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News Release

August 27, 1998

Hitachi Releases The HVC376B VCXO Variable-Capacitance Diode Achieving High Capacitance Change Ratio and Low Loss

- Low-voltage VCXO unit drive plus lower noise of oscillation unit through approximately 30% increase in capacitance change ratio and 50% reduction in series resistance compared with previous Hitachi products -

Hitachi, Ltd.(NYSE:HIT) today announced the release of HVC376B as a low-voltage-drive type variable-capacitance diode for VCXOs*1 used for reference oscillation in PDC, GSM, and similar portable telephones. The HVC376B features high capacitance change ratio and low series resistance. Sample shipments will begin in September 1998 in Japan.

Use of Hitachi's super shallow PN junction process*2 and optimization of the process conditions have resulted in an approximately 30% increase in capacitance change ratio (actual value: C1/C4 = 4.8) and an approximately 50% reduction in series resistance (1.5 to 0.8 compared with Hitachi's previous HVC359, offering low-voltage VCXO unit drive plus lower noise of oscillation unit.

With the continuing decrease in voltage and power consumption in portable telephones, VCXO variable-capacitance diodes are also required to offer a higher capacitance change ratio to enable large variations in the oscillation frequency within a low voltage zone and with a narrow voltage variation range, and lower loss to further reduce the noise of oscillation unit. However, as the capacitance change ratio is raised, series resistance also increases.

Use of Hitachi's super shallow PN junction process for the new HVC376B made possible a major improvement in both capacitance change ratio and series resistance, factors which involve a mutual tradeoff. In addition, capacitance temperature drift has been drastically reduced to 60 ppm/degree Celcius in the low-voltage zone, enabling stable operation to be achieved. These features make it possible to improve the performance and design margins of the oscillation unit, and so improve the performance of PDC, GSM, or other portable telephones themselves.

At the same time, process improvements have also been implemented and capacitance dispersion within the wafer has been improved, resulting in a reducing of capacitance deviation by 30% compared with previous Hitachi products. This reduction in deviation will contribute to smooth startup in the design stage and the transition to mass production, and stable production once mass production has started.

Other suitable HVC376B applications aside from VCXOs include VCO units requiring low-voltage operation and variable band-pass filters.

Hitachi plans to extend the product lineup with the development of low-frequency products (with a C1 capacitance value of around 50 pF) and GHz-band low- capacitance products (with a C1 value of around 5 pF) in line with users' needs.

Notes:

1.VCXO: Voltage controlled crystal oscillator.

2.Super shallow PN junction process: A diode PN junction process developed by Hitachi. A submicron junction depth is achieved by use of a lower temperature and impurity density optimization during junction formation.

Typical Applications

  • VCXO units
  • VCO units
  • Variable band-pass filters

Price in Japan

Product Name

Sample Price (yen)

HVC376B

12

Features

  1. High capacitance change ratio at low voltage (C 1/C4 > 4.3) A high capacitance change ratio enables a wide variable frequency range to be obtained in a low and narrow operation voltage range.
  2. Low series resistance (rS < 0.8 ) Low series resistance enables lower noise of oscillation unit.
  3. Low capacitance temperature drift ( 60 ppm/degree Celcius for 1V capacitance) Capacitance does not vary greatly with temperature, enabling stable operation to be achieved.
  4. 30% narrower capacitance specification than previous product Makes it possible to reduce adjustment steps on the production line, improve yield, and reduce costs.

Specifications
1. Absolute Maximum Ratings (Ta = 25 degrees Celcius)

Item
Symbol
Value
Unit

Reverse voltage
VR
15
V

Junction temperature
Tj
125
degree Celcius

Storage temperature
Tstg
-55 to +125
degree Celcius

2. Electrical Characteristics (Ta = 25 degrees Celcius)

Item
Symbol
Min
Max
Unit
Test Conditions

Reverse current
IR1
-
10
nA
VR=10V

IR2
-
100
VR=10V,Ta=60 degree Celcius

Inter-pin capacitance
C1
25.0
28.5
pF
VR=1V, f=1MHz

C4
4.8
6.8
VR=4V, f=1MHz

Capacitance change ratio
n
4.3
-
-
C1/ C4

Series resistance
rS
-
0.8
VR=1V, f=470MHz

WRITTEN BY Secretary's Office
All Rights Reserved, Copyright (C) 1998, Hitachi, Ltd.