A low noise clock oscillator in modular form to plug into a standard 14 or 8 pin DIP clock oscillator socket on the motherboard of a host device to retrofit the host device without redesign of the host device motherboard so that the host device can reduce its EMC emissions sufficiently to pass EMC emission tests. The oscillator is characterized by use of a spread spectrum clock generator, EMC filters between the clock generator and the Vcc, ground and clock bus coupling points to the motherboard and a single point ground connection to the motherboard. This oscillator module allows an easy retrofit to a host device that has already been designed to substantially lower EMC emissions that can be traced to the clock by as much as 20 dB without expensive, time consuming redesign efforts to add shielding, more grounds and possibly reroute the motherboard traces.

A piezoelectric oscillator in which a resonator accommodating a piezoelectric element, such as a quartz crystal resonator or a SAW resonator, in a case thereof and an IC chip, such as an IC for PLL, electrically connected to the resonator are integrally molded by molding resin. Extending radiating leads are provided for an island of a lead frame, in which the IC chip is disposed, and a portion of the radiating leads is exposed out of the molding resin so that the heat generated in the IC chip is positively radiated. Radiating leads are also attached to the case of the resonator to project out of the molding resin so that heat conducted to the case is radiated to minimize influence of heat upon the piezoelectric element. In an oscillator, the size of which has been reduced and the frequency of which has been raised, heat generated in the IC chip is radiated to the outside of the molding resin so that a rise in the temperature of the oscillator is minimized. Thus, an oscillator can be realized which exhibits excellent accuracy and reliability for a long time and which is adaptable to high frequencies.

The invention provides a piezoelectric oscillator including a semiconductor integrated circuit and a piezoelectric resonator or a voltage-controlled oscillator including a semiconductor integrated circuit, a piezoelectric resonator and another electronic component. The piezoelectric resonator has a cross-sectional shape of an ellipse or a track. The semiconductor integrated circuit and the electronic component are molded with a resin into a very thin unit.

A lead frame has a pair of side frames each having a plurality of positioning holes and spaced apart from each other in a width direction of the lead frame. At least one section bar extends between the pair of side frames. First lead sections extend from the section bar and are arranged at predetermined intervals along the width direction of the lead frame. Second lead sections extend from the section bar along the width direction of the lead frame and are disposed in confronting and spaced-apart relation to the respective first lead sections in a longitudinal direction of the lead frame to define a frame area extending between the pair of side frames. Each of the second lead sections has a pair of separate and independent protruding portions disposed adjacent one another.

A voltage-controlled oscillator is provided having a semiconductor integrated circuit and a piezoelectric resonator. A variable-capacitance diode may be connected in series with the piezoelectric resonator. The variable-capacitance diode may be further mounted a land of a lead frame. The piezoelectric resonator, variable-capacitance diode and lead frame may be resin molded into a single unit. In operation, a signal may be applied to a node located between the variable-capacitance diode and the DC-cutting capacitor.