JPH0453083Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The invention uses a double balanced mixer configured to output a high-frequency signal with its phase reversed by 180° by reversing the polarity of the applied bias. Regarding phase circuits.

[Conventional technology]

FIG. 3 is a diagram showing a conventional example of a phase circuit using a double balanced mixer.

As a phase circuit using a double balanced mixer, as shown in Fig. 3a, coils L1 to L6,
Consists of diodes D1 to D4, bias power supply _VB , and switch SW, and outputs high frequency output signals.
There is one that can be flipped 180 degrees. This is done by supplying a high frequency signal to the coil L1 and controlling the phase by inverting the polarity of the bias power supply _VB with the switch SW, so that a signal inverted by 180° can be extracted from the coil L6 as shown in Figure 3b. This is what I did. Therefore, coils L2 and L3 are electromagnetically coupled to coil L1 on the input side, and coil L on the output side.
Coils L4 and L5 electromagnetically coupled to 6 are connected in series in the same polarity direction, and diodes D1 to 6 with reversed polarity are connected between both ends of the series circuit.
D4 is connected, and a bias circuit consisting of a bias power supply _VB and a switch SW is connected between the series connection point of coils L2 and L3 and the series connection point of coils L4 and L5. Therefore, by switching the switch SW, the direction of the current flowing through the coils L2 to L5 of the double balanced mixer can be changed, and the phase of the signal passing through the double balanced mixer can be changed by 180 degrees.

[The problem that the idea aims to solve]

However, with the conventional phase circuit using the double balanced mixer shown in Figure 3 above, a complete 180° phase signal cannot be obtained due to variations in the diodes and coils that make up the circuit, and when switching The problem is that the level changes and selection at the component level is also quite difficult.

In recent years, NMR (nuclear magnetic resonance) devices have adopted pulse techniques consisting of complex pulse sequences, for example when decoupling carbon and hydrogen nuclei. It will be done. If a phase circuit using the above-mentioned double balanced mixer is used for such NMR analysis, there will be a shift in the phase and a poor S/N ratio due to fluctuations in the signal level.
There is a problem that the accuracy of analysis deteriorates.

The present invention solves the above problems, and aims to provide a phase circuit using a double balanced mixer that can eliminate phase shifts and signal level fluctuations.

[Means to solve the problem]

Therefore, the present invention uses a phase circuit using a double balanced mixer configured to invert the phase of a high-frequency signal by 180 degrees and output it by reversing the polarity of the applied bias. Insert and connect parallel circuits in series, and connect parallel circuits of diodes and capacitors in series to each of the output side coils of the pair to which the bias circuit is connected.
It is characterized by using a variable capacitor for one of the capacitors.

[Effect]

In the phase circuit using the double balanced mixer of the present invention, a parallel circuit consisting of a diode and a variable resistor is inserted and connected in series in the bias circuit, so by adjusting this variable resistor, either the 180° inverted signal The level of one of the signals can be changed, thereby eliminating level fluctuations. In addition, a parallel circuit of a diode and a capacitor was inserted and connected in series to each of the pair of output coils to which the bias circuit is connected, and a variable capacitor was used as one of the capacitors, so by adjusting the capacitance of the variable capacitor, It is possible to eliminate the 180° inversion phase shift.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of a phase circuit using a double balanced mixer according to the present invention, and FIG. 2 is a diagram for explaining the operation of the phase adjustment circuit. In the figure, L1 to L6 are coils, D1 to D8
is a diode, R1 to R4 are resistors, C1 and C2 are capacitors, _VB is a bias power supply, and SW is a switch.

In the example shown in Figure 1, the basic configuration of a phase circuit using a double balanced mixer is between the series connection points of series connection coils L2 and L3 on the input side and series connection coils L4 and L5 on the output side. A bias circuit consisting of a bias power supply _VB and a switch SW is connected to the bias circuit, and a parallel circuit consisting of a resistor R1 and a diode D5 and a parallel circuit consisting of a resistor R2 and a diode D6 are connected to this bias circuit as a signal level adjustment circuit. The diodes D5 and D6 are inserted and connected in series in opposite directions. Then, one of the resistors R1 and R2, R1
By using a variable resistor in both, the magnitude of one of the currents can be adjusted. In addition, as a phase adjustment circuit, a parallel circuit consisting of a capacitor C1, a resistor R3, and a diode D7 is connected to the series-connected coils L4 and L5 on the output side, and a parallel circuit consisting of a capacitor C2 and a resistor R
4 and a diode D8 are inserted and connected in series so that the diodes D7 and D8 are in opposite directions. And capacitor C
By using a variable capacitor for one of C2 and C2, one phase can be adjusted.

With the above configuration, level changes due to phase switching can be eliminated by adjusting the resistor R1 and making the currents i1 and i2 the same. That is, current i1 flows through resistor R1 and diode D6, whereas current i2 flows through resistor R2 and diode D5, so by setting the resistance value of resistor R1, current i1 becomes the same as current i2. It can be adjusted as follows.

Moreover, when the switch SW is switched to change the phase by 180 degrees, the current i1 is switched to the current i2, and the circuit changes from a to b in FIG. 2. Therefore, fine adjustment of the phase is possible by setting the capacitance of capacitor C2 in Figure b, and perfect adjustment is possible.
Since it is possible to set a 180° inverted phase, it is possible to eliminate phase shifts caused by phase switching.

Note that the present invention is not limited to the above-described embodiments, and various modifications are possible. In the above embodiment, two sets of parallel circuits each consisting of a diode and a resistor are connected as a level adjustment circuit with the diodes facing in opposite directions.
If the bidirectional current can be adjusted independently, 1
It may also be configured with only a set of parallel circuits. For example, a resistor may be connected in series with a diode. The same applies to the phase adjustment circuit, and the position opposite to the series connection point of coils L4 and L5, that is, the diode D
It may also be connected to the 1 to D4 sides.

[Effect of idea]

As is clear from the above explanation, according to the present invention, it is only necessary to insert and connect a parallel circuit of a diode, a resistor, and a capacitor in series. It is possible to obtain the output of a high frequency signal.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of one embodiment of a phase circuit using a double balanced mixer according to the present invention, Fig. 2 is a diagram for explaining the operation of the phase adjustment circuit, and Fig. 3 is a diagram showing the configuration of an embodiment of a phase circuit using a double balanced mixer according to the present invention. 1 is a diagram showing a conventional example of a phase circuit using a mixer. L1-L6...Coil, D1-D8...Diode, R1-R4...Resistor, C1 and C2...Capacitor, _VB ...Bias power supply, SW...Switch.

Claims (1)

[Scope of utility model registration request] In a phase circuit using a double balanced mixer configured to invert the phase of a high-frequency signal by 180° and output it by reversing the polarity of the applied bias, a parallel circuit of a diode and a variable resistor is connected in series to the bias circuit. A double balance device is characterized in that a parallel circuit of a diode and a capacitor is inserted and connected in series to each of the output side coils of the pair to which the bias circuit is connected, and a variable capacitor is used as one of the capacitors. A phase circuit using a domixer.