KR20130036697A - Signal input device digital-rf converter - Google Patents

Abstract

PURPOSE: A device for inputting the signal of a digital-RF converter is provided to improve a signal-noise ratio by generating noise generated by the excessive response of an input signal in a specific frequency or a random frequency. CONSTITUTION: A device for inputting the signal of a digital-RF converter(100) includes a phase-modulated signal input unit inputting a phase-modulated transmission signal into the LO switch(130) of the digital-RF converter; and a digital signal input unit modifying a digital signal in order to correspond to the phase-modulated transmission signal and inputting the modified digital signal into the data switch(121,122) of the digital-RF converter.

Description

SIGNAL INPUT DEVICE DIGITAL-RF CONVERTER}

The present invention relates to a signal input device of a digital-RF converter, and more particularly, to a signal input device of a digital-RF converter for preventing distortion of an output signal generated by a transient response of a digital input signal.

1 is a block diagram showing a transmitter using a conventional digital-RF converter, FIG. 2 is a schematic circuit diagram of an M-bit digital-RF converter, and FIG. 3 is a circuit diagram of a 1-bit digital-RF converter. It is a figure which shows a distortion signal generate | occur | producing in an output signal by the pattern of a signal.

In a transmission stage using a conventional digital-RF converter, the baseband I and Q digital signals have an increased sampling frequency through an interpolator 10 and harmonic components are removed through a digital filter. The local oscillator 50 generates a local oscillation signal, and the quadrature oscillation signal generator 60 generates an I oscillation signal LO_I and a Q oscillation signal LO_Q from the local oscillation signal, thereby converting the digital-RF converters 30 and 40. To pass).

The digital-RF converters 30 and 40 modulate the digital signal into an RF signal according to the I oscillation signal LO_I and the Q oscillation signal LO_Q.

Summer 70 adds the RF signals modulated by digital-to-RF converters 30 and 40, respectively.

The RF signal summed by the summer 70 is amplified by a power amplifier (PA) 80 and band-passed through a band pass filter (BPF) 90 to the antenna 95. Is sent.

In the transmission stage using such digital-RF converters 30 and 40, the digital-RF converters 30 and 40 typically employ an M-bit digital-RF converter, as shown in FIG.

The digital-to-RF converters 30 and 40 ideally input a digital input signal as an ideal square wave and do not generate a distortion signal due to an ideal switching operation.

In practice, however, as shown by the dotted line in FIG. 3, the input signal exhibits a transient response in the transient period where the signal state changes (0-> 1 or 1-> 0). Due to this transient response, the output signal also shows a transient response in the transient response section of the input signal. As a result, since the output signal depends on the pattern of the input signal, there is a problem that the transient response also appears in the output signal due to the transient response of the input signal.

The distortion of the output signal due to the transient response of the input signal acts as noise in the signal band, thereby degrading the signal-to-noise ratio characteristics.

Background art related to the present invention is 'Method and device for digital-to-RF conversion' of US registration number 06937848 (August 30, 2005).

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a signal input device for a digital-to-RF converter which improves the signal-to-noise ratio by causing noise generated by a transient response of an input signal to be generated at a specific frequency or randomly. There is a purpose.

In accordance with an aspect of the present invention, a signal input device for a digital-RF converter includes: a phase modulated signal input unit configured to input a phase-modulated transmission signal to an LO switch of a digital-RF converter; And a digital signal input unit for correcting the digital signal to correspond to the phase-modulated transmission signal and inputting the modified digital signal to a data switch of the digital-RF converter.

The phase modulated signal input unit of the present invention generates a phase modulated transmission signal by phase modulating a transmission signal through the random pulse input from a pulse stream generator that receives a digital clock and generates a random pulse. Characterized in that it comprises a.

The phase modulated signal input unit of the present invention receives a digital clock and generates a phase modulated transmission signal by phase modulating a transmission signal through the square wave of a predetermined period input from a pulse stream generator generating a square wave of a predetermined period. And a phase modulator.

The digital signal input unit of the present invention is characterized in that it comprises a logic circuit for XNOR (Exclusive NOR) the random pulse and raw data input from the pulse stream generator for receiving a digital system clock to generate a random pulse.

The digital signal input unit of the present invention comprises a logic circuit unit for XNOR (Exclusive NOR) the square wave and the raw data of the predetermined period inputted from the pulse stream generator for receiving a digital system clock to generate a square wave of a predetermined period. do.

The signal input device of the digital-RF converter, characterized in that the phase-modulated transmission signal of the present invention is commonly shared to a plurality of digital-RF converter.

The present invention improves signal-to-noise ratio performance by reducing the frequency component of the distortion signal depending on the input signal at a specific frequency, for example clock frequency, rather than in the signal band, and reduces leakage of the transmission signal.

1 is a block diagram showing a transmitter using a conventional digital-RF converter.
2 is a simplified circuit diagram of an M-bit digital-RF converter.
FIG. 3 is a circuit diagram of a 1-bit digital-to-RF converter, in which distortion signals are generated in an output signal by a pattern of a digital input signal.
4 is a block diagram of a signal input device of a digital-RF converter according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating the periodical distortion signal of an output generated by a pattern of a digital input signal input to a digital-RF converter according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating a combination of M unit-weighted digital-RF converters in a transmitter according to an embodiment of the present invention.

Hereinafter, a signal input device of a digital-RF converter according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

4 is a block diagram of a signal input device of a digital-RF converter according to an embodiment of the present invention, and FIG. 5 is generated by a pattern of an input signal input to a digital-RF converter according to an embodiment of the present invention. FIG. 6 is a diagram illustrating a periodicity of a distorted signal of an output, and FIG. 6 is a diagram illustrating a combination of M unit-weighted digital-RF converters in a transmitter according to an embodiment of the present invention.

The signal input device of the digital-RF converter according to an embodiment of the present invention includes a phase modulated signal input part and a digital signal input part, wherein the phase modulated signal input part receives a random pulse or a square wave of a predetermined period from the pulse stream generator 200. Input the phase-modulated transmission signal to the LO switch of the digital-RF converter, the digital signal input unit modifies the digital signal to correspond to the phase-modulated transmission signal, and converts the modified digital signal to the data switch of the digital-RF converter. Enter it.

The phase modulated signal input unit includes an LO phase modulator 300, and the digital signal input unit includes a logic circuit unit 400.

First, the pulse stream generator 200 is shared with the phase modulation signal input unit and the digital signal input unit to input a random pulse or a square wave of a predetermined period to the pulse stream generator 200 and the logic circuit unit 400, respectively. However, the pulse stream generator 200 is not necessarily limited to being shared, and the technical scope of the present invention will include those provided in the pulse stream generator 200 and the logic circuit unit 400 separately.

And a pulse stream generator 200, an LO phase modulator 300, and a logic circuitry 400.

The pulse stream generator 200 receives a digital clock of a digital system (not shown) to generate a random pulse or generate a square wave of a predetermined period to be input to the LO phase modulator 300 and the logic circuit 400. do.

The LO phase modulator 300 receives a transmission signal (LO Wave) of the local oscillator (not shown) and an output of the pulse stream generator 200 to switch the transmission signal and the output of the pulse stream generator 200 to phase the transmission signal. And modulate a phase modulated transmission signal to a LO switch 130 of the digital-RF converter 100.

Here, since the transmission signal of the local oscillator is phase-modulated by the LO phase modulator 300, the digital input signal Raw data should also be changed to correspond to the phase modulation of the transmission signal.

The logic circuit 400 modifies the digital input signal by performing an exclusive NOR (XNOR) of the output of the pulse stream generator 200 and the digital input signal, and modifies the modified digital input signal (Modified data) of the digital-RF converter 100. Inputs are made to the data switches 121 and 122.

When the digital-RF converter 100 receives the phase-modulated transmission signal from the LO phase modulator 300 and the modified digital input signal is input from the logic circuit unit 400, the LO switch 130 and the data switch ( The modulation signal is generated according to the switching operation of 121 and 122. At this time, the LO switch 130 is operated by the phase-modulated transmission signal, and the data switches 121 and 122 are operated according to the modified digital input signal, thereby generating noise generated by the transient response of the input signal at a specific frequency or It is randomly generated to improve the signal-to-noise ratio.

Here, the digital-RF converter 100 includes a current source 140 and a LO switch 130, a pair of data switches 121 and 122, and a pair of inductor loads 111 and 112, as shown in FIG. 4.

The data switches 121 and 122 operate as differential switches in accordance with the digital input signal modified by the logic circuit unit 400 for the positive output terminal and the negative output terminal that are differentially connected to the RF load (not shown). The positive output terminal and the negative output terminal are connected to the RF load through the inductor rods 111 and 112, one terminal of each of the data switches 121 and 122 is connected to the positive output terminal, and the other terminal is connected to the negative output terminal. do. These data switches 121 and 122 operate according to the modified digital input signal input from the logic circuit unit 400.

The remaining terminals of the data switches 121 and 122 are selectively connected to the current source 130 by the operation of the LO switch 130.

Here, the LO switch 130 is operated according to a phase-modulated transmission signal, and at this time, any one of the pair of data switches 121 and 122 is connected to the current source 140.

As such, according to the transmission signal phase-modulated by the LO phase modulator 300, the LO switch 130 operates so that the current source 130 is connected to any one of the pair of data switches 121 and 122, wherein the data switch By switching the 121 and 122 so that the RF load and the current source 140 are connected, the digital input signal is up-converted into an analog RF signal.

The operation of the signal input device of the digital-RF converter according to an embodiment of the present invention will be described in detail.

The pulse stream generator 200 receives a digital clock of a digital system and generates a random pulse or generates a square wave of a predetermined period and inputs it to the LO phase modulator 300 and the logic circuit unit 400.

In this case, the LO phase modulator 300 is operated by receiving a random pulse or a square wave of a predetermined period from the pulse stream generator 200 to phase modulate the transmission signal of the local oscillator to digital-RF into a pulse stream in which 0 and 1 are repeated. Input to LO switch 130 of transducer 100.

When the logic circuit 400 receives a random pulse or a square wave of a predetermined period from the pulse stream generator 200, the logic circuit 400 performs an XNOR with the digital input signal and inputs the data switches 121 and 122 of the digital-RF converter 100. Accordingly, the data switches 121 and 122 of the digital-RF converter 100 operate to form a current path of the digital-RF converter 100.

That is, by switching the LO switch 130 using the phase-modulated transmission signal, the frequency component of the distortion signal depending on the input signal is located at the digital clock frequency instead of the signal band. In addition, when the pulse stream generator 200 generates a random pulse, the frequency components of the distortion signal of the output spectrum are evenly distributed in the frequency band, thereby improving the characteristics of the signal-to-noise ratio and attenuating the output power of the transmission signal. This can reduce transmission signal leakage.

In addition, when the frequency component of the distortion signal generated by the digital input signal is not located in the signal band and is concentrated on a specific frequency such as the sampling frequency of the data, the frequency component is far from the signal band. Can be easily removed.

Meanwhile, in the above-described embodiment, the 1-bit digital-RF converter has been described as an example, but the actual digital-RF converter is composed of a plurality of bits to reduce quantization noise. This is illustrated in FIG. 6.

Referring to FIG. 6, the phase modulated transmission signal is shared in common with each digital-RF converter 100, and is commonly input to the LO switch 130 of each digital-RF converter 100, and the modified digital input signal. Is input to the data switches 121 and 122 of each digital-RF converter 100 through each logic circuit 400.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, I will understand. Accordingly, the true scope of the present invention should be determined by the following claims.

100: digital to RF converter 111,112: inductor load
121,122: data switch 130: LO switch
140: current source 200: pulse stream generator
300: LO phase modulator 400: logic circuit section

Claims (6)

A phase modulated signal input unit configured to input a phase modulated transmission signal to an LO switch of the digital to RF converter; And
And a digital signal input unit for correcting the digital signal to correspond to the phase-modulated transmission signal and inputting the modified digital signal to a data switch of the digital-RF converter. The method of claim 1, wherein the phase modulated signal input unit
And a LO phase modulator for generating the phase modulated transmission signal by phase modulating a transmission signal through the random pulse input from a pulse stream generator for receiving a digital clock to generate a random pulse. Signal input device of RF converter. The method of claim 1, wherein the phase modulated signal input unit
And a LO phase modulator for generating the phase-modulated transmission signal by phase-modulating the transmission signal through the square wave of the predetermined period inputted from a pulse stream generator that receives a digital clock and generates a square wave of a predetermined period. Signal input device of digital to RF converter. The method of claim 1, wherein the digital signal input unit
And a logic circuit for XNORing the random pulses and raw data input from a pulse stream generator that receives a digital system clock to generate random pulses. The method of claim 1, wherein the digital signal input unit
Signal input of the digital-RF converter, comprising a logic circuit for XNOR the square wave of the predetermined period and the raw data input from the pulse stream generator for receiving a digital system clock to generate a square wave of a predetermined period Device. The signal input device of claim 1, wherein the phase-modulated transmission signal is shared in common among a plurality of digital-RF converters.

Images