JPH0758552A - Frequency converter hybrid ic - Google Patents

Abstract

PURPOSE:To provide a small sized frequency converter hybrid IC at a low loss. CONSTITUTION:The frequency converter hybrid IC has a function of eliminating an image frequency of a local oscillation signal and an RF 90 deg. directional coupler 11 being an important component of the frequency converter is formed by a strip line of tri-plate structure to attain the small sized frequency converter at a low loss. Furthermore, the effect on terminals of the IC being a problem at a high frequency is corrected by a lumped constant circuit to attain hybrid circuit integration to attain ease of manufacture and to improve the reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to high frequency (several hundred MHz to
VICS (Vehicle Information Communication S) is a receiver that receives and down-converts radio waves of several GHz.
ystem) receiver, GLONASS (Global Orbiting Navig)
ation Satellite System) receiver, GPS (Global Posi
tioning System) In the receiver etc., the RF frequency
The present invention relates to a frequency converter for converting to an F frequency.

[0002]

2. Description of the Related Art FIG. 5 shows the configuration of a conventional frequency converter. This frequency converter has band pass filters 1 and 2 and frequency converters 3 and 4. Local oscillator 5 or 6
The image frequency of the local oscillation frequency of is, in the case of lower local (the local oscillation frequency is lower than the input signal frequency), expressed as (image frequency) = (local oscillation frequency)-(IF frequency), and the upper local (local oscillation frequency Is higher than the input signal frequency), (image frequency) = (local oscillation frequency) + (IF frequency).

[0003]

In the frequency conversion section of FIG. 5, the necessary R is necessary in order to prevent the image frequency of the local oscillation frequency of the local oscillator 5 or 6 from being mixed in the IF signal.
The band pass filters 1 and 2 for selecting only the F signal are inserted in front of the frequency converters 3 and 4 to remove unnecessary image frequencies. Since the image frequency in the RF band is a frequency that is twice the IF signal frequency away from the RF signal frequency, in the case of the conventional method in which the frequency conversion is performed by this method, the higher the RF signal frequency, the more the IF signal frequency The lower the value, the higher the required performance for the bandpass filter, the higher the Q required, and the more difficult it becomes to secure the performance.

In the conventional method, when a high Q filter capable of removing only the required RF signal in the RF signal band and selecting the image frequency cannot be formed, the frequency of two or more stages as shown in FIG. 5 is used. Converting to obtain the final IF frequency, or removing the image frequency by configuring an image rejection type frequency converter with a large Teflon substrate or alumina substrate, but in the former case, the circuit becomes large and complicated. Therefore, it is difficult to improve reliability and miniaturize. In the latter case, since the RF 90-degree directional coupler is large, it is difficult to miniaturize, and when configuring a hybrid IC at a high frequency, it is difficult to reduce the size of the receiver substrate. Impedance matching at the connection is difficult. Further, when the oscillation frequency of the local oscillator becomes high, there is a drawback that the current consumption of the synthesizer of the local oscillator increases.

The object of the present invention is to eliminate the abovementioned drawbacks.

[0006]

According to the present invention, a local oscillator signal used in a frequency converter of a receiver and used in a frequency converter for converting a received RF signal into an IF signal is
It is a second harmonic wave frequency converter using a frequency of 1/2 of a basic local oscillation frequency signal, and removes an unnecessary local oscillation frequency image signal which is frequency-converted to the same frequency as the IF signal and converts it to an IF signal. In a frequency converter that achieves the function to perform with an RF 90-degree directional coupler,
The 90-degree directional coupler is composed of a wideband, low-loss strip-coupled line with a triplate structure using a printed circuit board, and the hybrid IC board and the receiver printed circuit board have mutual input / output impedances. The frequency is characterized in that the impedance mismatch generated at the input / output pin of the hybrid IC substrate, which is the connection part, is corrected in advance by a lumped constant capacitor to obtain a characteristic impedance matching this impedance. A converter hybrid IC is obtained.

As described above, in order to eliminate the above-mentioned drawbacks, the present invention is an image rejection type having a function of removing the image signal of the oscillation frequency of the local oscillator that is mixed in the IF signal when the frequency is converted. By using the frequency converter of, the specification of the band pass filter inserted in the RF band is relaxed. In addition, by reducing the current consumption of the synthesizer by using a frequency converter of the second harmonic wave that uses the local oscillation frequency of 1/2 of the fundamental wave, the RF 90 degree directional coupler is a strip line with a triplate printed circuit board. By making it a coupled line, it can be made smaller than the branch line and rat race made with microstrip line,
In addition, since the band can be widened, 1 / of the fundamental wave
The feature is that 2 local oscillation frequencies can be used. According to the present invention, the frequency converter having the above-mentioned characteristics is small in size, low in loss, and the circuit is matched by a lumped capacitor in order to eliminate the influence of the terminals of the IC which cause impedance mismatch. It is a hybrid IC characterized by that.

[0008]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 shows a frequency converter hybrid IC according to an embodiment of the present invention. In FIG. 1, 11 is RF
90 degree directional coupler, 12 and 13 are diode input matching circuits, 14 and 15 are frequency conversion diodes, and 16 and 17 are diode output matching circuits. 18 is an IF 90-degree directional coupler, 19 is a terminating resistor,
20 and 21 are hybrid IC matching circuits.

The RF 90-degree directional coupler 11 is a 90-degree directional coupler having a relative band of 2 or more, and has the same two levels (90 degrees in phase difference) between the RF input signal and the local oscillation input signal. -3 dB) signal is output. In order to realize a 90-degree directional coupler having a specific bandwidth of 2 or more, a multilayer printed circuit board is used to construct a triplate structure coupling line. The directional coupler having this structure has an advantage that a large relative band can be secured and an advantage that loss is small.

FIG. 2 shows a layer structure of a printed circuit board for realizing the RF 90-degree directional coupler 11 of the hybrid IC. In FIG. 2, 31 and 34 are ground layer copper foils, 32 and 33 are stripline coupled line copper foils, 3
Reference numeral 5 is a printed circuit board dielectric. When making a directional coupler with stripline coupled line copper foils 32 and 33 sandwiched between ground layer copper foils 31 and 34, the line width and line length have optimum values, but their approximate values are λ of the operating frequency. / 4
It is a degree. If a 90-degree directional coupler is made with such a printed circuit board pattern, the ratio band of the coupling band of 3 dB becomes about 2, and it can be applied to a frequency converter of 2 times. It can be smaller than the branch line and rat race known as vessels.

In FIG. 1, diode input matching circuits 12 and 13 and diode output matching circuit 1 are shown.
Reference numerals 6 and 17 are matching circuits for producing the characteristics of the diodes, which are circuits for matching the impedances of RF, local and IF. Since the frequency conversion diodes 14 and 15 are frequency converters that operate at a local oscillation frequency that is ½ of the fundamental wave, a pair of diodes oriented in the opposite direction are used. The IF 90-degree directional coupler 18 is a circuit formed by a lumped constant that outputs two signals having a phase difference of 90 degrees in the IF signal band at the same level (-3 dB).

Next, the operation of the circuit shown in FIG. 1 will be described. To operate the circuit of FIG. 1, an RF signal (including image) and a local oscillation signal are input. The RF signal, the local oscillation signal, the IF signal, and the image signal when frequency-converted as the lower local have a frequency relationship given by the following formula.

(RF frequency) = (local oscillation frequency) × 2
+ (IF frequency) (Image frequency) = (Local oscillation frequency) x 2- (IF
Frequency) The input RF signal and local oscillation signal, when passing through the RF 90-degree directional coupler 11, output a local oscillation signal with a phase delay of 90 degrees compared with in 'in FIG. A desired signal and an image signal with a phase delay of 1 degree are output. Then, in the diodes 14 and 15, the desired signal, the image signal, and the local oscillation signal are mixed to form an IF signal. When the IF signal of'in FIG. 1 which is internally converted is input to the IF 90-degree directional coupler 18, the phase relationship between the desired signal and the image signal of the IF signal input from 'remains unchanged. The signal is output to the IF signal output terminal while maintaining the state, but the IF input from
The desired signal is delayed by 90 degrees and the image signal is output in a relative phase relationship of advancing by 90 degrees. As a result, at the IF signal output end, the desired signals are in-phase and combined, and the image signals are opposite-phase and combined, and the IF signal output is converted into the IF signal and output.

FIG. 3 is an external view of the present frequency converter hybrid IC. Attaching feet to this frequency converter, a hybrid IC having a shape as shown in FIG. 41 in FIG. 3 is a hybrid I
A substrate C is shown, and a reference numeral 42 is a connection terminal with the receiving unit. In a hybrid IC with such a shape, the higher the input frequency to the frequency converter, the more the length of this mounting leg that connects the IC and the receiver board becomes more significant, and it is designed with an input / output impedance of 50Ω. The frequency converter will cause impedance mismatch.

FIG. 4 shows a hybrid IC matching circuit (impedance matching circuit) 20 (or 2) of FIG.
The details of 1) are shown, 51 is a hybrid IC connection terminal, and 52 and 53 are capacitors. This circuit corrects this mismatch by using a lumped constant circuit instead of connecting with a distributed constant line of 50Ω impedance, and the hybrid IC functions by adding this circuit.

[0017]

As described above, the frequency converter hybrid IC according to the present invention has a function of removing the image frequency of the local oscillation signal, which is one of the roles of the band pass filter inserted in the preceding stage of the frequency converter. Therefore, by making the RF 90-degree directional coupler, which is an important component in this frequency converter, with a strip line having a triplate structure, a small frequency converter with low loss can be obtained. Further, when a hybrid substrate is used, a lumped constant circuit corrects the influence of the terminals of the IC, which is a problem particularly at high frequencies, so that a hybrid IC can be realized, which can be easily manufactured and reliability can be improved. .

[Brief description of drawings]

FIG. 1 is a block diagram of a basic circuit of a frequency converter hybrid IC according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a printed circuit board for realizing the RF 90-degree directional coupler 11 of FIG.

FIG. 3 is an external view of the present frequency converter hybrid IC.

FIG. 4 is a hybrid IC matching circuit 20 of FIG.
The figure which showed the detail of (or 21).

FIG. 5 is a block diagram of a conventional frequency conversion unit.

[Explanation of symbols]

 11 RF 90 Degree Directional Coupler 12 Diode Input Matching Circuit 13 Diode Input Matching Circuit 14 Frequency Conversion Diode 15 Frequency Conversion Diode 16 Diode Output Matching Circuit 17 Diode Output Matching Circuit 18 IF90 Degree Directional Coupler 19 Termination Resistor 20 Hybrid IC Matching circuit 21 Hybrid IC matching circuit

Claims (1)

[Claims] 1. A local oscillation signal used in a frequency converter of a receiver and used in a frequency converter for converting a received RF signal into an IF signal has a half of a basic local oscillation frequency signal.
Is a second-harmonic frequency converter using the frequency of
In the frequency converter, the function of removing an image signal having an unnecessary local oscillation frequency that is frequency-converted to the same frequency as the signal and converting it into an IF signal is achieved by using an RF 90-degree directional coupler. The coupler is composed of a wideband, low-loss strip-coupled line with a triplate structure using a printed circuit board, and a hybrid I
The input and output impedances of the C board and the receiver printed board are predetermined, and the impedance mismatch generated at the input and output pins of the hybrid IC board, which is the connection part, is corrected by a lumped constant capacitor. The frequency converter hybrid IC is characterized in that the characteristic impedance matches the impedance.