| 摘要 |
PURPOSE:To utilize harmonic waves by using a Lamb wave delay line oscillator having three reed screen transducers and two FETs as a variable resistance means so as to improve the frequency characteristic and the modulation sensitivity. CONSTITUTION:When an electrical signal from an amplifier circuit 20 is impressed to an input electrode 14, the electrical signal is converted into a Lamb wave, propagated into a piezoelectric substrate 11, reaches an output electrode 15, where the wave is converted into an electrical signal and inputted to an amplifier circuit 20. The amplifier circuit 20 compensates the insertion loss component by a Lamb wave device 10 and outputs a signal. The Lamb wave device 10 and the amplifier 20 constitute a feedback loop oscillator. The two FETs 16, 17 are provided between a modulation electrode 13 and a modulation electrode 12 placed just therebehind in this state, a resistance value between the drain and source of the FET is changed, then the terminating condition is changed accordingly and the oscillating frequency is changed. The frequency shift is obtained via an output terminal 40. This is handled equivalently as the arrangement of a phase shifter depending on the terminal condition on the Lamb wave device 10. |
