JPH012411A - frequency converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a frequency conversion device that can be used in broadcast receivers, communication devices, and the like.

Conventional technology - Conventionally, receivers used for terrestrial broadcasting, especially CATV, satellite broadcasting, and satellite communications, have two frequency converters in order to receive incoming weak signals with high sensitivity and with low distortion. A double-balanced mixer, which is often a double-balanced mixer, uses four diodes or transistors connected in a ring shape, switches with a local oscillation signal necessary for frequency conversion, and converts the received high-frequency signal into an intermediate signal. This is a circuit that converts it into a frequency signal. Regarding this, see, for example, “Sato et al., 64.
Channel CATv UP/DOWN Converter: National Technical Report (National Te
Chnical Report), Vol. 30, No. 1, FEB, 1984J, ``Japanese Patent Application Laid-Open No. 135634/1983''.

Hereinafter, while referring to the drawings, the conventional frequency change described above will be explained.
II! The device will be explained. Fig. 3 is a circuit diagram of a conventional frequency converter, in which the local oscillation signal input from terminal 1 is input to an unbalanced/balanced converter 2 composed of a spectacle-shaped balloon.
After converting the signal into a balanced signal, the signal is supplied to the gate electrode of a double balanced mixer composed of electric field Tsurusu transistors (hereinafter referred to as FETs). The balanced signal is supplied so that FET8.1) and FET9,10 are switched alternately, and in order for FET8.9,10.1) to be sufficiently conductive and non-conductive, the local oscillation signal must be +1.0 d B m or more is required. Here, the gate bias voltage of the FET 8.9.10.1) is supplied from the terminal 7 via the resistor 23 to the gate electrodes of the FE78,1) and the FE79.1) by the unbalanced/balanced converter 2. ing.

On the other hand, the high frequency signal is sent from the terminal 13 to the unbalanced/balanced converter 1.
2, the signal is converted into a balanced signal, and then supplied to the source electrode of the FET constituting the double balanced mixer. In the double-balanced mixer, a high frequency signal is switched using a local oscillation signal injected from the gate electrode, and a balanced intermediate frequency signal is taken out from the drain electrode of the FET.The balanced intermediate frequency signal is converted into a balanced/unbalanced converter. At step 14, the signal is converted into an unbalanced signal, taken out from terminal 18, and supplied to the next stage. Terminal 17 supplies power to an FET that configures a double-balanced mixer.
current is flowing through. Capacitor 15.3 is for high frequency grounding.

Problems to be Solved by the Invention However, in the above configuration, the FETs constituting the double-balanced mixer simply operate as "switches", so that the local oscillation signal supplied to the gate electrode and the local oscillation signal from the power supply terminal are As a result, the input impedance of the gate electrode varies depending on the frequency, so the voltage value generated at the gate electrode varies depending on the frequency, causing a difference in the current flowing through the FET.

The present invention has been made in view of the above problems, and enables a constant injection of local oscillation signals regardless of frequency.
The object of the present invention is to provide a frequency conversion device for a double-balanced mixer that maintains constant current consumption without deteriorating high frequency performance.

Means for Solving the Problems In order to solve the above problems, the frequency converter of the present invention connects two passive elements in series between the gate electrodes of FETs constituting a double balanced mixer. The bias voltage of the gate electrode is supplied from the connection point, and even if the input impedance of the FET gate changes for local oscillation signals, the impedance seen from the local oscillator side does not change much due to the passive element and remains almost constant. It has a configuration in which a voltage is applied to the gate electrode and a constant current flows through the FET.・Effect
- With the above-described configuration, the present invention makes it possible to keep the current consumption of the double-balanced duck mixer constant and keep the high frequency performance of the frequency converter constant over a wide band.

Embodiment Hereinafter, a frequency conversion device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the first embodiment of the present invention.
1 shows a circuit diagram of a frequency conversion device according to an embodiment of the present invention.

The local oscillation signal input from terminal l is converted into a balanced signal by unbalanced/balanced converter 2, and is supplied to the gate electrode of FET 8゜9.10.1) that constitutes a double balanced mixer. . Furthermore, the gate electrodes of IIT8.1) and FET9.1G are connected, and a resistor 5 and a resistor 6 are connected in series between the gate electrode of FE78.1) and the gate electrode of FET9.10, The gate bias voltage to be applied to the gate electrode is connected to the connection point of the resistor 5゜6 through the terminal 7.
supply more. On the other hand, the high frequency signal enters the unbalanced/balanced converter 12 from the terminal 13, and after being converted into a balanced signal,
It is supplied to the source electrode of said FE78.9.10.1).

The local oscillation signal and the high frequency signal are mixed in the double balanced mixer, and an intermediate frequency signal is generated from the drain electrode of the FET 8.9.10.1), and the balanced/unbalanced converter 14 is generated.
The signal is then converted into an unbalanced signal and taken out from the terminal 18.

In addition, a balanced/unbalanced converter 14 and an unbalanced/balanced converter 2
, 12 may be a spectacle-type balun or a differential amplifier, etc.
Capacitors 3, 4, and 15 are for high frequency grounding, and coil 16 is a choke coil. With this configuration, the amplitude of the local oscillation signal is made constant within the oscillation band by the resistor 5.6, the current consumption becomes constant, and wide band performance can be realized.

FIG. 3 shows a circuit diagram of a frequency conversion device according to a second embodiment of the present invention. The local oscillation signal input from terminal 1 is converted into a balanced signal by unbalanced/balanced converter 2, and FET8, 9, 10.1) which constitutes a double balanced mixer.
is supplied to the gate electrode. Furthermore, FET8,1)
and the gate electrode of FET9゜10 are connected, and the FET
Between the gate electrode of ET8゜ll and the gate electrode of said FE79.10, a resistor 5 and a diode 19.
21 and the parallel connection of the resistor 6 and diodes 20.22 having opposite directions are connected in series, and the cathode electrode of the diode 19.20 and the diode 21.22 are connected to the connection point of the resistor 5.6. An anode electrode is connected thereto, and a gate bias voltage to be applied to the gate electrode is supplied from the terminal 7 to the connection point. On the other hand, the high frequency signal enters the unbalanced/balanced converter 12 from the terminal 13, converts it into a balanced signal, and then passes through the FETs 8, 9, 10 .・1)
is supplied to the source electrode of The knee balanced type
- The local oscillation signal and the high frequency signal are mixed in the mixer, and an intermediate frequency signal is generated from the drain electrodes of the FETs 8.9, 10.1), which is converted into an unbalanced signal by the balanced/unbalanced converter 14, and is converted to a terminal 18. taken out from Further, the balanced/unbalanced converter 14 and the unbalanced/balanced converter 2.12 may be glasses-type baluns or differential amplifiers, etc., the capacitor 3.4.15 is for high frequency grounding, and the coil 16 is a choke coil. . With this configuration, the local oscillation signal is transmitted through the diode 19. 20. By generating a forward voltage of 21.22, the amplitude within the oscillation band becomes constant, current consumption becomes constant, and wide band performance can be realized.

FIG. 4 shows a conventional example of a frequency converter and a seventh embodiment of the present invention.
J, shows a diagram of the flow characteristics. The horizontal axis represents the frequency of the high-frequency signal, and the vertical axis represents the drain current representing the current consumption of the double-balanced mixer. Characteristic line 24 shows the conventional frequency converter, and the drain current varies from 40 mA to 15 mA depending on the frequency, whereas characteristic line 25 shows the frequency converter of the present invention, and the drain current does not fluctuate from 25 mA to 20 mA. .

Effects of the Invention As is clear from the above explanation, the present invention connects two passive elements to both ends of the balanced gate electrode of a double-balanced mixer, and applies a gate bias voltage to the connection point between the passive elements. By setting the local oscillation voltage to a constant voltage using a passive element, the current consumption can be made constant with respect to the oscillation frequency, and a wide band can be achieved. Furthermore, since the voltage of the local oscillation signal can be kept constant, the voltage value can be set to the optimum value for noise performance, and distortion performance, noise performance, and conversion loss can be made constant over a wide band.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a frequency converter according to a first embodiment of the present invention, FIG. 2 is a circuit diagram of a frequency converter according to a second embodiment of the present invention, and FIG. 3 is a circuit diagram of a conventional frequency converter. Circuit diagram, 4th
The figure is a frequency vs. current consumption characteristic diagram of a conventional frequency converter according to the present invention. 2.12...Unbalanced/balanced converter, 14...
...Balanced/unbalanced converter. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 4 (MHz)

Claims (3)

[Claims] (1) From one electrode to the other of a pair of gate electrodes of a double-balanced mixer consisting of first, second, third, and fourth field effect transistors, two impedances smaller than the impedance of the gate electrodes are connected. A frequency conversion device characterized in that passive elements are connected in series, and a terminal for supplying a gate control voltage to be applied to the gate electrode of the double-balanced mixer is connected to a connection point between the two passive elements. . (2) The frequency conversion device according to claim (1), wherein the passive element is a resistor. (3) The frequency conversion device according to claim (1), wherein the passive element is a parallel connection of a resistor and a diode.