Abstract:
PROBLEM TO BE SOLVED: To provide a piezoelectric oscillation circuit and a constant temperature piezoelectric oscillator that can stabilize an oscillation frequency by suppressing variations in interterminal potential of a vibrator even when a fixed potential varies.SOLUTION: The piezoelectric oscillation circuit includes: a Colpitts oscillator circuit 30; a first circuit section 20 comprising a circuit including a variable capacity capacitor for controlling an oscillation frequency; a second circuit section 50 comprising a circuit including a resistor; and a piezoelectric vibrator 40 having a first terminal 41 connected to the first circuit section and the second circuit section and a second terminal 42 connected to the Colpitts oscillator circuit. The Colpitts oscillator circuit 30 connects the second terminal 42 to a fixed potential via a dividing resistor, and the second circuit section 50 connects the first terminal 41 to the fixed potential via the resistor.
Abstract:
PROBLEM TO BE SOLVED: To obtain a circuit configuration for compensation of leakage currents in a voltage-controlled oscillator of a PLL circuit. SOLUTION: A control voltage applied to the oscillator by way of a loop filter (20)is generated by a phase detector (16) as a function of the phase difference between the phase of a reference signal and the phase of the signal outputted by a voltage-controlled oscillator (12). The oscillator (12) contains varicap diodes (28, 30) to which the control voltage is applied via a control line (34). A compensation circuit (K) provided with varicap diodes (36, 38) in the same configuration reproduces, at one of its outputs (44), the control voltage, applies it to the varicap diodes (36, 38) in the compensation circuit (K), supplies, from its other output (46), a current equal to the leakage current of the varicap diodes (36, 38). A current shunt-off branch leads from the control line (34), by way of which a current which corresponds to the current supplied by the operational amplifier (40) flows from the control line (34). COPYRIGHT: (C)2009,JPO&INPIT