This Application claims priority of Taiwan Patent Application No. 96143435, filed on Nov. 16, 2007, the entirety of which is incorporated by reference herein.
1. Field of the Invention
The invention relates to wireless communications, and in particular, to a wireless communication module having matching networks implemented on a Low-Temperature Cofired Ceramics (LTCC) substrate.
2. Description of the Related Art
In conventional architecture, impedance mismatch between the BPF 116 and the mixer 120 may degrade quality of signal transmission, thus, conventionally, a matching network 118 is deployed between the BPF 116 and the mixer 120 to compensate for impedance mismatch. The same problem occurs between the BPF 116 and LNA 104, so a matching network 114 is also required to match their impedances. Generally speaking, impedance mismatch exists between any two elements in the RF modules 115a to 115n, so matching networks are essential components in such an architecture.
In the receiver 110a, all the RF modules 115a to 115n are deposited on the surface of a PCB 111 using discrete components. The PCB 111 may be a multi-layered structure such as FR4. Due to natural limitations of materials, when all components are deposited together, circuit complexity, weight and area size are increased, and consequently, system stability and performance are influenced. As market requirements continue to trend toward more compact and light weighted products, the area size issue for a PCB 111 has become a technical bottleneck to be solved.
Additionally, a matching network is typically formed by inductors and capacitors which are market offered components, and only specific parameters are available. A matching network implemented by the components of specific parameters is not flexible enough to fully compensate various impedance mismatches. For these reasons, an enhanced architecture for a circuit board is desirable.
An exemplary embodiment of a wireless communication module is implemented based on an LTCC substrate comprising at least first and second layers. First and second communication units are deposited at the first layer, and a matching network is deposited at the second layer, coupled to the first and second units to match impedances therebetween. In this way, signals are correctly transmitted to and from the first and second communication units. The first layer is at the surface of the LTTC substrate, and the second layer is at a depth inside the LTCC substrate. The matching network comprises at least an inductor or a capacitor embedded in the second layer.
In one embodiment, the first and second communication units are selected from an LNA, a bandpass filter and a down conversion mixer. Alternatively, the first and second communication units may be selected from a power amplifier, a bandpass filter and an up conversion mixer.
Another embodiment provides a wireless communication device, employing the same structure, comprising a plurality of receivers coupled to the antenna. At least one of the receivers is deposited on the LTCC substrate, comprising a plurality of RF modules each associated with a channel, and one of the RF modules comprises a first communication unit and a second communication unit deposited at the first layer, and a matching network deposited at the second layer.
Further embodiments are transmitters and receivers employing the same structure. A detailed description is given in the following embodiments with reference to the accompanying drawings.
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
a shows an embodiment of a matching network 410; and
b shows an embodiment of a matching network 420.
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
Low-Temperature Cofired Ceramics (LTCC) is a substrate material for circuit boards with electrodes made by silver, gold or copper. Passive elements such as capacitor, resistors, filters, matching networks and couplers can be buried inside the LTCC substrate using a parallel printed coating process in a 900 degrees centigrade debinding oven to organize an integrated ceramic product.
LTCC technologies have been widely adopted because ceramic has similar material features with silicon, and is particularly suitable to be combined with integrated circuits. Area size is significantly reduced as well as the costs, and passive components are buried in a three-dimensional high density structure, so the modules made therefrom can be easily packaged. LTCC integrated components can be flexibly made into various substrate based or active/passive component embedded products, so the applicable product type covers a wide range comprising component, substrate or module. Because the LTCC substrate uses ceramic as the dielectric material which features high-Q and high frequency range, it is particularly adaptable for high frequency communication applications.
In each of the receivers, there may be more than one RF modules for handling signals from different channels. As an example, the receiver 210a may comprise four RF modules 215a to 215d, and a channel switch 112 selectively enabling one of the RF modules to receive RF signals from the system switch 106. The channel switch 112 may not be an essential component in the embodiment, and the four RF modules may be able to operate concurrently. The RF modules 215a to 215d are made by LTCC substrates. Specifically, all the RF modules 215a to 215d may be deposited on one LTCC substrate. The LTCC substrate comprises at least two layers, the surface 221 and a depth inside 222. General communication components such as an LNA 104a, BPF 216a and mixer 218a are deposited on the surface 221, and all the matching networks 212a and 214a are buried in the depth inside 222. The matching network 212a is dedicated to compensate impedance mismatches between the LNA 104a and the BPF 216a, and the matching network 214a is particularly adapted between the BPF 216a and the mixer 218a. The communication components are not limited by
As to the transmitters, there may also be a plurality of RF modules implemented in one transmitter. As an example, the transmitter 230a comprises a plurality of RF modules 225a to 225d, each handling a different channel. In some applications, the transmitter 230a may use an RF switch 113 to selectively enable one of the RF modules 225a to 225d and output an outbound RF signal sent therefrom. Based on the LTCC structure, all the RF modules 225a to 225d are deposited on the same LTCC substrate, with components individually deposited at a surface 251 and a depth inside 252. General communication components such as a power amplifier 105a, BPF 236a and mixer 238a are deposited on the surface 251, and all the matching networks 232a and 234a are buried in the depth inside 252. In the embodiment, the matching network 232a is designed to match impedances between the power amplifier 105a and the BPF 236a, and the matching network 234a is designed to match impedances between the BPF 236a and the mixer 238a.
a shows an embodiment of a matching network 410. In the depth insides 222 and 252 as shown in
b shows an embodiment of a matching network 420. The matching network 420 is a differential pair, particularly applicable for the matching network 214a and 234a deposited in the depth insides 222 and 252 of
The major concept of the invention is to bury matching networks of RF modules into the LTCC substrate of a wireless communication device, such that components on the surface can be overlapped to reduce area size. Based on the architecture, parameters of matching networks can be accurately implemented as required, surpassing the limitations of conventional fixed value components. Accuracy is efficiently increased while cost is significantly reduced. Although the embodiment in
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Number | Date | Country | Kind |
---|---|---|---|
96143435 | Nov 2007 | TW | national |