Linear Vco

This voltage-controlled oscillator (VCO) utilizes an LF356 operational amplifier to create a linear relationship between frequency and voltage, employing the CMOS HC4046. The frequency range can be adjusted by modifying the capacitor connected between pins 6 and 7 of the HC4046. The linearization depicted in the schematic is accomplished by using the internal transistor of the HC4046 instead of an external component.

The voltage-controlled oscillator (VCO) circuit described leverages the LF356 operational amplifier to establish a linear frequency-to-voltage characteristic, which is critical for applications requiring precise frequency modulation. The CMOS HC4046 phase-locked loop (PLL) integrated circuit serves as the core of this design, providing robust frequency synthesis capabilities.

In this configuration, the operational amplifier is configured to amplify the control voltage applied to its input. The output frequency of the VCO is directly proportional to this control voltage, allowing for smooth and predictable frequency adjustments. The frequency range is determined by the capacitor connected between pins 6 and 7 of the HC4046. By selecting different capacitor values, the user can tailor the operational frequency range of the VCO to meet specific application requirements.

Moreover, the use of the HC4046's internal transistor for linearization simplifies the circuit design by reducing the need for external components. This approach not only minimizes the component count, thereby enhancing reliability, but also helps in maintaining a compact design footprint. The internal transistor aids in achieving a more stable and linear response, which is essential for applications where frequency accuracy is paramount.

In summary, this VCO design offers an efficient and effective solution for generating a linear frequency response with adjustable ranges, making it suitable for various electronic applications, including signal processing, communication systems, and frequency modulation tasks. The integration of the LF356 op amp with the HC4046 PLL ensures a high-performance oscillator capable of meeting demanding specifications. This VCO uses an LF356 op amp to produce a linear frequency vs. voltage characteristic using the CMOS HC4046. The frequency rang e can be changed by changing the capacitor connected between pins 6 and 7 of the HC4046. Using the HC4046"s internal transistor instead of an external component achieves the linearization in diagram.