomes an intermediate frequency (IF)f2. The signal is amplified to a prescribed level by an IF band amplifier 24 and increased by a local oscillation frequency NfL at the 2nd frequency converter 25 and converted into a transmission frequency f3. Thus, only one set of local oscillator is enough for the application and the external size is decreased and the adjustment time is reduced, resulting in reducing the cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a microwave frequency conversion circuit used in a microwave transmitter/receiver.

(Prior Art) As a frequency conversion circuit configuration in the microwave band, a superheterodyne system using a mixer is usually used. In particular, when the baseband signal frequency and the transmission or reception frequency are significantly different and the transmission or reception frequency bandwidth is wide, it is necessary to connect two or more stages of conversion circuits in cascade. In such a case, in order to select a predetermined transmission or reception frequency, a method is used in which the local oscillator of one of the frequency conversion circuits is set to a predetermined oscillation frequency.

FIG. 6 shows the configuration of a conventional transmission frequency conversion device using a double conversion method. First, the baseband signal frequency f is raised by the first frequency converter 1 by the oscillation frequency fLs of the first local oscillator 2,
The intermediate frequency (Ip) is ft. This intermediate frequency (IP
) fs is an F band BPF (band pass filter) 3 in which unnecessary waves such as local oscillation leakage are suppressed, and an IF band width filter 4
amplified to a predetermined level. Next, f is raised by the local oscillation frequency NfL* by the second frequency converter 5 and converted to the transmission frequency f, and unnecessary waves are suppressed by the transmission BPF 6, resulting in a high output (not shown). Output to an amplifier etc.

In this example, the second frequency converter 50 local oscillation circuit is composed of a second local oscillator 7 and a frequency multiplier 8,
The multiplication order is set to N (N>2). Second frequency converter 50 The multiplier 8 may be omitted if a local oscillator can be constructed that can obtain the necessary local oscillation performance such as sufficient frequency stability and output level in the local frequency NfL* band. There is also. In FIG. 6, the frequency band f of the transmission frequency,
To select a predetermined transmit frequency within ±AJ'l, the second
This is done by setting the oscillation frequency of the local oscillator 7 to a predetermined value.

The above frequency correspondence is shown by the formula below. However, the first and second
It is assumed that the output frequencies of the frequency converters 1 and 5 are set to the upper sideband.

f*=fX+fLt fs ±nf s =fx 10N (f L! soil f
L! ) = (fs +f Ls+Nf Lx )±
NΔf Lx Therefore, the variable setting bandwidth BWL of the second local oscillator 7 and the owned output bandwidth BWM of the multiplier 8, BWL=shimu fm
/N I BWM=±Δf.

becomes.

(Problems to be Solved by the Invention) As described above, the conventional microwave frequency conversion circuit has the following drawbacks.

(1) Since a dedicated local oscillator is required for each frequency converter, the cost is high and the external size is large.

In particular, in order to obtain sufficient frequency stability, if a phase-locked oscillator using a crystal reference oscillator is used as a local oscillator, the cost will be extremely high and the external dimensions will be large.

(2) The local oscillation system bandwidth for selecting the desired transmission frequency is approximately the same as the transmission frequency bandwidth at the output end of the multiplier, and approximately 1/N (N
is the multiplication order of the multiplier), it is necessary to widen the band of the multiplier and local oscillator, which increases the adjustment time and causes deterioration of characteristics such as output level and noise performance.

(8) In the above explanation, the transmitting frequency converter circuit (up converter) was described, but in the case of the receiving frequency converter circuit (down converter), the configuration is exactly the same if the signal flow is reversed in the above explanation. It is clear that they have similar drawbacks.

(In the case of a multi-stage conversion circuit system in which three or more stages of frequency converters are cascaded, the number of required local oscillators increases, so the above-mentioned drawback becomes even greater.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and provides a microwave frequency conversion circuit that minimizes the number of local oscillators and can reduce the total bandwidth of the local oscillation system for selecting transmission or reception frequencies. With the goal.

[Structure of the invention]

(Means for Solving the Problems) That is, in the microwave frequency conversion circuit according to the present invention, in a multi-stage type having two or more stages of frequency converters, the local oscillation input hole of each frequency converter is Or connected to a common local oscillation source via a frequency multiplier.

In particular, when the frequency converter has three or more stages and the number of frequency multipliers is two or more, the input terminal of each frequency multiplier is connected to a local oscillation input port of another frequency converter. Connect to the output end of the multiplier. Further, the local oscillation source is provided with a gold film as an output frequency variable means.

(Function) The microwave frequency conversion circuit with the above configuration obtains local oscillation input from multiple frequency converters by arbitrarily multiplying the common local oscillation leak by a frequency multiplier, so the local oscillation system is extremely simple. This configuration allows for small size and low cost. In addition, for example, since the transmitting (1i or receiving frequency bandwidth) is shared between each local oscillation system according to the respective multiplication orders, the operating frequency bandwidth required for the multiplier and local oscillation source can be narrower than in conventional circuits. This allows for a significant reduction in adjustment time.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows a first embodiment, in which the first local oscillation circuit 'kN1=1 of the first frequency converter 2, only the common local oscillation source 22 without a multiplier, and the second frequency converter 25 This is a double-conversion type transmission frequency conversion circuit in which the second local oscillation circuit is composed of an N multiplier 27 and a common local oscillation source 22.

First, the baseband signal frequency f1 is raised by the first local oscillation frequency 1) by the first frequency converter 21 to become an intermediate frequency (IP) ft. And engineering F
Obi BPF,? J suppresses unnecessary waves such as local oscillation leakage,
The signal is amplified to a predetermined level by the F-band amplifier 24. Next, the second frequency converter 25 raises only the local oscillation frequency NfL and converts it into the transmission frequency f, and the transmission BPF 26 suppresses unnecessary waves and sends it to a high-output amplifier, etc. (not shown). Output. The local oscillation circuit of the second frequency converter 25 has a multiplication order N of the common local oscillation source 22.
(N>2) multipliers 27 are connected.

The above frequency relationship is shown by the formula below. However, the first and second
It is assumed that the output frequency of the frequency converter is set to the upper sideband.
f, = f, ±Δfx 1N (fL soil △, l'L) = (
h+(1+N) f L )±(1+N)△fL Therefore, the variable setting bandwidth BWL of the local oscillator 22 and the multiplier 2
The output bandwidth BWM of 7 is as follows: BWL=SΔfs/(1+N) BWM=±NΔfs/(1+N). In other words, when the transmission frequency bandwidth Δf is the same, the local oscillator can be configured with a minimum of one piece compared to the conventional circuit shown in FIG. 6, and the variable setting bandwidth of the local oscillator and the multiplier are The output bandwidth is N/(1+N), respectively.
reduced to For example, when N=4, N
=3, the operating bandwidth is reduced to 75% of the conventional one.

FIG. 2 shows a second embodiment, which is a three-stage conversion type transmission frequency conversion circuit. 31, 35.

39 is a 1st, 2nd, and 3rd frequency converter, 32 is a local oscillator, and 37.38 is a multiplication order of N.

It is a multiplier of Ns (Nx, Ns>2). In addition, the BPF, amplifier, and transmission BPF of each intermediate frequency band are as follows:
This is omitted to simplify the explanation. The frequency relational expression is shown below.

f, ±△fx = f t tenf L±△fLf, ±△
fs=f Δft +Nw CfL±△fL
)” (f1+(1+N!) f L)±(1+N*
)△fLf4±△f+=fs±△f s 10N! N
s (f L±△fL)−(ft +(1+Nt +N
t Ns ) f ” )±(1+Nm 10Nt Ng
) Δ7L Therefore, the variable setting bandwidth B of the local oscillator 32
WL and the output bandwidth BWM of the multiplier 37.38.

BWM, BWL=±△f4/ (1+Nt +Nt Ns)B
WM Yi=±N2△J'4 / (1+Nt 10Nt N
s) BWM, 已±N, N, △f4/(1+N
t 10 Nt Ns). For example, N! =4, N5
=2, the local oscillator 32. The operating frequency bandwidths of the multipliers 37 and 38 are respectively 1/13°4/13 and 8/13 of the total transmission frequency bandwidth factor △f4, and N, =3,
When N, = 2, 1/10, 3/10, 6, respectively.
/10.

FIG. 3 shows a third embodiment, which is a three-stage conversion type transmission frequency conversion circuit. 41.45°49 is 1.2.
3 frequency converter, 42 local oscillator, 46.47.48
The multiplication orders are Nl r Nt + N, (
Ns to Ns>2). Note that the BPF, amplifier, and transmission BPF of each intermediate frequency band are omitted for the sake of simplification of explanation.

The frequency relational expression in this case is shown below.

f! ±Δf* = J'l +Na Cf L±△fL
) fs soil△fm=fxshi△f* 10Nt Cf L±
△fL)=f l +(Nt +Na) f L±(
Nl +Na)△fLf4±△f4=fs soil△fs
+Na Cf L±△fL)=f□+CNs +Na
10Ns) f L±("t +Nt1N,) ΔfL Therefore, the variable setting bandwidth BWL of the local oscillator 42 and the output bandwidth BWM of the multiplier 46, 47, 48.

BWM,, BWM, is, B W L = To △ / (Nl 10N! 10N3)
BWM, = ±N, △J'4 / (Nt +Na 1N
s ) BWM, = ±N, △f4/ (Nt + Na 10Nm) BWM, = Sat N, △b / (Nt 10Nt
+Na), and since the bandwidth is shared in accordance with the multiplication order of each multiplier, the adjustment time of the multipliers is shortened compared to the conventional circuit.

FIG. 4 shows an example of application of the present invention in which the multiplication order of each multiplier in FIG. 3 is set to 1, and a local system is constructed without any multipliers. In this case, from the above equation, the local oscillator 52
The variable setting bandwidth of the frequency converter and the local oscillation bandwidth of each frequency converter may be set to Δf4/3.

FIG. 5 shows a configuration in which the present invention is applied to a transmitter/receiver. 61.62 is the first and second frequency converter (up converter), 63 is a high output amplifier, 64 is a local oscillator, 65 is a local oscillation multiplier, 67.66 is the first and second frequency converter (down converter, 68 is a low noise amplifier,
69 is a duplexer, and 70 is an antenna.

In this embodiment, a common local oscillator 64 is used in a two-stage conversion type transmitting/receiving system, and when changing the transmitting/receiving frequency, the frequency of the local oscillator 64 is changed simultaneously. According to this configuration, the entire transmitting/receiving system requires only one local oscillator and multiplier, making it possible to significantly reduce the size and cost compared to conventional circuits.

Therefore, in the microwave frequency conversion circuit configured as in each of the above embodiments, a common local oscillator is connected directly to the local oscillator of each frequency converter or via a frequency multiplier for multi-stage conversion type frequency conversion circuits having two or more stages. Compared to conventional circuit configurations, the number of local oscillators can be minimized to one, and when setting the output or input frequency at the local oscillation frequency, the local oscillator The maximum variable setting bandwidth of each multiplier and the maximum operating frequency bandwidth of each multiplier can be reduced. This makes it possible to reduce the cost by reducing the external dimensions and shortening the adjustment time.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a microwave frequency conversion circuit that can minimize the number of local oscillators and reduce the local oscillation system bandwidth for selecting transmission or reception frequencies.

[Brief explanation of the drawing]

1 to 3 are configuration diagrams for explaining first to third embodiments of the microwave frequency conversion circuit according to the present invention, respectively, when configured as an up-converter, and FIGS. Figure 5 shows an application example of the microwave frequency conversion circuit of the present invention. Figure 4 is a configuration diagram when a multiplier is not used, Figure 5 is a configuration diagram when it is applied to a transmitter/receiver, and Figure 6. 1 is a diagram showing a configuration example of a conventional transmission frequency conversion circuit. 1.5, 21, 25, 31, 35, 39, 41j45,
49,51,55,59,61,62゜66.67...
・Frequency converter, 2, 7, 22, 32.42, 52.6
4...Local oscillator, 8.27°37.38.46,4
7.48.65...Frequency multiplier, 3,6,23.2
6... BPF, (,24... Intermediate frequency amplifier. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4

Claims (4)

[Claims] (1) A multistage microwave frequency conversion circuit having two or more stages of frequency converters, characterized in that local oscillation input ports of each frequency converter are connected to the same local oscillation source. circuit. (2) The microwave frequency conversion circuit according to claim (1), wherein some of the local oscillation input ports are connected to the same local oscillation source via a frequency multiplier. (3) The frequency converter has three or more stages, and the local oscillation input port of the second or higher stage frequency converter is connected to the local oscillation input port of the previous stage frequency converter via a frequency multiplier. A microwave frequency conversion circuit according to claim (1). (4) Claims (1) to (3) characterized in that the local oscillator has output frequency variable means.
The microwave frequency conversion circuit described in Section 1.