Ideally, the output signal is of constant amplitude with no variation in frequency. Actually, something less than this is usually obtained. The degree to which the ideal is approached depends upon such factors as class of amplifier operation, amplifier characteristics, frequency stability, and amplitude stability. Sine-wave generators produce signals ranging from low audio frequencies to ultrahigh radio and microwave frequencies. Many low-frequency generators use resistors and capacitors to form their frequency-determining networks and are referred to as RC Oscillators. They are widely used in the audio-frequency range. Another type of sine-wave generator uses inductors and capacitors for its frequency-determining network. This type is known as the LC Oscillator. LC Oscillators, which use tank circuits, are commonly used for the higher radio frequencies. They are not suitable for use as extremely low-frequency oscillators because the inductors and capacitors would be large in size, heavy, and costly to manufacture. Sine wave oscillators are useful in applications like audio signal generation, reference signals for different applications and in measurement applications. To vary the frequency of a traditional RC filter based sine-wave oscillator, you should generally use a pair of ganged variable resistors, and you should thoroughly match their characteristics over the entire variation range to satisfy the oscillator's balancing conditions. This restriction leads to problems in the tuning range and high cost, thereby limiting the range of applications.