JPS61105914A - Mixer circuit - Google Patents

Abstract

PURPOSE:To suppress sufficiently any of a couple of input signals at an output terminal to a small value by connecting a double pair differential amplifier circuit to the output terminal of each amplifie circuit so as to cancel the leakage component in order to obtain a large separation between a couple of input signal terminals. CONSTITUTION:GaAs-FETs116-119 forming the double pair differential amplifier circuits give an output of a GaAs-FET110 to a load resistor 120 or 121 according to the polarity of a control voltage given to a gate to switch the two modes of the output of a GaAs-FET111. The 2nd frequency signal fed to an input terminal 103 is amplified by the GaAs-FET113, 114 forming the differential amplifier circuit to apply switch control to the output of the GaAs- FET116-119 forming the double pair differential amplifier circuits. The signal fed to the 1st and 2nd signal input terminals 102, 103 is fed to the GaAs-FET 116-119 forming the double pair differential circuits while being balanced, then the crosstalk to output terminals 106, 107 is less.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a circuit configuration of a mixer circuit that converts microwave band signal frequencies and numbers.

(Prior art) In low frequency bands, differential amplifier circuits are constructed using bipolar transistors, but in this case, the pace amplifier is used to improve the nonlinearity of the voltage vs. current characteristics between the vines. As shown in FIG. 3, a bipolar transistor 351. δ5
It is necessary to add series resistors 35 and 354 to the second step, respectively. The deterioration of the noise figure due to these resistors 353 and 354, combined with the fact that the bipolar transistor has a higher noise figure than the GaAs-FET in the microwave band, makes it difficult to create a practical microwave band mixer. It was made up of bipolar transistors.

On the other hand, GaAs-FETs have long been used in amplifiers and mixers as devices that can obtain high gain in the microwave band. An example of a mixer using QaAs-FET is shown in FIG.
FETs were used to generate a signal with the frequency of the sum or difference of a pair of input signals by utilizing distortion characteristics. In FIG. 4, 401 is a drain power supply terminal, 402 and 403 are signal input terminals, 406 is a signal output terminal, and 450
is a GaA1-FET, and 431 is a load resistor.

(Problems to be Solved by the Invention) The configuration described above suffers from the drawbacks of lack of isolation between the pair of input signals and the lack of separation between the pair of input signals due to the presence of eight different frequencies in a single device. There was a drawback that part of the input signal was output to the terminal.

In addition, in conventional mixers, when a correction circuit is added to correct the local oscillation signal flowing to the output terminal, the transmission output generated by mixing the local oscillation signal with the intermediate frequency signal also leaks to the local oscillation side terminal. Therefore, this signal passes through the correction circuit and is sent to the output terminal. Since the delay time between this leakage output and the output of the normal signal is significantly different, echo distortion often occurs in the transmission characteristics.

An object of the present invention is to connect a pair of differential amplifier circuits to the output terminals of each amplifier circuit so as to cancel out the leakage components. The object of the present invention is to provide a filter circuit using QaA s-FET, which eliminates the drawbacks and is configured such that both of the above-mentioned pair of input signals can be suppressed to a sufficiently low level at the output terminal.

(Means for solving the problem) The mixer circuit according to the present invention is Q a A s -N E
It consists of first to first Oth GaAs-FETs and first and 112th resistors.

The sources of the first and second GaAs-FETs are commonly connected, and the first resistor is connected to the common source connection point.

The eighth GaAs-NET is the second Q a As -F
The gate is connected to the gate of the ET, and the source is connected to a common source connection point between the first and second QAs-NET and the first resistor.

Connect one end of resistor #1 to the source common ground point,
The other end is connected to the ground potential point.

The fourth and fifth GaAs-FETs are connected to the drain of the first GaAs-FET.
is connected.

The sixth GaAs-FET is the second (7') GaAs-FET.
Connect the Sonis to the drain of the FET and connect the fifth GaAs-
Connect the gate to the gate of the FET, and connect the fourth G a A
The drain is connected to the drain of s-FET.

The seventh QaAs-FET is the second GaA
Connect the source to the drain of the s-FET and connect the fourth QaA
Connect the gate to the gate of s-FET and connect the fifth Q
The drain is connected to the drain of aAs-FET.

The eighth GaAs-FET has its source connected to the second resistor, and its drain connected to the gates of the fifth and sixth GaAs-FETs.

The ninth GaAs-FET is the eighth Q & Al1-FET
The source is connected to the source and the second resistor, and the drain is connected to the gates of the fourth and seventh GaAs-FETs.

The second resistor is connected between the sources of the eighth and ninth GaAs-FETs and the ground potential point.

The tenth GaAs-FET has its gate connected to the gates of the eighth and ninth QaAs-FgTs, and connects the sources of the eighth and ninth GaAs-FETs and the gates of the eighth and ninth QaAs-FgTs. The source is connected to the common connection point of the two resistors.

In the above configuration 2, the present invention provides w, 1 and 8th GaA
A high frequency signal of a first frequency is applied from the gate common connection point of the s-FET, a high frequency signal of the second frequency is added from the gate common connection point of the ninth and tenth GaAs-FETs, and a high frequency signal of the second frequency is applied from the gate common connection point of the ninth and tenth GaAs-FETs. Ga A s - N ET drain common connection point or fifth and seventh Q a A
The configuration is such that a third high frequency signal having a frequency that is the sum or difference of the high frequency signals of 81 and the second frequency can be taken out from the drain common connection point of s-NET.

(Example) Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of an i-fusa circuit according to the present invention. In FIG. 1, 101 is a power supply terminal;
02 is an input terminal for the first frequency signal, 10 is an input terminal for the second frequency signal, 106 and 107 are signal output terminals, 104 and 105 are bias terminals,
110 to 119 are GaAs-FETs, 120 to 119 are respectively GaAs-FETs,
126 are resistors, respectively. A pair of GaAs-FE
T110 and T111 are differential amplification circuits for the first frequency signal, and an output in reverse phase is obtained on the drain side of the GaAs-FET1tO, and an output in positive phase is obtained on the drain side of the GaAs-FET111. The GaAs-FETs 116 to 119 forming the dual differential amplifier circuit are GaAs-FETs according to the polarity of the suppressing am pressure applied to the gates.
Connect the output of 110 to the load resistor 120 to connect the GaAs-
Connect the output of FET 111 to load resistor 121, or
Alternatively, connect the output of GaAs-FET 110 to load resistor 1
21 and the output of the GaAs-FET 111 is connected to the load resistor 120. The second frequency signal applied to the input terminal 106 is applied to a GaAs-FET forming a differential amplifier circuit.
11 and 114 to control switching of the outputs of QaA8-FETs 116 to 119 forming a dual differential amplifier circuit. @1 and second signal input terminal 10
Since the signals applied to 2.106 are balanced together and applied to the GaAs-FETs 116 to 119 forming a dual differential circuit, there is little leakage to the output terminals 106 and 107. Generally, if the value of resistor 125 is small, GaAs-FET
In the differential amplifier circuit based on 110 and 111, GaAs-
The positive phase output appearing at the drain of FET111 is Ga
It tends to be lower than the reverse phase output appearing at the drain of A s -F ET110. In such a case, the balance of the signals applied to the dual differential amplifier circuits 116 to 119 will be degraded, and this will also cause leakage to the output terminals 106 and 107.

In the present invention, a GaAs-FET 112't- is added, and the signal on the positive phase side of the first frequency applied to the input terminal 102 is corrected by a resistor 125.
Since the signal is output to the drain of the signal, it is possible to prevent deterioration of balance due to a drop in the level on the positive phase side, which tends to occur in differential amplifier circuits using GaAs-FETs. GaAs-FETI 1 forming a differential amplifier circuit that amplifies the second frequency
A GaAs-FET 115 is also added to the 3°114 to improve balance. GaAs-FET
The differential amplifier circuit consisting of 116 to 115 not only improves an unbalanced signal to a balanced signal, but also amplifies the second frequency signal and forms a dual differential amplifier circuit.
It also works to prevent the signals present at T 116 to 119 from leaking to the input terminal 106. Even when viewed from the input terminal 102, the differential amplifier circuit consisting of GaAs-FETs 110 to 112 has a buffer effect, although it is not as strong as when viewed from the input terminal 10. It works to prevent existing signals from leaking out.

As shown in FIG. 1, by inputting a local oscillation signal through input terminal 103 and adding a high frequency signal through input terminal 102, the cross-modulation characteristics of the high frequency signal can be improved. In FIG. 1, by inserting a resistor 124 and increasing the local oscillation signal level to be applied to the input terminal 10,
- The waveform during the switching operation of the FETs 116 to 119 can be made rectangular, and the cross modulation characteristics of high frequency signals can be further improved. Further, it is assumed that the mixer circuit according to the present invention receives a local oscillation signal from an input terminal 103, receives an intermediate frequency signal from an input terminal 102, and obtains an output from an output terminal 106 or an output terminal 107. By adding a compensation circuit with variable phase and level between the output terminals 106, 107 and the input terminal 10, the cross-modulation characteristics of the transmission signal are excellent, and the leakage of local oscillation signals to the output terminals 106, 107 is prevented. A transmission mixer with low thermal noise is constructed.

FIG. 2 is a block diagram showing a frequency converter according to an example of application of such a circuit. In Figure 2, 24
2 is an intermediate frequency amplification circuit, 241 is an input terminal for intermediate frequency signals, 243 is a local oscillation circuit, 247 is a mixer circuit shown in Fig. 111, 245° and 246 are correction circuits that can vary the phase and level, respectively; The semi-fixed inductance 246 is a semi-fixed resistor. In order to improve the cross-modulation characteristics of the transmission characteristics, the level of the intermediate frequency signal is sufficiently reduced and used within a small signal level range with good linearity. In such a case, the local oscillation level becomes relatively high, and even if the mixer circuit has excellent balance characteristics, the amount of leakage of the local oscillation signal at the output terminal becomes noticeable. In order to correct this, a correction circuit consisting of an inductor 45 and a resistor 46 is provided, and correction is made at the same level and in opposite phase to the local oscillation signal present at the output terminal, thereby further reducing the amount of leakage of the local oscillation signal. be able to.

In the case of Fig. 2, the input terminal 20 to which the local oscillation signal is applied
On the other hand, the differential amplifier circuit composed of GaAs-FETs operates as a buffer amplifier, and the level of the transmitted signal leaking toward the local oscillation circuit is sufficiently small, so that the echo distortion described above becomes sufficiently small. .

(Effects of the Invention) As explained above, in the present invention, in order to obtain a large degree of separation between a pair of input signal terminals, a pair of differential amplifier circuits is installed at the output terminal of each amplifier circuit so that leakage components are mutually canceled out. By connecting it to , the balance is improved and even-order cross-modulation distortion is reduced. Furthermore, since each Q a A s -FET is a DC direct-coupled type, it is suitable for a monolithic IC, and has the effect of easily achieving high reliability in addition to miniaturization.

Furthermore, in the present invention, since the source series resistance is omitted by using a GaAs-FET, noise generation is small, and even if the intermediate frequency signal level is reduced to improve the cross-modulation characteristics of the transmission characteristics, the noise is not included in the output terminal. Thermal noise and local oscillation signal level caused by this can be kept sufficiently low.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a mixer circuit according to the present invention. FIG. 2 is a block diagram showing an embodiment of a frequency conversion device to which the mixer circuit shown in FIG. 1 is applied. FIG. 8 is a circuit principle diagram illustrating an example of a differential amplifier circuit constructed using a conventional technique using bipolar transistors. FIG. 4 shows Q a A s -FE according to the prior art.
This is a circuit diagram showing an example of a mixer circuit using T. 110-119, 430 ・GaAs-FET1
20-126,246,351. φ52゜431...
・Resistor ro 51,352 book ・Bipolar transistor 242・
...Intermediate frequency amplification circuit 243...Local oscillation circuit 245@spring-e-inductor 247...Fusa circuit 101-107, 202, 203, 206°207.2
41,244.401~403゜406... end
Child patent originator: NEC Co., Ltd. agent, patent attorney: Hisao Inoro) Figure 2

Claims (1)

[Claims] First and second GaAs-FEs whose sources are commonly connected
T, and a third GaAs-FE whose gate is connected to the gate of the first GaAs-FET and whose source is connected to a common source connection point of the first and second GaAs-FETs.
T, a first resistor connected between the source common connection point and the ground potential point, and fourth and fifth GaAs-FETs whose sources are connected to the drain of the first GaAs-FET.
FET, and a sixth GaAs-FET having a source connected to the drain of the second GaAs-FET, a gate connected to the gate of the fifth GaAs-FET, and a drain connected to the drain of the fourth GaAs-FET. a GaAs-FET, a source connected to the drain of the second GaAs-FET, a gate connected to the gate of the fourth GaAs-FET, and a drain connected to the drain of the fifth GaAs-FET; 7 GaAs-FET, an eighth GaAs-FET whose drains are connected to the gates of the fifth and sixth GaAs-FETs, and the eighth GaAs-FET.
T and the source of the fourth and seventh G
9th G whose drain is connected to the gate of aAs-FET
aAs-FET and the eighth and ninth GaAs-FETs
a second resistor connected between the source of the ET and a ground potential point; and a gate connected to the gates of the eighth and ninth GaAs-FETs;
a tenth GaAs-FET whose source is connected to a common connection point between the source of the ET and the second resistor; A high frequency signal is applied, and a second
a high frequency signal with a frequency of
aAs-FET drain common connection point or the fifth
and a third high-frequency signal having a frequency that is the sum or difference of the high-frequency signals of the first and second frequencies from the common drain connection point of the seventh GaAs-FET. Misa circuit.