A phase-locked loop apparatus (PLL apparatus) and a tuning voltage providing circuit thereof are provided. The PLL apparatus is for receiving an input signal and producing an output signal according to the received input signal. The PLL apparatus includes a voltage-controlled oscillator (VCO), a loop filter and a tuning voltage providing circuit. The VCO receives a control voltage and produces the output signal according to the received control voltage. The loop filter has a resistor-capacitor network and the network receives the control voltage and is coupled to a reference voltage. The tuning voltage providing circuit receives the output signal and the input signal and provides a tuning voltage to the resistor-capacitor network according to the input signal and the output signal.