Design of Si-Based Distributed Amplifiers for Microwave and Millimeter-Wave Applications
Date Issued
2010
Date
2010
Author(s)
Chen, Ping
Abstract
With the development of communication technologies, RF integrated circuits move toward higher frequencies, wider bandwidth. In wideband systems, such as optical communication and ultra-wide band (UWB) communication, circuits with low cost, wide bandwidth and flat frequency response are required. The distributed configurations extensively find applications in the realization of wideband amplifiers. The basic operation and fundamental principles of the conventional distributed amplifier are reviewed. On the other hand, the development of the distributed amplifier in the recent years is discussed, and the advantages and disadvantages among the different topologies of distributed amplifiers are compared.
Two distributed amplifiers using standard 0.18-μm CMOS technology were implemented and measured. The first one is a distributed amplifier with a bandwidth of 35 GHz. In order to resolve the trade-off among the gain, output power and noise figure in present topologies, a new topology is proposed. The topology is the combination of conventional distributed amplifier (CDA) and cascaded single-stage distributed amplifier (CSSDA), and it let wideband amplifier give considerations to the gain, output power and noise figure simultaneously. From the measurements, the distributed amplifier has a small signal gain of 20.5 dB, a 3-dB bandwidth of 35 GHz, and a gain-bandwidth product of 371 GHz. The maximum output 1-dB compression point (OP1dB) is 8.5 dBm and the noise figure is between 6.8 dB and 9.3 dB from 5 to 26 GHz. The chip size including testing pads is only 0.78 mm2, and the ratio of the gain-bandwidth to chip size achieves 476 GHz/mm2. To our knowledge, the circuit has the highest ratio of gain-bandwidth product to chip area and the highest figure of merit (FOM) in 0.18-μm CMOS, and it has a comparable performance with other advanced process.
The second amplifier is a distributed amplifier using high-pass transmission lines, and its designed band is 22-29 GHz. Due to the symmetry of the circuit, the distributed amplifier has two paths to amplify the signals. When the distributed amplifier is used in bi-directional system, it can achieve the characteristic of amplifier reuse. The characteristic is important in phase array which requires many elements for high data rate communication. In contrast with conventional distributed amplifier used in bi-directional system, the amplifier does not need extra drain bias circuits since they are a part of the distributed amplifier. Hence, the chip size is smaller by using this approach. The core area is only 0.17 mm2 in this design. From the measurements, the distributed amplifier has a maximum saturation output power of 12 dBm, a maximum OP1dB of 6.5 dBm, and a small signal gain of 6.4 dB with only 0.2-dB difference in the two directions.
Subjects
wideband amplifier
distributed amplifier (DA)
complementary metal-oxide-semiconductor (CMOS)
monolithic microwave integrated circuit (MMIC)
composite right/left-handed transmission line (CRLH-TL)
bi-directional system
Type
thesis
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