WO2008029999A1

WO2008029999A1 - Signal processing apparatus

Info

Publication number: WO2008029999A1
Application number: PCT/KR2007/003965
Authority: WO
Inventors: Alexander Belonozhkin; Sergey Khverev; Sergey Sergeyev; Kyung Soo Park; Seung Wook Lee; Jung Oh Lee; Woo Kil Jung
Original assignee: Lg Innotek Co., Ltd
Priority date: 2006-09-05
Filing date: 2007-08-20
Publication date: 2008-03-13

Abstract

Provided is a signal processing apparatus. The signal processing apparatus comprises an image rejection mixer, an oscillator, a switching unit, and a transmission signal processing unit and a reception signal processing unit. The image rejection mixer up-converts transmission signals and down-converts reception signals. The oscillator provides oscillation frequency signals to the image rejection mixer, and the switching unit is connected to the image rejection mixer to switch a transmission path and a reception path to selectively pass transmission signals and reception signals. The transmission signal processing unit and the reception signal processing unit are connected to the switching unit to process transmission signals and reception signals, respectively.

Description

SIGNAL PROCESSING APPARATUS

Technical Field

[1] Embodiments relate to a signal processing apparatus.

Background Art [2] A signal processing apparatus for transmitting and receiving data using radio frequency (RF) signals is used for not only a mobile communication terminal but also a near field communication (NFC) system such as an ultra wide band and Bluetooth.

Disclosure of Invention

Technical Problem

[3] Embodiments provide a signal processing apparatus.

[4] Embodiments also provide a signal processing apparatus for simplifying a transmission/reception path of data to reduce use of a device.

[5] Embodiments also provide a signal processing apparatus for reducing use of an active device in an RF signal processing region to reduce power consumption, and extend a dynamic range of a signal processing.

[6] Embodiments also provide a signal processing apparatus for reducing use of a low noise amplifier and a power amplifier in an RF signal processing region.

[7] Embodiments also provide a signal processing apparatus for reducing use of a device operating in an RF signal processing region to make circuit design and an operation easy. Technical Solution

[8] In one embodiment, a signal processing apparatus comprises: an image rejection mixer up-converting transmission signals and down-converting reception signals; an oscillator for providing oscillation frequency signals to the image rejection mixer; a switching unit connected to the image rejection mixer to switch a transmission path and a reception path to selectively pass transmission signals and reception signals; and a transmission signal processing unit and a reception signal processing unit connected to the switching unit to process transmission signals and reception signals, respectively.

[9] In another embodiment, a signal processing apparatus comprises: an image rejection mixer up-converting transmission signals and down-converting reception signals; an oscillator for providing oscillation frequency signals to the image rejection mixer; a baseband signal processing unit connected to the image rejection mixer to amplify and/ or attenuate transmission signals and reception signals in a baseband; a switching unit connected to the baseband signal processing unit to switch a transmission path and a reception path to selectively pass transmission signals and reception signals; and a transmission signal processing unit and a reception signal processing unit connected to the switching unit to process transmission signals and reception signals, respectively. [10] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

Advantageous Effects

[11] Embodiments can provide a signal processing apparatus that can simplify a transmission/reception path of data to reduce use of a device.

[12] Embodiments can also provide a signal processing apparatus for simplifying a transmission/reception path of data to reduce use of a device.

[13] Embodiments can also provide a signal processing apparatus for reducing use of an active device in an RF signal processing region to reduce power consumption, and extend a dynamic range of a signal processing.

[14] Embodiments can also provide a signal processing apparatus for reducing use of a low noise amplifier and a power amplifier in an RF signal processing region.

[15] Embodiments can also provide a signal processing apparatus for reducing use of a device operating in an RF signal processing region to make circuit design and an operation easy. Brief Description of the Drawings

[16] Fig. 1 is a view explaining a signal processing apparatus according to an embodiment.

[17] Fig. 2 is a view exemplarily illustrating a passive image rejection mixer of a signal processing apparatus according to an embodiment. Mode for the Invention

[18] A signal processing apparatus will be described in detail according to an embodiment with reference to the accompanying drawings.

[19] Fig. 1 is a view explaining a signal processing apparatus according to an embodiment, and Fig. 2 is a view exemplarily illustrating a passive image rejection mixer of a signal processing apparatus according to an embodiment. The signal processing apparatus can be applied to a superheterodyne method and direct conversion. In the superheterodyne method, after RF signals are converted into intermediate frequency (IF) signals, a sufficient amplifying degree and selection degree are achieved, and the signals are converted into baseband signals. In the direct conversion, which is also called a zero IF method, RF signals are directly converted into baseband signals. Though a direct conversion type signal processing apparatus is proposed in an embodiment, a superheterodyne signal processing apparatus can be provided by adding devices for converting RF signals into IF signals and processing the IF signals.

[20] Also, a receiving apparatus according to an embodiment can be applied to a variety of radio communication systems such as a NFC system including an ultra- wide band (UWB) system, a Bluetooth system using frequencies in a band of about 2.4 GHz, a near field radio communication system using millimeter frequencies in a band of about 60 GHz, and Zigbee technology for construction of a home network. In an embodiment, the receiving apparatus is applied to the UWB system.

[21] The signal processing apparatus of Fig. 1 includes: a band pass filter (BPF) 10, a passive IRM 20, a voltage control oscillator (VCO) 30, first and second low pass filters (LPFs) 41 and 42, first and second attenuators 51 and 52, a switching unit 60, first and second amplifiers 71 and 72, third and fourth low pass filters (LPFs) 81 and 82, and first and second driving amplifiers 91 and 92.

[22] In an embodiment, the BPF 10, the passive IRM 20, the first and second LPFs 41 and

42, the first and second attenuators 51 and 52 are bi-directional (transmit signal in both directions), and the BPF 10, the passive IRM 20, the first and second LPFs 41 and 42, and the first and second attenuators 51 and 52 are realized as only passive devices. Therefore, the number of devices used can be reduced. The BPF 10 filters signals transmitted and received via an antenna to pass only signals in a selected frequency band.

[23] The passive IRM 20 up-converts signals to be transmitted or down-converts received signals, and removes image frequencies deteriorating signal characteristics to minimize a conversion loss and a noise. The passive IRM 20 according to an embodiment can reduce a conversion loss to 0.92 dB or less.

[24] Referring to Figs. 1 and 2, the passive IRM 20 includes a Balun circuit unit 23, a first mixer 21, and a second mixer 22.

[25] The Balun circuit unit 23 includes first, second, third, fourth, fifth, and sixth capacitors Cl, C2, C3, C4, C5, and C6, and first, second, third, fourth inductors Ll, L2, L3, and L4.

[26] A first node 231 of the Balun circuit unit 23 is connected to the BPF 10, and a second node 232 is grounded. Also, a third node 233 and a fourth node 234 are connected to the first mixer 21 and the second mixer 22, respectively.

[27] The Balun circuit unit 23 converts balanced signals into unbalanced signals, and converts unbalanced signals into balanced signals.

[28] The Balun circuit unit 23 separates received signals into I-received signals and Q- received signals, or synthesizes transmission signals using I-transmission signals and Q-transmission signals.

[29] The first and second mixers 21 and 22 mix oscillating frequency signals input from the VCO 30 with I-received signals and Q-received signals to convert the signals into baseband signals, or mix oscillating frequency signals input from the VCO 30 with I- transmission signals and Q-transmission signals to convert the signals into RF signals.

[30] In an embodiment, each of the first mixer 21 and the second mixer 22 is formed using four n-channel metal oxide semiconductors (NMOSs) Tl to T4 or T5 to T8. Oscillating frequency signals of the VCO 30 is input to a gate terminal of each NMOS transistors.

[31] The first and second mixers 21 and 22 are connected to a fifth node 235 and a sixth node 236. The fifth node 235 is connected to the first LPF 41. The sixth node 236 is connected to the second LPF 42.

[32] Meanwhile, the BPF 10 and the passive IRM 20 operate in an RF signal band. The first LPFs 41 and 42, the first and second attenuators 51 and 52, the switching unit 60, the first and second amplifiers 71 and 72, the third and fourth LPFs 81 and 82, and the first and second driving amplifiers 91 and 92 operate in a baseband.

[33] The VCO 30 provides oscillating frequency signals to the first and second mixers 21 and 22. Though not shown, the VCO 30 receives variable and stable oscillating frequency signals from a phase synchronization circuit including a temperature compensated crystal oscillator (TCXO).

[34] A baseband signal processing unit includes the first and second LPFs 41 and 42, and the first and second attenuators 51 and 52. The baseband signal processing unit is located between the IRM 20 and the switching unit 60 to filter or attenuate signals in a baseband.

[35] The first and second LPFs 41 and 42 remove out-band noises of baseband signals output from the passive IRM 20 and disturbing signals, and reduce influences of discrimination noises from transmission signals.

[36] The first and second attenuators 51 and 52 control the intensities of signals input from the first and second LPFs 41 and 42, and signals input from the first and second driving amplifiers 91 and 92.

[37] The first and second attenuators 51 and 52 may be power-consuming devices such as resistors, and are designed to attenuate power to a desired degree.

[38] For example, RF signals can be received with power intensity of about -10 to -100 dBm. The first and second attenuators 51 and 52 attenuate signals of a strong electric field such that the signals are not saturated at an amplifier, and controls an attenuation degree in case of signals of a weak electric field such that the signals are not attenuated to a reference value or less.

[39] Also, the first and second attenuators 51 and 52 may be semiconductor type attenuators or switch type attenuators. The semiconductor type attenuators control an attenuation amount continuously in an analog manner by controlling a bias of a semi- conductor device such as a transistor. The switch type attenuators control an attenuation amount by switching to a fixed attenuating circuit and a through circuit.

[40] The switching unit 60 switches a transmission path and a reception path to selectively pass reception signals and transmission signals.

[41] I- transmission signals and Q-transmission signals are delivered to the first and second attenuators 51 and 52, or I-reception signals and Q-reception signals are delivered to the first and second amplifiers 71 and 72 depending on the operation of the switching unit 60.

[42] The switching unit 60 can be provided as a single pole double throw (SPDT) device.

The SPDT device is a kind of an integrated circuit (IC) switching device, and operates up to about 3 GHz at direct current (DC) voltages of two positive control voltages. The SPDT device can be opened/closed at a very low control voltage of 2.4 V.

[43] A reception signal processing unit includes the first and second amplifiers 71 and 72, and the third and fourth LPFs 81 and 82. The reception signal processing unit is located between the switching unit 60 and a demodulating unit (not shown) to amplify or filter signals in the baseband.

[44] The first and second amplifiers 71 and 72 receive I-reception signals and Q-reception signals and amplify the received signals with low noises. The first and second amplifiers 71 and 72 are controlled by receiving an automatic gain control signals from a baseband demodulating unit.

[45] Since the first and second amplifiers 71 and 72 operate in the baseband, they have relieved requirement gain and noise characteristics compared to those of an amplifier operating in an RF band.

[46] The third and fourth LPFs 81 and 82 finally filter I-reception signals and Q-reception signals input from the first and second amplifiers 71 and 72 before digitalization.

[47] A transmission signal processing unit includes the first and second driving amplifiers

91 and 92. The transmission signal processing unit is located between the switching unit 60 and a modulating unit (not shown) to amplify signals in the baseband.

[48] The first and second driving amplifiers 91 and 92 amplify I- transmission signals and

Q-transmission signals.

[49] A signal processing apparatus according to an embodiment reduces the number of devices operating in the RF band to reduce power consumption and achieve a simple circuit design.

[50] Also, a signal processing apparatus according to an embodiment increases the number of devices having a bi-directional operation characteristic, so that the size of the signal processing apparatus can reduce and a structure thereof can be simplified.

[51] Also, a signal processing apparatus according to an embodiment reduces the number of active devices to reduce power consumption. [52] Also, a signal processing apparatus according to an embodiment can up-convert transmission signals and down-convert reception signals using a single IRM.

[53] Also, since a signal processing apparatus according to an embodiment does not use a low noise amplifier or a power amplifier in the RF band, a device such as a load inductor is not required. Accordingly, in the case where an application-specific integrated circuit (ASIC) is applied, the size of the signal processing apparatus can be remarkably reduced.

[54] Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims.

[55] For example, elements described in detail in the embodiment of the present disclosure can be modified, and differences associated with these variations and modifications should be construed to be included in the scope of the present disclosure defined by the appended claims. Industrial Applicability

[56] A signal processing apparatus according to an embodiment can be applied not only to mobile communication terminals but also to near field radio communication systems.

Claims

[1] A signal processing apparatus comprising: an image rejection mixer up-converting transmission signals and down- converting reception signals; an oscillator for providing oscillation frequency signals to the image rejection mixer; a switching unit connected to the image rejection mixer to switch a transmission path and a reception path to selectively pass transmission signals and reception signals; and a transmission signal processing unit and a reception signal processing unit connected to the switching unit to process transmission signals and reception signals, respectively.

[2] The signal processing apparatus according to claim 1, comprising a band pass filer for filtering transmission signals and reception signals connected in front of the image rejection mixer.

[3] The signal processing apparatus according to claim 1, wherein the image rejection mixer comprises: a Balun circuit unit for separating reception signals into I-reception signals and Q-reception signals, and synthesizing transmission signals using I-transmission signals and Q-transmission signals; and a first mixer and a second mixer for mixing oscillating frequency signals input from the oscillator with the I-reception signals and Q-reception signals to down- convert the signals and for mixing oscillating frequency signals with the I- transmission signals and Q-transmission signals to up-convert the signals.

[4] The signal processing apparatus according to claim 1, wherein the image rejection mixer comprises only passive devices.

[5] The signal processing apparatus according to claim 1, wherein the image rejection mixer comprises an inductor, a capacitor, and a transistor only.

[6] The signal processing apparatus according to claim 1, comprising first and second low pass filters between the image rejection mixer and the switching unit.

[7] The signal processing apparatus according to claim 1, comprising first and second attenuators between the image rejection mixer and the switching unit.

[8] The signal processing apparatus according to claim 1, wherein the reception signal processing unit comprises first and second amplifiers operating in response to an automatic gain control signals.

[9] The signal processing apparatus according to claim 1, wherein the transmission signal processing unit comprises first and second driving amplifiers.

[10] The signal processing apparatus according to claim 1, wherein the image rejection mixer has a bi-directional operating characteristic.

[11] A signal processing apparatus comprising: an image rejection mixer up-converting transmission signals and down- converting reception signals; an oscillator for providing oscillation frequency signals to the image rejection mixer; a baseband signal processing unit connected to the image rejection mixer to amplify and/or attenuate transmission signals and reception signals in a baseband; a switching unit connected to the baseband signal processing unit to switch a transmission path and a reception path to selectively pass transmission signals and reception signals; and a transmission signal processing unit and a reception signal processing unit connected to the switching unit to process transmission signals and reception signals, respectively.

[12] The signal processing apparatus according to claim 11, wherein the baseband signal processing unit comprises a low pass filter and an attenuator.

[13] The signal processing apparatus according to claim 11, wherein the image rejection mixer comprises only passive devices and the switching unit.

[14] The signal processing apparatus according to claim 11, comprising a band pass filer for filtering transmission signals and reception signals connected in front of the image rejection mixer.

[15] The signal processing apparatus according to claim 11, wherein the image rejection mixer comprises: a Balun circuit unit for separating reception signals into I-reception signals and Q-reception signals, and synthesizing transmission signals using I-transmission signals and Q-transmission signals; and a first mixer and a second mixer for mixing oscillating frequency signals input from the oscillator with the I-reception signals and Q-reception signals to down- convert the signals and for mixing oscillating frequency signals with the I- transmission signals and Q-transmission signals to up-convert the signals.

[16] The signal processing apparatus according to claim 11, wherein the image rejection mixer comprises an inductor, a capacitor, and a transistor only.

[17] The signal processing apparatus according to claim 11, wherein the image rejection mixer and the baseband signal processing unit comprise a bi-directional operating characteristic.

[18] The signal processing apparatus according to claim 11, wherein the transmission signal processing unit comprises first and second driving amplifiers. [19] The signal processing apparatus according to claim 11, wherein the reception signal processing unit comprises first and second amplifiers operating in response to automatic gain control signals. [20] The signal processing apparatus according to claim 11, wherein the image rejection mixer comprises a Balun circuit unit, a first mixer and a second mixer, and wherein the Balun circuit unit comprises a first node connected to an antenna, a grounded second node, and capacitors and inductors connected to the first and second nodes, and wherein the first and second mixers being connected to the Balun circuit unit and comprising a plurality of transistors inputting oscillating frequency signals of an oscillator to a gate terminal.