JPS5888907A - Transmission mixer - Google Patents

Abstract

PURPOSE:To remarkably decrease the local leakage, by cancelling the local leakage from a mixer through the summing of a signal adjusted with the phase of a local output. CONSTITUTION:An output of a local mixer 1'' is applied to a mixer 2'' via a directional coupler 7. The mixer 2'' mixes an output signal of an oscillator 1'' with an IF signal and outputs the result via a directional coupler 8. A part of the output signal of the oscillator 1'' appears directly as a transmission output not through the mixer 2''. Then, a part of the output signal of the oscillator 2'' is picked up from the directional coupler 7, the phase and amplitude are adjusted at a compensating circuit 9, and the result is summed with the transmission output via the directional coupler 8. The transmission of a leakage signal can not be performed by summing a signal having equal absolute value with the opposite phase for the leaked output of the local oscillator 1'', with equal absolute value.

Description

[Detailed Description of the Invention] The present invention uses a heterodyne system! This invention relates to a transmission mixer that can reduce the local leakage power of a transmission mixer to almost zero by adding a small and inexpensive circuit in a four-wave multiplex radio device.

Since the isolation of the transmission mixer must be at most 10, it is necessary to input the intermediate frequency PCM signal wave at a low level. Therefore, it is necessary to reduce the local leakage power in order to maintain the characteristics of the next stage amplifier, etc., in which the ratio of the signal wave power to the quadrature leakage power is small.

Therefore, in order to prevent local leakage, a band-elimination p-wave filter (hereinafter abbreviated as BEF), a circuit generator, or the like is used to reduce the local leakage power. However, in the case of the 16-phase alternating width modulation method or the case where the band is limited even in the 4-phase phase modulation method, it is necessary to reduce the local leakage power by about 40 db. A conventional transmission mixer in this case will be explained below.

FIG. 1 is a block diagram of a transmission mixer peripheral circuit in a conventional system using a BEF, and FIG. 2 is a block diagram of a transmission mixer peripheral circuit in a conventional system using a ↑·-curator and BEFt.

In the figure, 1 and 1' are local oscillators, 2 and 2' are transmitting oxers, and 3
, 3', 5.5' are isolators, 4.4' BE
F, 6- is a circulator.

In the case of Fig. 1, the intermediate frequency signal (IF signal) and the power from the local oscillation wIl are input to the transmission mixer 2, the intermediate frequency signal is converted into the desired radio station wave number signal, and the local leakage power is transmitted via the isolator 3 to the BEF 4. In order to reduce this and prevent reflection, the signal is sent to the next stage P-wave device etc. via the isolator 5. In this case, the local leakage power is approximately 4
BEF4 has the disadvantage that the circuit size is large and expensive in order to reduce the noise by 0 db.

In the case of Figure 2, the output of local oscillator 1/ is connected to Saki island
The intermediate frequency signal (IP flaw signal) is supplied to the image transmitter +2' via the transmitter +2' and is input to the transmitter +2'
The signal is converted into a radio station wave number signal at It is determined by the return loss of the input/output terminal of ' and the amount of isolation effect of each terminal of the circuit filter 6, and it is improved to about 25 db, but it is 4Qdb.
In order to suppress the local leak power of Fuku degree, it is about 1 more.
It decreases by about 5 db at B'EF4'. Therefore, the circulator 6 and the BEF 4' are required, resulting in a drawback that the circuit size is large and expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission oxer that can reduce the quadrature leakage power by 4 Qdb or more by adding a small and inexpensive circuit to eliminate the above-mentioned drawbacks.

In order to achieve the above object, the present invention extracts a part of the output of the local oscillator and uses a compensation circuit to adjust the amplitude and phase of the power so that the amplitude is adjusted by the local leakage power and the sending phase of the output of the transmitting oscillator. The embodiments of the present invention, which are characterized by being able to almost completely eliminate the local leakage power by equalizing and composing them, will be explained below according to the reasons.

FIG. 3 is a block diagram of a transmission oxer peripheral circuit according to an embodiment of the present invention.

In the figure, 1' is a local oscillator, z' is a transmission mixer, 3' is an isolator, 7.8 is a directional coupler, and 9 is a compensation circuit.

The output of the local oscillator 1' is branched by a directional coupler 7, one of which is input to a transmission mixer i and the other to a compensation circuit 9. In this case, the coupling degree of the directional coupler 7 with the compensation circuit 9 side is set to 10
If the elevation is set to db, the reduction in power to the transmitter 2' side will be slight. The compensation circuit 9 includes an amplifier, a variable attenuator, and a phase shifter.

The high frequency #i width of the local leak of the transmitting oxer 2 is expressed as AO(
'os(wt ψ), (AO is the maximum amplitude, W-
2πf1f is the frequency, φ is the phase) The output from the compensation circuit 9 is combined with the directional coupler 8, and AOCoBJwt
+ψ+(2n-1)π) (If the amplifier, variable attenuator, and phase shifter in the compensation circuit 9 are adjusted so that n is a positive integer, the amount of local leakage can be reduced to zero, not to mention attenuation of 4Qdb. It is also possible to approach the phase shift a1 as explained above.
, 84 microwave strip line or triplate line, etc. Therefore, the directional coupler 7° 8 and the compensation circuit 9 can be realized by integrated circuits, and can be realized at low cost and small size. - Transmission mixer 2 and The operation of isolator 3# is similar to that described in the conventional example.

FIG. ls4 is a block diagram of a transmitting mixer peripheral circuit according to another embodiment of the present invention.

In the figure, 1# is the local oscillator, ? is a transmission oxer, 3'# is a circulator, 8/ is a directional coupler, 10 is an in-phase hybrid circuit, and 11 is a circuit with the same local leakage power frequency characteristics as the transmission oxer 2#, for example - for an intermediate frequency signal. An oxer (hereinafter referred to as transmission mixer 11) having the same configuration as transmission mixer 2# without input, 9' is a compensation circuit.

Compensation circuit 9' is #! It has the same function as the compensation circuit 9 in the case of Fig. 3, but the difference from the case in Fig. 983 is the directional coupler 7.
Transmission mixer 1 using in-phase vibrid circuit 10 instead of 0
Add 1 for 9 points], send 4M < Kisa 11 and compensate (b)
The line 9 constitutes a compensation circuit.

! It uses multiple frequency bands within the same frequency band. In this case, transmit mixer 2#
The amplitude phase of the dilocal leak also differs somewhat depending on the ri frequency. In the circuit shown in Figure 3, a compensation circuit 90aI44& must be provided at the frequency used.

If the #A compensating subcircuit 9' is adjusted at the frequency at which the present circuit shown in FIG. For this purpose, the in-phase vibrid circuit 10 classifies the power of the local oscillator 1#, and one of them is used as a transmission mixer. 9 and the other to transmit mixer 11
・Transmission mixer 2# receives an intermediate frequency signal (ill'
(m number) is input and output power t- is obtained. Sending Miki?
11 is local leak detection without inputting an intermediate frequency signal.
shall be. As a result, if the output of the local oscillator l'' is set to 1/2 by 1/2 in the Frl phase bibrid l&il path lO, both the local leakage power from the transmitting mixer and the four-cal leakage power from the transmitting g1 mixer 11 will also change in amplitude phase. Even if the frequency of the local oscillator 1# rarely changes within the same frequency range, the effect is strong.
1llS in the diagram! 9 y mouth <Is it possible to connect the transmission mixer at the combining point of the directional coupler 8' rather than having the opposite phase? If the amplitude is adjusted so that the local leakage power of the transmitter mixer 11 is equal to the four-cal leakage power of the transmitter mixer 11, local leakage will occur over a wide band even if the frequency of the local oscillator 1# changes within the same frequency range. Power consumption can be reduced.

Incidentally, even if the in-phase vibrid circuit 10 does not reduce the output of the local oscillator 1#/ to 1/2, as long as the local leak frequency characteristics of the oscillator 11 do not change, the amplitude can be increased by the compensation circuit 9I. Alternatively, a close-coupled directional coupler may be used in place of the hybrid circuit 10. In this case as well, the compensation circuit consisting of the transmission mixer 11 and the compensation circuit 9', the in-phase bibrid circuit 10, and the directional coupling @g/ can be realized as an integrated circuit at a low cost and in a small size.

As described above in ##11, the present invention has the fruit of providing a transmitting mixer that can greatly reduce the local leakage power of the transmitting mixer by adding a small and inexpensive circuit.

[Brief explanation of drawings]

Figure 1 is a block diagram of a transmission mixer peripheral circuit in a conventional system using a BEF, Figure 2 is a block diagram of a transmission mixer peripheral circuit in a conventional system using a circulator and BEF, and Figure 3 is a block diagram of the transmission mixer peripheral circuit in a conventional system using a circulator and BEF. Figure #g4 is a block diagram of the transmission mixer peripheral circuit of another embodiment of the invention. 1 in the figure. 1', l'l 1'' is a local oscillator, 2
．． 2', 2'. 2′l is a transmission mixer, 3.3′, 3′, 3”,
5.5' is an isolator, 4.4' is a BEF16 circulator, 7, 8.8' are directional couplers, 9.9'
is a compensation circuit, 10. ? /Figure IF times signal P2 figure p figure fFfPro

Claims (1)

[Claims] 1. In a heterodyne microphone α-wave multiplexing radio device, a first distributor is provided on the input terminal side of a local oscillator of a transmission mixer to distribute the output of the local oscillator. a compensation circuit that inputs the output of one to the transmission mixer and compensates for the phase and amplitude of the high-frequency power of the other output, and a second combiner that combines the output of the compensation circuit and the output of the scissor transmission mixer; 1. A transmission mixer characterized in that the compensation circuit is set so as to have an opposite phase and an equal amplitude with respect to local leakage power of the transmission mixer. 2. In claim 1, the compensation circuit consists of a circuit with the same frequency characteristics as the local leakage power of the oscilloscope transmitter and a circuit that compensates for the phase and amplitude of the high frequency power. A transmission mixer with a characteristic.