Abstract: A video intermediate-frequency signal processing device capable of receiving FM broadcasts, includes a first FM detecting unit for demodulating an intermediate-frequency signal from a sound intermediate-frequency detecting unit using a phase-locked loop, and for furnishing a demodulated FM signal, a second FM detecting unit for detecting or demodulating a reference signal applied to generate a reference DC voltage, a comparator for obtaining a difference between the modulated FM signal from the first FM detecting unit and the reference DC voltage from the second FM detecting unit, and for furnishing, as a sound signal, a signal having a value corresponding to the difference, and a feedback unit for, when receiving FM broadcasts, filtering the output of the comparator, and feeding the filtered output back to a low-pass filter of a phase-locked loop included in a video detecting unit.

Abstract: A digital-to-analog converter includes a ladder circuit and transistors. A control voltage generating circuit is coupled to the transistors in a feedback configuration to control current flowing through the transistors. The control voltage generating circuit includes an operational amplifier coupled to a transistor. Using the control voltage generating circuit, the digital-to-analog converter of the present invention produces an analog output voltage resistant to variation in the DC forward current gain of the transistors.