The new SiGe:C HBT is a transistor that amplifies a weak microwave signal received wirelessly to an appropriate level and achieves a noise figure of 0.75 decibel (dB), which is the industry's top level for the 5.8 gigahertz (GHz) band used by wireless LANs and other applications. The fact that it amplifies with such low noise means that it can increase communication sensitivity in end products. Since it can reduce signal transmission errors, it can achieve operating power consumption as low as one-quarter of that of Renesas’ existing products while maintaining equivalent performance.
Renesas sells transistors and ICs for microwave amplifier applications, provides solutions for wireless LANs, consumer cordless phones for the home, terrestrial digital TV broadcast tuners, and equipment that includes GPS functionality. It has achieved the industry's top market share (Renesas' estimate) for microwave application transistors. Within this context, Renesas has developed a new process technology that uses SiGe:C materials to respond to market needs for even lower noise and to provide solutions for the 12 GHz and higher frequencies used in satellite broadcasting. Based on this process, Renesas has developed and is now releasing the NESG7030M04 SiGe:C HBT device that achieves both the industry's best low-noise performance as well as stable performance over a wide frequency range from a few MHz to the 14 GHz band.
(1) The industry's best low-noise performance in the 5.8 GHz band
By applying this newly-developed SiGe:C process (see Note 3), Renesas’ 5.8 GHz band SiGe:C HBT and SiGe HBT devices achieve the industry's lowest noise level of 0.75 dB. This is an improvement of 0.35 dB over earlier Renesas SiGe HBT devices. Also, this device achieves a gain at the minimum noise level of 14.0 dB. This allows communication sensitivity to be increased and signal transmission errors to be reduced, and the new device can achieve equivalent performance to earlier Renesas products at 1/4 of the power consumption.
(2) Increased withstand voltage for stable operation over a wide bandwidth
In earlier silicon-based heterojunction bipolar transistors, it was not possible to avoid a reduction in the collector-emitter withstand voltage in exchange for reducing noise, and this limited the range of applications for which these devices could be used. In this new product, Renesas has optimized the collector-base profile, making it possible to guarantee a withstand voltage rating of 4.3 V. This increases the range of supply voltages that can be used and enables stable operation over a wide frequency range, from a few MHz to the 14 GHz band. This makes it possible to use this device in a wider range of applications. For example, it can support all ISM band (see Note 4) applications, including smart grid, smart meter, and home area network (HAN) applications.
Furthermore, since this transistor was developed for microwave applications, Renesas provides it in an industry standard 4-pin thin-form mini-moulded package (for which the Renesas package name is M04). As a result, this product can contribute to a reduction in manufacturing steps in end user products. Examples include simplifying the mounting evaluation process due to the track record of existing packages; and using an existing circuit board pattern and slightly modifying the surrounding circuits.
At the same time as expanding its product line of bipolar transistors with the industry's best low-noise performance by taking advantage of this new process, Renesas is also committed to deploying this new process in the development of microwave ICs and providing further solutions in this area to respond to market needs.
Note 1: This is an fT = 100 GHz process that combines the Renesas SiGe:C heterojunction bipolar transistor and a 0.15 µm CMOS process and is optimized for microwave IC applications.
BiCMOS: Bipolar complementary metal oxide semiconductor. This is a process that can manufacture mixed bipolar and CMOS devices. It can be used to manufacture microwave application ICs by combining the bipolar technology that is optimal for high-frequency circuits and CMOS technology that supports high-density, low-power circuit design.
Renesas positions this process as the next generation following the Renesas process, which Renesas has been using up to now. Renesas is committed to continuing its process development efforts.
Note 2: The silicon-germanium: carbon heterojunction bipolar transistor (SiGe:C HBT) is a transistor optimised for microwave applications. It is implemented by combining a process technology that improves device performance (with the addition of small amounts of germanium and carbon to the silicon transistor base) with a process that forms electron paths that allow high-speed transport at high density in the semiconductor using heterojunctions.
Note 3: Application of the SiGe:C process to this new product
To aim for lower noise in the microwave range, Renesas has worked to increase electron speed in the base and reduce the base resistance by optimizing its 0.15 µm fine fabrication technology and by using a newly-developed SiGe:C process with optimized selective epitaxial crystal growth technology that reduces the base resistance of the transistor (which has an emitter, base, and collector structure) by about 60%.
Epitaxial growth: a process technology that limits crystal growth in the semiconductor to just the section that becomes the transistor's base layer.
Note 4: ISM: Industrial, scientific and medical band. The ISM is a band of frequencies allocated for general-purpose use by the industrial, scientific, and medical fields. Wireless systems that use this band include wireless LANs, Bluetooth, amateur radio, DSRC, various types of radar, cordless telephones, ZigBee, and other applications.