Nippon Precision Circuits (NPC)^* has developed the industry's first BiCMOS ICs for crystal resonator that operates at the maximum frequency of 165 MHz and at a voltage as low as 1.8 V. These ICs, the CF5035 series, are intended for applications in network-related equipment and delivery of their samples has been started.

The CF5035 series is a collection of ICs for crystal oscillator that oscillates at a maximum frequency of 165 MHz, operating at a voltage as wide as 1.6 to 3.6 V. Therefore, these ICs can be used with a 1.8-V power supply, as well as the 2.5-V and 3.3-V power supplies. The oscillation frequency is 70 MHz to 165 MHz at 1.8 V, and 70 MHz to 220 MHz at 2.5 V or 3.3 V. In addition, the third overtone oscillation and fundamental wave can be oscillated over the entire frequency and voltage ranges. As the oscillation circuit, a Colpitts oscillator is employed, and an oscillation capacitor and a feedback resistor necessary for crystal oscillation are provided. The oscillation circuit is a bipolar circuit that can perform stable crystal oscillation in a wide voltage range. A CMOS output buffer circuit is used as the output buffer that can drive a load capacitance of 15 pF. Integrating an oscillator circuit and an output buffer on a single chip, the CF5035 employs NPC's original BiCMOS process. This allows the CF5035 series to provide a high-frequency crystal oscillator circuit of the SMD type that is intended for network-related equipment.

In network-related equipment that backs up the broadband networked society of today, a high-frequency crystal oscillator is a key component as the stable clock source of a system. Semiconductor devices used in this equipment and systems have been increasingly dense and power-saving to lower the heat and power consumption which has tended to increase as the operating speed of the equipment and system increases. Consequently, crystal oscillator ICs have increasingly been demanded to consume as little power as possible. This allows them to be used with low-voltage devices to which the clock output by these ICs is to be input, and that the power consumption of a crystal oscillator that consumes more power than the other electronic components can be reduced. However, crystal oscillators, especially high-frequency models, that have conventionally been used as the clock sources of network equipment have been difficult to oscillate at 1.8 V. Therefore, 3.3-V crystal oscillators have been used. To satisfy the market demand for a crystal oscillator that can operate at 1.8 V, NPC has developed the industry's first ICs for high-frequency oscillators, the CF5035 series. In developing these ICs, NPC made its utmost efforts to stabilize oscillation of a crystal oscillator operating at as high as 100 MHz with a voltage of as low as 1.8 V. As a result, a crystal oscillator employing the CF5035 series can stabilize the operation of the application devices and systems as their clock source.

Major features of the CF5035 series
1.	Oscillation at frequency of as high as 165 MHz at a voltage of as low as 1.8 V
2.	Wide operating voltage range covering 1.8 V, 2.5 V, and 3.3 V A Colpitts oscillator using bipolar transistors realizes an oscillation frequency of as high as 165 MHz at a voltage of as low as 1.8 V. The CF5035 series can lower the supply voltage of a crystal oscillator and, at the same time, reduce the power consumption, heat generation, and radiation, thanks to employment of bipolar transistors. The circuits of these oscillator ICs are designed so that they can operate in a voltage range of as wide as 1.6 to 3.6 V with stability, and that they can be used with a 1.8-V, 2.5-V, or 3.3-V power supply.
3.	Integrating a high-frequency bipolar oscillator circuit and a high-frequency CMOS buffer output circuit on a single chip NPC's original BiCMOS process has realized integration of a high-frequency oscillator circuit and an output buffer circuit on a single chip. A CMOS output buffer that can operate at high frequencies is employed as the output buffer, so that a 15-pF capacitive load can be driven.

NPC plans to expand the lineup of its crystal oscillator IC products by promoting product development, so that wide range of applications of crystal oscillator can be covered.

^* : Main office: 2-4-3 Fukusumi, Koto-ku Tokyo, President: Yoshifumi Gomi