JPH03219712A - Balanced type mixer - Google Patents

Abstract

PURPOSE:To attain the use of a local oscillation signal oscillator with a small output by applying a bias to two diodes being components of a mixer so as to decrease the local oscillation signal inputted to a local oscillation signal. CONSTITUTION:An LO signal is inputted to a local oscillation LO signal terminal 2 and an RF signal is inputted to an RF signal terminal 1, then the IF signal subject to frequency conversion obtained by the mixture of the signals is obtained from an IF signal terminal 3. Then a bias voltage is applied from a bias terminal 4 to diodes X1, X2 and the voltage is set so that the conversion loss of the mixers is minimized. The bias voltage is not outputted to an IF terminal 3 by an IF DC branch line 9. Thus, the bias voltage is applied to the diodes X1, X2 to decrease the LO signal inputted to the LO terminal 2 thereby attaining the use of a small output of LO oscillator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mixer used in a microwave band, and more particularly to a balanced mixer using a rat race type hybrid.

[Conventional technology]

Conventionally, a balanced mixer composed of a rat race type hybrid and a diode used in the microwave band is constructed as shown in FIG. In the figure, of the four terminals of the rat race type hybrid 5, two terminals with isolation are provided with a radio frequency (RF) signal terminal 1 and a local oscillator (LO) signal terminal 2, and the remaining two terminals are terminal and R
Diodes Xi and X2 are connected with opposite polarities to the open-end line 6 for shorting the F-LO signal.

An intermediate frequency (IF) signal terminal 3 is connected to this open-ended line 6.

Note that an IF return 10 is connected to the LO signal terminal 2.

[Problem to be solved by the invention]

The conventional balanced mixer described above has diodes Xi,
Since X2 is connected with opposite polarity via the open-ended line 6, and the IF signal terminal 3 is connected to this open-ended line 6, these diodes XI.

Cannot bias X2. For this reason, L
There is a problem in that it is necessary to increase the LO multiplied signal input from the O signal terminal 2, and an LO signal oscillator with a large output must be used.

An object of the present invention is to provide a balanced mixer that makes it possible to use a low output LO signal oscillator.

[Means to solve the problem]

The balanced mixer of the present invention connects an RF signal terminal and an LO signal terminal to two terminals having rat race type hybrid isolation, respectively, and connects the other two terminals to an open-ended line for high frequency short circuit. A mixer with two diodes connected with opposite polarities between them, a DC return and a DC blocking capacitor inserted between one of the diodes and an open-ended line, and an I connected to the open-ended line.
The configuration is such that the IF signal terminal and bias terminal are connected via an F-DC branching filter.

[Effect]

According to the present invention, it is possible to apply a bias to two diodes, and it is possible to reduce the output of the LO multiplied signal input to the LO signal terminal.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. In the figure, the rat race type hybrid 5 is formed on a dielectric substrate (not shown), and out of its four terminals, two terminals with isolation are connected to DC blocking capacitors C1 and C2, respectively. RF signal terminal 1. LO signal terminal 2 is connected. In addition, the terminal on this LO signal terminal 2 side has an I F which is composed of a capacitor and an inductance.
IJ turn 7 is connected. On the other hand, diodes Xi and X2 are connected with opposite polarities between the remaining two terminals and the open-end line 6 for RF-LO short circuit.

In this case, a DC return 8 and a DC blocking capacitor C3 are inserted between one of the diodes X1 and the open-ended line 6. DC return 8 is composed of an inductance.

Furthermore, one signal line 6a is connected to the open-end line 6, and an I
The F terminal 3 and bias terminal 4 are connected to each other. This IF-DC branching filter 9 is composed of a capacitor and an inductance.

According to this configuration, by inputting an LO multiplied signal to the LO signal terminal 2 and an RF signal to the RF signal terminal 1, the frequency-converted IF multiplied signal obtained by mixing these signals,
It can be obtained from the IF signal terminal 3. At this time, a bias voltage is applied to the diodes X1 and X2 from the bias terminal 4, and this voltage is set so that the conversion loss of the mixer is minimized (10 voltages in this example).
.

This bias voltage is not outputted to the IP terminal 3 by the IF-DC branching filter 9.

Therefore, this bias voltage is applied to diode XI.

By applying to X2, L is input to LO terminal 2.
It becomes possible to make the signal O times smaller, and it becomes possible to use a small output LO oscillator.

In addition, since the IF signal terminal 3 and the bias terminal 4 are taken out from the open end line, in other words, the mixer, by a single common line 6a, the IF-DC branching filter 9 is configured to be attached outside the mixer. For example, when the mixer is mounted in a package with a pin terminal, one pin terminal corresponding to the wire 6a may be made to protrude outside the package. Therefore, in this type of mixer, input and output of the IF multiplied signal bias voltage can be performed with one pin terminal, and the same package as in the case of a mixer without bias can be used.

When using this mixer as a transmission mixer, input the LO multiplied signal to the LO signal terminal 2, and input the LO multiplied signal to the IF signal terminal 3.
By inputting the IF multiplied signal to the RF signal terminal 1, the RF
I can get a signal.

Further, the RF signal terminal 1 and the LO signal terminal 2 can be exchanged with each other.

〔Effect of the invention〕

As explained above, in the present invention, since bias can be applied to the two diodes constituting the mixer, L
The LO signal input to the O signal terminal can be made small, and a small output LO signal oscillator can be used. Also, IF-D
By attaching a C branching filter externally, it is also possible to input/output the IF multiplied signal and apply a bias voltage using one pin terminal of the packaged mixer.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional balanced mixer. 1...RF signal terminal, 2...LO signal terminal, 3...
・IF signal terminal, 4... Bias terminal, 5... Rat race type hybrid, 7 lead, 6... Open end line, 7
...IF return, 8...DC return, 9...
IF-DC branching filter, 10...IF return, XI, X
2...Diode, CI, C2, C3...DC blocking capacitor. (Ir)

Claims (1)

[Claims] 1. A rat race hybrid formed on a dielectric substrate, and 2.
a high frequency signal terminal and a local signal terminal respectively connected to the terminals of the hybrid, and two diodes connected with opposite polarities between the other two terminals of the hybrid and the open-ended line for high frequency short circuit, respectively; A DC return and DC blocking capacitor inserted between one of these diodes and the open-ended line, an intermediate frequency/DC splitter connected to the open-ended line, and an intermediate frequency/DC splitter connected to the splitter, respectively. A balanced mixer characterized by having a signal terminal and a bias terminal.