KR0149305B1 - Carrier leakage eliminating apparatus of frequency converter - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier leakage elimination device of a frequency converter, comprising: a balanced modulator for generating a converted frequency by inputting a signal having a constant frequency generated from a local oscillator and a signal for frequency conversion; and a frequency in the balanced modulator. Analog communication and video signal processing integrated circuits consist of a carrier leakage component removal system that removes carrier and leakage components by detecting the level and returning it to the balanced modulator by using a sampling pulse matching the converted signal and the output waveform from the balanced modulator. It is a system that automatically removes carrier leakage component generated from frequency conversion circuit, which is an essential function in RFC, regardless of mismatch of each element and manufacturing method of integrated circuit. Since no electrical fine tuning is required, it is possible to reduce the manufacturing cost by improving productivity, and also have the effect of securing a competitive advantage over similar products in the characteristics of integrated circuit products. The present invention relates to a carrier leakage elimination device of a converter.

Description

Carrier Leakage Removal Device of Frequency Converter

1 is a block diagram of a carrier leakage elimination device of a frequency converter according to an embodiment of the present invention,

2 is a detailed circuit diagram of a carrier leakage elimination device of a frequency converter according to an embodiment of the present invention,

3 is an output waveform diagram of a balance modulator according to an embodiment of the present invention,

4 is a waveform diagram of sampling pulses output from a sampling signal generator according to an exemplary embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

100: balance modulator 200: carrier leakage component removal system

210: amplifier 220: carrier leakage elimination circuit

230: capacitor 221: sampling signal generation unit

222: comparison unit

The present invention relates to a carrier leakage elimination device of a frequency converter. More specifically, in a balanced modulator, a frequency that greatly reduces carrier leakage components without a control terminal external to a chip is used. A carrier leakage elimination device of a converter.

In general, balanced modulators, which are used in analog communication circuits and frequency conversion circuits, have a constant frequency generated from a local oscillator and a signal for frequency conversion. Modulated Input is used to generate the converted frequency. At this time, the balanced modulator suppresses (minimizes) leakage of the carrier signal at the output of the frequency conversion circuit.

However, in most of the balanced modulators that are actually used, offsets caused by mismatches of mismatches and mismatches between devices in an integrated circuit (IC) or individual discrete components constituting the balanced modulator are offset. The voltage suppression ability of the carrier is significantly reduced.

Therefore, in order to remove the carrier component, a balanced terminal is installed in the balance modulator to adjust the input offset to adjust the carrier component, and a band stop filter is implemented at the output of the balance modulator. There is a way to remove it.

However, in the conventional technique described above, a method of adjusting a carrier component by adjusting an input offset by installing an adjustment terminal outside the chip in a balance modulator is not practical for commercialization because there is an adjustment terminal, and also eliminates bands at the output of the balance modulator. The implementation of the band stop filter to remove the carrier component requires very precise characteristics of the stop portion of the band cancellation filter. Therefore, the implementation of such a filter is very complicated, and thus, even if the circuit is implemented, the cost is low. It is very expensive, and also the implementation of such a filter in the chip is also a problem that the circuit becomes very large, resulting in an increase in chip size, resulting in an increase in the cost of integrated circuit manufacturing.

Accordingly, an object of the present invention is to provide a carrier leakage elimination device for a frequency converter that greatly reduces the carrier leakage component without the need for an external adjustment terminal in a balanced modulator.

As a means for achieving the above object, the configuration of the present invention comprises a balanced modulator for generating a converted frequency by inputting a signal having a constant frequency generated in a local oscillator and a signal desired for frequency conversion, and in the balanced modulator It consists of a carrier leakage component removal system that removes carrier leakage components by detecting a level and returning it to the balanced modulator using a sampling pulse matching the frequency-converted signal and the output waveform from the balance modulator.

The carrier leakage component removal system includes a balanced modulator output signal using an amplifier configured to determine an amount of carrier leakage removed, and a signal in which a carrier input signal and an output signal frequency-converted by the balanced modulator are output through the amplifier. The carrier leakage elimination circuit which removes the carrier leakage component in the circuit, and the capacitor which detects the output signal level of the said amplification part.

The configuration of the carrier leakage elimination circuit may include a sampling signal generation unit for generating a sampling signal according to a carrier input signal in a sampling and hold scheme, and a detection voltage detected by the capacitor in a sampling pulse period output from the sampling signal generation unit. It consists of a comparator which feeds back to the balance modulator.

With the above configuration, the most preferred embodiment which can be easily carried out by those skilled in the art with reference to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a carrier leakage elimination device of a frequency converter according to an embodiment of the present invention, and FIG. 2 is a detailed circuit diagram of a carrier leakage eliminating device of a frequency converter according to an embodiment of the present invention.

A balanced modulator 100 for generating a converted frequency by inputting a signal having a constant frequency generated from a local oscillator and a signal for frequency conversion, and a frequency-converted signal and balanced modulator 100 in the balance modulator 100. The carrier leakage elimination system 200 removes a carrier leakage component by detecting a level by using a sampling pulse matching the output waveform of the circuit) and returning it to the balanced modulator 100.

The carrier leakage elimination system 200 includes an amplifier 210 that determines an amount of carrier leakage component removal, and a carrier input signal and an output signal frequency-converted by the balance modulator 100. The carrier leakage elimination circuit 220 removes the carrier leakage component from the balanced modulator 100 output signal using the signal outputted through the signal, and the capacitor 230 detects the output signal level of the amplifier.

The configuration of the carrier leakage elimination circuit 220 includes a sampling signal generator 221 for generating a sampling signal in accordance with a carrier input signal in a sampling and hold scheme, and a sampling pulse period output from the sampling signal generator 221. Comparing unit 222 for returning the detected voltage detected by the capacitor 230 to the balance modulator 100.

The operation of the carrier leakage elimination device of the frequency converter according to the embodiment of the present invention by the above configuration is as follows.

The carrier signal applied from the outside is input to the sampling signal generator 221 and the balance modulator 100.

The balance modulator 100 modulates the modulated signal by inputting a modulated signal to be modulated in addition to the carrier signal.

In this case, the output signal should output only a signal modulated while the carrier signal component is suppressed.

However, in practice, the signal output from the balance modulator 100 follows the waveform of the carrier signal as shown in FIG. That is, it contains a carrier signal.

Therefore, the leakage component of the carrier signal included in the signal output from the balance modulator 100 should be removed.

Accordingly, the present invention performs the following operation to remove the carrier leakage component.

First, a modulated signal having the carrier leakage component is input to the amplifier 210. Here, the amplifier 210 amplifies a carrier including a carrier leakage component according to the gain. In this case, the carrier leakage component to be removed is determined according to the gain amount of the amplifier 210, that is, the amount of amplification. Accordingly, the designer may determine the removed carrier leakage component by adjusting the gain of the amplifier 210.

For example, when the carrier leakage component at the balanced modulator 100 output is -40 dB or less, assuming that the output deviation of the carrier leakage elimination circuit 220 itself is 5 mV (how to design the carrier leakage elimination circuit 220 The output deviation may be different depending on the output). The level LEVEL output from the amplifier 210 should be at least 500 mVpp.

20 * LOG (5/500) = -40 dB

After the carrier leakage component has been detected in the carrier leakage elimination circuit 220, to ensure that the detected voltage returning to the balanced modulator 100 can be less than -40 dB of carrier leakage component that can be output from the balanced modulator 100. Will be.

The signal amplified by the amplifier 210 is input to the comparator 222 of the carrier leakage circuit 220.

The comparator 222 inputs sampling signals SP1, / SP1, SP2, / SP2 output from the sampling signal generator 221 shown in FIG. 4 in addition to the signals output from the balance modulator 100. do.

The sampling signal generator 221 receives a carrier signal and generates the sampling signals SP1, / SP1, SP2, and / SP2, and the generated signals SP1, / SP1, SP2, and / SP2 are input. Depending on the frequency of the carrier signal and the waveform output from the balance modulator 100, the width (width) and period may be changed by the user in the design. By varying the sampling signal in this way, it is possible to apply to frequency conversion of all signals.

Here, the sampling signal generator 221 outputs a sampling signal consisting of sampling signals SP1 and / SP1 and sampling signals SP2 and / SP2 for one period of the carrier signal.

The sampling signals SP1 and / SP1 and the sampling signals SP2 and / SP2 are sampled at different time points.

Here, each of the sampling signals is divided into positive signals SP1 and SP2 and negative signals / SP1 and / SP2, which are input to the comparator 222 to transmit transmission gates (not shown) in the comparator 222. to drive a transmission gate.

Accordingly, the comparison unit 222 compares the amplified signal input through the amplifier 210 with respect to the section in which the sampling signals SP1, / SP1, SP2, and / SP2 are input.

That is, the comparison unit 222 detects the amplified signal input from the amplifying unit 210 in the interval between the sampling signals SP1 and / SP2 and the sampling signals SP2 and / SP2. Then, the detected level signal, that is, the detected voltage for each sampling period is compared.

In the comparison, if the levels for each sampling interval are the same, it means that there is no carrier leakage component to be removed, and if the levels being compared are different, it means that there is a leakage component of the carrier to be removed. .

Accordingly, the comparison unit 222 applies a signal corresponding to the difference of the compared signal to the external capacitor.

The external capacitor causes the applied signal to be a DC component and returns to the balance modulator 100.

Then, the balance modulator 100 receives a signal of a DC component input from the external capacitor to change the level of the output voltage. That is, the signal output from the balance modulator 100 outputs a signal whose level is shifted by a comparison value compared by the comparator 222 to a signal before a feedback signal exists.

In other words, the DC signal applied from the external capacitor removes the voltage offset of the balanced modulator 100 input signal, thereby eliminating the carrier leakage component at the balanced modulator output.

The signal output from the balance modulator 100 is again input to the amplifier 210, amplified and compared to the comparator 222, where the values compared by the comparator 222 are equal.

As described above, in the embodiment of the present invention, the carrier leakage component generated in the frequency conversion circuit, which is an essential function of the analog communication and video signal processing integrated circuit, is automatically generated regardless of the mismatch of each element and the manufacturing method of the integrated circuit. This system eliminates the need for any electrical fine-tuning in order to eliminate carrier leakage in the manufacturing of electronic products, which can reduce the manufacturing cost and increase the productivity. It is possible to provide a carrier leakage eliminator of a frequency converter having an effect of securing a relatively competitive advantage over similar products.

This effect of the present invention can be used in the field of analog communication and frequency conversion.

Claims (3)

A balanced modulator that generates a modulated frequency by inputting a signal having a constant frequency generated by a local oscillation unit and a signal to be frequency-converted, and a frequency-converted signal at the balance modulator, and matching the output waveform at the balance modulator. A carrier leakage elimination device for a frequency converter, comprising a carrier leakage component removal system for level detection using a sampling pulse and returning the detected signal to the balanced modulator to remove carrier leakage components. The system of claim 1, wherein the carrier leakage component removal system comprises an amplifier configured to determine a carrier leakage component removal amount, a signal in which a carrier input signal and an output signal frequency-converted by the balance modulator are output through the amplifier. A carrier leakage elimination device for a frequency converter, comprising a carrier leakage elimination circuit for removing carrier leakage components from a balanced modulator output signal and a capacitor for detecting an output signal level of the amplifying section. The method of claim 2, wherein the carrier leakage elimination circuit comprises a sampling signal generator for generating a sampling signal in accordance with a carrier input signal in a sampling-hold method, and by the capacitor in a sampling pulse period output from the sampling signal generator. And a comparator for returning the detected detected voltage to the balanced modulator.