To adjust temperature compensation sensitivity and control sensitivity with high precision by combining a series reference resistor and a parallel variable resistor in an inverted L shape and configuring the parallel variable resistor with a high resistance part for rough adjustment and a low resistance part for fine-adjustment.

A 1st TCO circuit network 21 is made up of a 1st series reference resistor 23 and a 1st parallel variable resistor circuit network 24, and a 2nd TCO circuit network 22 is made up of a 2nd series reference resistor 25 and a 2nd parallel variable resistor circuit network 26. Each one terminal of the 1st and 2nd series reference resistors 23,25 is connected to a changeover circuit 11 to apply a voltage to variable capacitance diodes 27, 28 of a variable capacitance diode section T via TCO circuit networks 21, 22. As means of dividing the voltage applied to the variable capacitance diode section 7, each series reference resistor and each parallel variable resistor are combined in an inverted-L shape, the parallel variable resistor is made up of a high resistance part for rough adjustment and a low resistance part for fine-adjustment and each series reference resistor and each high resistor part are manufactured by the same process.