Tuning voltage generating apparatus of voltage synthesizer type

A tuning voltage generating apparatus of a voltage synthesizer type for supplying a tuning voltage to a tuner employing a variable reactance element as a tuning element, comprising:

• input pulse signal providing means for providing an input pulse signal having information encoded therein corresponding to a frequency to be received,
• first reference voltage generating means including a voltage dividing means for generating a first reference voltage having a first level by dividing an output of a constant voltage source by said voltage dividing means,
• voltage converting means responsive to said input pulse signal and said first reference voltage for voltage converting said input pulse signal into an output pulse signal using said first reference voltage,
• low-pass filter means for converting the voltage converted pulse signal from said voltage converting means into a direct current tuning voltage for application to said tuner,
• an upper limit of said tuning voltage being determined by said voltage dividing means, and
• lower limit determing means comprising a reference voltage generating circuit for determining a lower limit of the tuning voltage from said low-pass filter means.

A tuning voltage generating apparatus of a voltage synthesizer type for supplying a tuning voltage to a tuner employing a variable reactance element as a tuning element, comprising:

• input pulse signal providing means for providing an input pulse signal having a pulse width corresponding to a frequency to be received,
• reference voltage generating means for generating first and second reference voltages having at least two different levels,
• voltage converting means responsive to said input pulse signal and a reference voltage from said reference voltage generating means for voltage converting said input pulse signal to an output pulse signal,
• low-pass filter means for converting the output pulse signal from said voltage converting means into a direct current tuning voltage for application to said tuner,
• an upper limit of said tuning voltage being determined by at least one of said first and second reference voltages from said reference voltage generating means, and
• means for providing only the relatively lower level reference voltage of said first and second reference voltages to said voltage converting means.