Patent ID: 6239664
Filing Date: 2001-05-29
Classification: H03B

Abstract:
An oscillator circuit having an input port and an output port and capable of receiving a frequency tuning signal on said input port and generating a tunable high-frequency output signal on said output port, said oscillator circuit comprising:a tuning element coupled to said input port and having a variable capacitance responsive to said frequency tuning signal;a first inductor having a first terminal coupled to said tuning element and a second terminal;a SAW resonator having a first terminal coupled to said second terminal of said first inductor and a second terminal;a second inductor having a first terminal coupled to said first terminal of said SAW resonator and a second terminal coupled to said second terminal of said SAW resonator; anda negative resistance generating circuit coupled to said second terminal of said SAW resonator, wherein, at a first oscillation frequency of said oscillator circuit, a reactance looking into said input port is approximately zero and a resistance looking into said input port is negative, wherein said negative resistance generating circuit comprises a transistor having a base coupled to said second terminal of said SAW resonator a third inductor having a first terminal coupled to an emitter of said transistor and a second terminal coupled to ground, and a first capacitor and a second capacitor coupled in series between said base of said terminal and ground.