Abstract: An oscillator which is used for a portable telephone or the like, comprises a transistor fabricated by MOS process, and entails a low level of noise other than the desired oscillation frequency. The oscillator includes quartz oscillating element 1 and a first amplifier 3 connected between input terminal 4 and output terminal 2. The first amplifier 3 has a first P-type transistor 11 and a first N-type transistor 12 both fabricated by MOS process. A gate 23 of the first P-type transistor 11 spans between a P-type source diffused region 22 and a P-type drain diffused region 21. A gate of the first N-type transistor 12 spans between an N-type source diffused region 18 and an N-type drain diffused region 19. The span of the gate 20 of the first N-type transistor 12 is longer than that of the gate 23, and the field strength is low, thereby lowering the noise level other than the oscillation frequency.

Abstract: A control circuit includes: a temperature 30; a temperature sensing section 32; a memory 36, an amplifying section 31 to which the memory and the temperature sensor are electrically connected; a first D/A converting section 38 electrically interposed between the memory and the temperature sensing section; a second D/A converting section electrically interposed between the memory and the amplifying section 31, The amplifying section 31 includes: a polarity inverting circuit 33 connected to the temperature sensor; and a variable attenuator 34, an offset adjusting circuit 100, and an amplifying circuit 35 that are connected sequentially to the polarity inverting circuit. The amplifying section 31 is connected to a sample hold circuit 41 through a displacement buffering means 101. The memory has 8 or less working control voltage setting groups.

Abstract: A crystal oscillation apparatus and a method of adjusting the same, comprising a crystal oscillating circuit, a frequency adjusting element coupled with the crystal oscillating circuit, and a control circuit for controlling voltage to be applied to the frequency adjusting element. The control circuit comprises a temperature sensor, a temperature detecting section coupled with the temperature sensor, a memory device coupled with the temperature detecting section, an amplifier to which the memory device and the temperature sensor are coupled, a first D/A converter between the memory device and temperature detection section, and a second D/A converter between the memory device and amplifier. The memory device has no more than 8 control voltage setting groups. Each of the control voltage setting groups has temperature detection data, amplitude setting data and offset voltage data.