VAR
Vishay Foil Resistors
Ultra High Precision, Z-Foil Audio Resistor Minimizes Noise and
Distortion in the Signal Path with TCR of ± 0.05 ppm/°C, Tolerance
to ± 0.005 % and High Linearity or Low Voltage Coefficient of
Resistance (VCR) of 0.1 ppm/V
FEATURES
Temperature coefficient of resistance (TCR):
± 0.05 ppm/°C typical (0 °C to + 60 °C,+ 25 °C
ref.) ± 0.2 ppm/°C typical (0 °C to + 125 °C,
+ 25 °C ref.)
INTRODUCTION
Many manufacturers and users of precision electronic
equipment suffer needlessly from unexplained instabilities
and drifts due to noise effects. They resign themselves to
making constant adjustments and troubleshooting. But in
fact these can be avoided. Instability is often traceable to a
few supposedly “fixed” resistors which are not really fixed at
all. If these resistors would only retain their original values,
there would be no need for costly controls and other
compensating circuitry. That’s why the only resistor for
applications such as these is Vishay Bulk Metal® Foil. In
high-end audio equipment, careful selection of resistors is
one of the best ways to avoid or minimize noise and
distortion in the signal path. Noise is an unwanted wide
spectrum signal that may be superimposed on any useful
signal, including DC. Resistors, like other passive
components, are noise sources to various degrees,
depending upon resistance value, temperature, applied
voltage, and resistor type. Many experiments have been
done to show why some resistors are “noisier” than others.
But the only test that audio experts and audiophiles have
agreed on is comparing the level of fidelity that results when
different resistor technologies are used in actual audio
systems.
High-end analog audio applications require low intrinsic
noise, high linearity of amplification, and minimal dynamic
distortion. The typical audio amplifier consists of a voltage
preamplifier (preamp) and power amplifier (final driver). The
voltage preamplifier deals with low-level signals. That is why
its intrinsic noise level is critical. Resistors are among the
principal noise sources in the amplifiers. The main
requirements for the audio power amplifier are high linearity
of amplification and minimal dynamic distortion. Vishay Foil
resistors are characterized by very low intrinsic non-linearity
of the resistive element, which is made from cold-rolled bulk
metal.
The VAR, composed of Vishay’s Bulk Metal® Z-foil
technology, with improved sound quality, provides a
combination of low noise and low inductance/capacitance,
making it unrivalled for applications requiring low noise and
distortion-free properties.
Document Number: 63140
Revision: 03-Jan-12
Rated power: to 0.4 W at + 70 °C
Resistance tolerance: to ± 0.01 % (0.005% is available)
Load life stability: to ± 0.005 % at 70 °C, 2000 h at rated
power
Resistance range: 10 to 100 k
"Naked Z-foil resistor" design without molding or
encapsulation adds an additional dimension for reducing
signal distortion and increasing clarity in signal processing.
Vishay Foil resistors are not restricted to standard values;
specific "as-required" values can be supplied at no extra
cost or delivery (e.g. 1K2345 vs 1K)
Electrostatic discharge (ESD) at least to 25 000 V
Non-inductive, non-capacitive design
Rise time: 1 ns, effectively no ringing
Current noise: 0.010 µV (RMS)/Volt of Applied Voltage
(< - 40 dB)
Thermal EMF: 0.05 µV/°C
Voltage coefficient: < 0.1 ppm/V
Thermal stabilization time < 1 s (nominal value achieved
within 10 ppm of steady state value)
Inductance: < 0.08 µH typical
The Z-Foil chip in the VAR has been especially treated to
increase load life stability.
Terminal Finish: lead (Pb)-free or tin/lead alloy(1)
Prototype quantities available in just 5 working days or
sooner. For more information, please contact
foil@vishaypg.com
For better performances please contact us.
For any questions, contact: foil@vishaypg.com
www.vishayfoilresistors.com
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