Abstract: A microwave oscillator in a loop configuration comprises three substantially identical amplifier stages each having its own phase shift at a selected oscillating frequency. A transmission delay element having a phase shift at the selected oscillating frequency, is also in the loop configuration, so that the oscillator has zero phase shift around the loop at the oscillating frequency. Each amplifier stage has at least one active component with resistive feedback, which is connected to DC blocking and filtering capacitors. Capacitor values between 2.2 and 5.1 pf are used making the oscillator design amenable to cost effective conventional hybrid and semiconductor processes.

Abstract: A voltage controlled oscillator is tuned with a network comprising two varactor diodes and two transmission lines. By selecting appropriate values of varactor capacitance and transmission line length and width the overall reactance of the network is such that, when a varactor tuning voltage is varied, the output frequency of the voltage controlled oscillator will vary in an fashion with respect to the tuning voltage. Such a voltage controlled oscillator is gain compensated and exhibits a controlled modulation sensitivity over a range of frequencies. If the required frequency range of the oscillator is known beforehand, an alternate embodiment of the invention may be employed in which one of the varactor diodes is replaced with a fixed capacitor having a suitable value for the desired frequency range.

Abstract: A circuit which modulates an r.f. carrier to produce an FM signal having a substantially linear frequency relation to an applied modulating voltage over a selected deviation bandwidth. An r.f. oscillator having an output matching circuit supplies the carrier to a modulator. The impedance of the oscillator is adjusted by the matching circuit to present a desired reactive mismatch to the modulator over the bandwidth. The modulator includes a pair of voltage dependent reactive impedance elements, oppositely biased and separated by a quarter wavelength line which acts as an impedance inverter. A modulating voltage applied to both of the elements causes a reactive imbalance therebetween, affecting either a net inductive or capacitive change in the load impedance presented to the oscillator. The center frequency of the circuit reacts in a substantially linear manner to the modulating voltage over the deviation bandwidth.