oscillator for the generation of bersvengningspulser in forhallande to a synkroniseringssvengning coherent phase of bersvengningen

摘要

1328327 Transistor oscillator circuits; keying circuits; pulse radar SIEMENS-ALBIS AG 9 Aug 1972 [10 Sept 1971] 37135/72 Headings H3R H3T and H4D An oscillator circuit providing phase-control of oscillations relative to a synchronizing oscillation, comprises a first amplifier stage 1 in the form of an emitter-follower whose output is connected to the imput of a second amplifier stage 2 in the form of a common-base stage, the output of which is connected to the input of the first amplifier via a frequency-selective positive feedback path 6. The output of the first amplifier stage 1 is connected to the input of the second amplifier stage 2 via a transient-free switching and amplitude-limiting stage 3 keyed by a control voltage, while the input of the second amplifier stage 2 is connected via an isolating resistor 21 to an input terminal UT for the synchronizing oscillation. In the embodiment, the switching and amplitude-limiting stage 3 comprises series-connected and reversely poled diodes 33, 35, together with a differential amplifier comprising transistors 47, 48 having the emitter-collector path of a further transistor 49 as common emitter impedance. Normally, transistor 47 is cut off and transistor 48, so that diodes 33, 35 which are biased from the collector circuits of these transistors via impedances 37, 39 which may be resistors or inductors, and terminal 34, are conductive. A positive-going pulse (US, Fig. 3, not shown) on terminal US biases transistor 47 conductive, so that transistor 48 becomes non-conductive, and the diodes 37, 39 become non-conductive, breaking the feedback path of the oscillator. The impedances 37, 39 may comprise the collector to emitter paths of a pair of transistors, provided with suitable base bias and with their emitters connected together and to the collector of transistor 47 (Fig. 2, not shown). The arrangement may be used in pulseoperated Doppler radar devices in which the phase of the echo pulses must be compared with that of the original transmitted pulse oscillations, and it is necessary for phase information regarding the transmitted signal to be stored until the time of the echo reception.