Patent ID: 6225873
Filing Date: 2001-05-01
Classification: H03B,H03C

Abstract:
A frequency modulated circuit for selectably oscillating at a first or a second oscillating frequency, the circuit comprising:a balanced oscillator comprising:a resonator for generating a reference signal;an amplifier for amplifying said reference signal; anda resonating circuit for generating an oscillating output in response to said amplifier amplifying said reference signal; anda frequency shift key modulator for providing a first or a second impedance responsive to a select signal having a voltage, the value of each of said impedances being fixed independently of the select signal voltage, said oscillating output oscillating at the first oscillating frequency if said modulator comprises said first impedance and oscillating at the second oscillating frequency if said modulator comprises said second impedance, said modulator comprising:a transistor circuit driven into a saturation mode if said select signal is at a first voltage and driven into an off mode if said select signal is at a second voltage; anda filter for removing unwanted reflections generated when said transistor circuit is in an active mode.