Description
SIGNAL GENERATOR FOR MULTI-BAND UWB
Technical Field
[1] The present invention relates to a signal generator applied to a multi-band ultra- wideband (UWB) direct-conversion radio-frequency (RF) transmission/reception apparatus, and more particularly, to a signal generator for a multi-band UWB, which does not uses a switch by selection of a division ratio of a prescaler according to an external selection signal, minimizes generation of spurious signals and harmonic signals by generation of only one channel signal at the time of "t=tl", reduces power consumption and a design area by minimization of the number of required components, and thus can be manufactured at a low cost.
[2]
Background Art
[3] Fig. 1 is a functional block diagram of a conventional multi-band UWB signal generator.
[4] Referring to Fig. 1, the conventional multi-band UWB signal generator includes two voltage controlled oscillators 11 and 12, two switches 13 and 14, six /2 dividers 15-20, a /3 divider 21, and a mixer 22. According to a switch isolation degree, a lot of spurious signals are generated and various signals are simultaneously generated. Accordingly, there exists a small difference between a main signal and a noise signal.
[5] In the conventional multi-band UWB generator, many channels periodically hop during a very short time. Accordingly, when many channels coexist, a lot of noise signals are generated due to an inter-channel effect and a hopping time of several nsec cannot be satisfied due to a PLL locking time of several tens μsec.
[6]
Disclosure of Invention Technical Problem
[7] Accordingly, the present invention is directed to a signal generator for a multi-band
UWB, which substantially obviates one or more problems due to limitations and disadvantages of the related art.
[8] It is an object of the present invention to provide a signal generator for a multi-band
UWB, which satisfies a hopping time, generates only one channel signal at the time of "t=tl" by selection of a division ratio of a prescaler according to an external selection signal, reduces power consumption and a design area by minimization of the number of required components (e.g. switches), and thus can be manufactured at a low cost.
[9]
Technical Solution
[10] To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a signal generator applied to a UWB direct-conversion RF transmission/reception apparatus, the signal generator includes: a voltage controlled generator for generating a signal of a 6 GHz band; a PLL (phase locked loop) for locking the 6 GHz band signal to an accurate signal of 6336 MHz; a /4 divider for dividing the 6336 MHz signal from the PLL at a division ratio of /4; an SSBl mixer for mixing the output signal from the /4 divider with the 6336 MHz signal from the PLL; a /2 divider for dividing the mixed signal from the SSBl mixer at a division ratio of /2; a prescaler for dividing the 6336 MHz signal from the PLL at a division ratio of /3, /4 or /6 according to an external selection signal; and an SSB2 mixer for mixing the output signal from the /2 divider with the divided signal from the prescaler.
[H]
Advantageous Effects
[12] As described above, the multi-band UWB signal generator does not uses a switch by selection of a division ratio of a prescaler according to an external selection signal, minimizes generation of spurious signals and harmonic signals by generation of only one channel signal at the time of "t=tl", reduces power consumption and a design area by minimization of the number of required components, and thus can be manufactured at a low cost. [13]
Brief Description of the Drawings [14] Fig. 1 is a functional block diagram of a conventional multi-band UWB signal generator. [15] Fig. 2 is a functional block diagram of a multi-band UWB signal generator according to an embodiment of the present invention. [16] Fig. 3 is a functional block diagram of an SSBl mixer in the multi-band UWB signal generator illustrated in Fig. 2. [17] Fig. 4 is a functional block diagram of an SSB2 mixer in the multi-band UWB signal generator illustrated in Fig. 2. [18] Fig. 5 is a functional block diagram of a prescaler in the multi-band UWB signal generator illustrated in Fig. 2. [19]
Best Mode for Carrying Out the Invention [20] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
[21] Fig. 2 is a functional block diagram of a multi-band UWB signal generator according to an embodiment of the present invention. [22] Referring to Fig. 2, a signal generated at a voltage controlled oscillator (VCO) 110 is locked to an accurate signal of 6336 MHz at a phase locked loop (PLL) 120. The 6336 MHz signal from the PLL 120 is converted into a signal of a 1.5 GHz band by a / 4 divider 130 configured with two /2 dividers. The 1.5 GHz band signal from the /4 divider 130 is mixed with the 6336 MHz signal from the PLL 120 at a single sideband (SSB)I mixer 150 and is thus converted into a signal of a 4.7 GHz band. The 4.7 GHz band signal from the SSB 1 mixer 150 is converted into a signal of a 2.3 GHz band at a /2 divider 160. The 2.3 GHz band signal from the /2 divider 160 is inputted into an SSB2 mixer 180.
[23] Meanwhile, the 6336 MHz signal from the PLL 120 is divided into a 2112 MHz signal, a 1584 MHz signal and a 1056 MHz signal respectively by a /3 divider, a /4 divider and a /6 divider of a prescaler 170 selected by an external selection signal, and only one of the divided signals is inputted into the SSB2 mixer 180 at the time of "t=tl". At this point, the two signals inputted into the SSB2 mixer 180 are respectively combined into desired signals of 3432 MHz, 3960 MHz and 4488 MHz. Table 1 below shows a center frequency (of each channel) of the signals generated from the multi- band UWB signal generator.
[24] Table 1
[25] [26] Fig. 3 is a functional block diagram of the SSBl mixer 150 in the multi-band UWB signal generator illustrated in Fig. 2.
[27] Referring to Fig. 3, an RF signal inputted into a polyphase filter 151 is converted into I (in-phase)/Q (quatrature-phase) signals. The I/Q signals from the polyphase filter 151 are mixed with I/Q signals from the /4 divider 130 at mixers 152 and 153. The mixed signals from the mixers 152 and 153 are amplified at an amplifier 154, and the amplified signals are inputted into the /2 divider 160.
[28] Fig. 4 is a functional block diagram of the SSB2 mixer 180 in the multi-band UWB signal generator illustrated in Fig. 2. [29] Referring to Fig. 4, an RF signal inputted into a polyphase filter 181 is converted into I/Q signals. The I/Q signals from the polyphase filter 181 are mixed with I/Q
signals from the /2 divider 160 at mixers 182, 183, 184 and 185, and the mixed signals are amplified at amplifiers 186 and 187.
[30] Fig. 5 is a functional block diagram of the prescaler 170 in the multi-band UWB signal generator illustrated in Fig. 2. One of the /3, /4 and /6 dividers in the prescaler 170 are selected by the external selection signal.
[31] An operation of each of the above dividers will now be described with reference to
Fig. 5.
[32] For /3 division operation, the /3 divider is selected from a /2 or /3 divider block 171 by an external selection signal MCl. The output signal from the selected /3 divider is selected by an selection signal MC2 at a 2:1 multiplexer (MUX) 173, and the selected signal is inputted into the SSB2 mixer 180. For /4 division operation, the /2 divider is selected from the /2 or /3 divider block 171 by the external selection signal MCl. The output signal from the selected /2 divider is inputted into a /2 divider 172. The output signal from the /2 divider 172 is selected by the external selection signal MC2 at the 2:1 MUX 173, and the selected signal is inputted into the SSB2 mixer 180. For /6 division operation, the /3 divider is selected from the /2 or /3 divider block 171 by the external selection signal MCl. The output signal from the selected /3 divider is inputted into the /2 divider 172. The output signal from the /2 divider 172 is selected by the external selection signal MC2 at the 2:1 MUX 173, and the selected signal is inputted into the SSB2 mixer 180. Consequently, only one of many channels exists at the time of "t=tl", thereby suppressing a spurious signal and a harmonic signal.
[33] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.