JPH02124608A - Frequency conversion circuit - Google Patents

Abstract

PURPOSE:To eliminate carrier leakage caused due to the variance in the characteristic of components of a modulation circuit by employing a double balanced modulation circuit, a phase inverter and an adder so as to apply arithmetic operation. CONSTITUTION:A frequency conversion carrier 2 is used to control 1st and 2nd double balance modulation circuits 3, 4 thereby converting the frequency. That is, when an input signal 1 is inputted, it is subject to frequency conversion at the 1st double balance modulation circuit 3 by using the conversion carrier 2. On the other hand, the input signal passes through a 1st phase inverter 5 simultaneously, then the signal is subject to frequency conversion by the 2nd double balance modulation circuit 4 and after the phase restoration by a phase inverter 6, the output after the phase restoration and the output of the 1st double balance modulation circuit 3 are added by an adder 7 to produce an output signal 8. Thus, carrier leakage is prevented for the frequency conversion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a frequency conversion circuit, and more particularly to a frequency conversion circuit using a double-balanced modulation circuit.

[Conventional technology]

Conventionally, a frequency conversion circuit using such a double-balanced modulation circuit has been realized by modulating an input signal using a frequency conversion carrier.

FIG. 2 is a frequency conversion circuit diagram showing an example of such a conventional system.

As shown in Figure 2, this frequency conversion circuit converts the input signal ↓
and frequency conversion carrier 2 are input, output signal 8
is the result of multiplying input signal 1 and carrier 2.

For example, if the phase of input signal 1 is Sinα and the phase of carrier 2 is Sinβ, then the phase of output signal 6 is SinαS
becomes inβ. Expanding this, 1/2(Cos(α
−β)−Cos(α+β)), therefore, the frequency α of input signal 1 becomes 1αβ1 and α+
It is converted to a frequency that has a phase with β. Note that the input signal 1 is connected to the bias 1o and the transistor Q5. Q6 and resistors R, , R4 constitute a differential stage, frequency conversion carrier 2 constitutes a differential stage with bias 9, transistors Q+ to Q4 and resistors R1R2, and transistor element and resistor R5 are regulated by bias 11. The transistor Q8 and the resistor R6 constitute a current source, and the transistor Q8 and the resistor R6 constitute an output stage.

[Problem to be solved by the invention]

The above-mentioned conventional frequency conversion circuit has an advantage in that the circuit configuration is easy and in terms of cost, but it has the disadvantage that the frequency conversion characteristics are easily changed due to variations in the characteristics of the transistor elements that constitute the circuit.

For example, in FIG. 2, if there are variations in the BE voltages of the transistors Q5 and Q6, the conversion carrier 2 will leak to the output signal 8. In particular, consumer V
When the frequencies of the input signal and the carrier for conversion are very close, as in the case of frequency conversion of a color signal in a TR, this carrier leak is often made into an intermediate pressure.

An object of the present invention is to provide a frequency conversion circuit that can convert frequencies while preventing such carrier leakage.

[Means to solve the problem]

The frequency conversion circuit of the present invention is a frequency conversion circuit using a double-balanced modulation circuit, and includes a first double-balanced modulation circuit and a first phase inverter each connected to an input signal terminal; a second double-balanced modulation circuit connected to the inverter; a second phase inverter connected to the second double-balanced modulation circuit; and a second phase inverter connected to the output signal terminal and connected to the first double-balanced modulation circuit. an adder that adds the output of the modulation circuit and the output of the second phase inverter, and controls the first and second double-balanced modulation circuits using a frequency conversion carrier to increase the frequency. configured to perform the conversion.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a frequency conversion circuit showing one embodiment of the present invention.

As shown in FIG. 1, in this embodiment, a first double-balanced modulation circuit 3 and a phase inverter 5 composed of an inverter are connected to the input signal terminal 1, respectively, and the output side of the phase inverter 5 is connected to the input signal terminal 1. A second double-balanced modulation circuit 4 is connected to. Also,
A second phase inverter 6 similar to the first phase inverter 5 described above is connected to the output side of the double balanced modulation circuit 4, and furthermore, the output of the second phase inverter 6 and the first phase inverter 6 are connected to each other. A normal adder 7 is provided to add the output of the double-balanced modulation circuit 3, and outputs the calculation result to an output signal terminal 8.

Note that a carrier for conversion is inputted from the carrier terminal 2 for frequency conversion, and controls the first and second double balanced modulation circuits 3 and 4.

In such a frequency conversion circuit, when an input signal 1 is input, it is frequency converted by a first double-balanced modulation circuit 3 using a conversion carrier 2. Meanwhile, at the same time, the input signal 1 passes through the first phase inverter 5 and then passes through the second double-balanced modulation circuit 4.
After frequency conversion by the phase inverter 6 and phase restoration by the phase inverter 6,
The output after the phase restoration and the output of the first double-balanced modulation circuit 3 are added together by an adder 7 to obtain an output signal 8.

For example, input signal 1 is Sinψ, conversion carrier 2 is Si
If nγ, the phase of the output of the modulation circuit 3 is SinψSin
γ, and the phase of the output of the modulation circuit 4 is -8 inψSinγ. On the other hand, if the leakage level coefficient for the input signal is K (IKI<1), then the leakage of conversion carrier 2 is
It becomes in7. Therefore, if the modulation circuits 3 and 4 have the same value, the signal phase at the output of the adder 7 is (SinψS in7+KS in7)+(-(-
3inψSi nγ+KS i nγ) )=2Si
nψ5in7, and the leakage amount is canceled out and removed.

〔Effect of the invention〕

As explained above, the frequency conversion circuit of the present invention uses a double-balanced modulation circuit, a phase inverter, and an adder to perform calculations to eliminate carrier leakage caused by variations in characteristics of elements constituting the modulation circuit. It has the effect of being able to be removed.

61

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a frequency conversion circuit showing an embodiment of the present invention, and FIG. 2 is a diagram of a double balanced modulation circuit showing an example of the conventional art. 1... Input signal, 2... Frequency conversion carrier, 3
．． 4... Double balanced modulation circuit, 5, 6... Phase inverter, 7... Adder, 8... Output signal.

Claims (1)

[Claims] In a frequency conversion circuit using a double-balanced modulation circuit,
a first double-balanced modulation circuit and a first phase inverter connected to input signal terminals, a second double-balanced modulation circuit connected to the first phase inverter, and a second double-balanced modulation circuit connected to the first phase inverter; a second phase inverter connected to the double-balanced modulation circuit; and an adder connected to the output signal terminal for adding the output of the first double-balanced modulation circuit and the output of the second phase inverter. 1. A frequency conversion circuit comprising: a carrier for frequency conversion to control the first and second double-balanced modulation circuits to perform frequency conversion.