Electric wave filters utilizing piezoelectric resonators

Claim 2

IN AN AMPLIFIER STAGE HAVING AN INPUT, AN OUTPUT AND A COMMON TERMINAL THE COMBINATION COMPRISING: A TRANSISTOR DEFINING A LOW INPUT IMPEDANCE AND HAVING AN INPUT ELECTRODE, AN OUTPUT ELECTRODE AND A COMMON ELECTRODE; CIRCUIT MEANS COUPLING THE INPUT TERMINAL OF THE AMPLIFIER STAGE TO SAID INPUT ELECTRODE OF SAID TRANSISTOR; CIRCUIT MEANS COUPING SAID OUTPUT ELECTRODE OF SAID TRANSISTOR TO THE OUTPUT TERMINAL OF THE AMPLIFIER STAGE; A FREQUENCY SENSITIVE PARALLEL CIRCUIT CONSISTING OF TWO CIRCUIT BRANCHES COUPLED BETWEEN SAID COMMON ELECTRODE OF SAID TRANSISTOR AND THE COMMON TERMINAL OF THE AMPLIFIER STAGE; AN ELECTRICAL RESISTANCE CONNECTED IN ONE OF SAID CIRCUIT BRANCHES; AND AN ELECTROMECHANICAL RESONATOR OF FERROELECTRIC CERAMIC MATERIAL CONNECTED IN THE OTHER OF SAID CIRCUIT BRANCHES, SAID RESONATOR BEING SERIES RESONANT AT A PERDETERMINED SIGNAL FREQUENCY TO EFFECTIVELY SHORT CIRCUIT SAID RESISTANCE TO MINIMIZE NEGATIVE FEEDBACK IN SAID AMPLIFIER STAGE AND THE INPUT IMPEDANCE OF SAID AMPLIFIER STAGE AT SIGNAL REQUENCIES IN THE IMMEDIATE VICINITY OF SAID PREDETERMINED FREQUENCY.

Claim 3

A BAND-PASS FILTER COMPRISING: A CASCADE OF TRANSISTOR AMPLIFICATION STAGES EACH OF WHICH HAS AN INPUT AND OUTPUT AND COMPRISES A LOW IMPEDANCE JUNCTION TRANSISTOR HAVING BASE, EMMITTER AND COLLECTOR ELECTRODES THE POWER TRANSFER BETWEEN ADJACENT STAGES BEING MAXIMUM WHEN THE INPUT IMPEDANCE OF A STAGE MATCHES THE OUTPUT IMPEDANCE OF A PRECEDING STAGE; CIRCUIT MEANS CONNECTING THE TRANSISTOR IN AT LEAST ONE INTERMEDIATE STAGE WITH ITS EMITTER COMMON TO THE INPUT AND OUTPUT OF SAID ONE STAGE; A FREQUENCY SENSITIVE CIRCUIT CONSISTING OF TWO PARALLEL CIRCUIT BRANCHES CONNECTED IN SERIES WITH SAID EMITTER OF SAID ONE STAGE; AN ELECTRICAL RESISTANCE CONNECTED IN ONE OF SAID CIRUCIT BRANCHES; AND AN ELECTROMECHANICAL RESONATOR OF FERROELECTRIC CERAMIC MATERIAL CONNECTED IN THE OTHER SAID CIRCUIT BRANCHES, SAID RESONATOR BEING RESONANT AT A PREDETERMINED SIGNAL FREQUENCY TO EFFECTIVELY SHORT CIRUCIT SAID RESISTANCE TO MINIMIZE THE INPUT IMPEDANCE OF SAID ONE STAGE AT SIGNAL FREQUENCIES IN THE IMMEDIATE VICINITY OF SAID PREDETERMINED FREQUENCY, THE INPUT IMPEDANCE OF SAID ONE STAGE BEING STUBSTANTIALLY MATCHED WITH THE OUTPUT IMPEDANCE OF A PRECEDING STAGE AT SIGNAL FREQUENCIES IN THE IMMEDIATE VICINITY OF SAID PREDETERMINED FREQUENCY.

Claim 4

A BAND-PASS FILTER COMPRISING: A CASCADE OF TRANSISTOR AMPLIFICATION STAGES EACH OF WHICH HAS AN INPUT AND OUTPUT AND COMPRISES A LOW IMPEDANCE JUNCTION TRANSISTOR HAVING BASE, EMMITTER AND COLLECTOR ELECTRODES THE POWER TRANSFER BETWEEN ADJACENT STAGES BEING MAXIMUM WHEN THE INPUT IMPEDANCE OF A STAGE MATCHES THE OUTPUT IMPEDANCE OF A PRECEDING STAGE; CIRCUIT MEANS CONNECTING THE TRANSISTOR IN AT LEAST ONE INTERMEDIATE STAGE WITH ITS EMITTER COMMON TO THE INPUT AND OUTPUT OF SAID ONE STAGE; A FREQUENCY SENSITIVE CIRCUIT CONSISTING OF TWO PARALLEL CIRCUIT BRANCHES CONNECTED IN SERIES WITH SAID EMITTER OF SAID ONE STAGE; AN ELECTRICAL RESISTANCE CONNECTED IN ONE OF SAID CIRUCIT BRANCHES; AND AN ELECTROMECHANICAL RESONATOR OF FERROELECTRIC CERAMIC MATERIAL CONNECTED IN THE OTHER SAID CIRCUIT BRANCHES, SAID RESONATOR BEING RESONANT AT A PREDETERMINED SIGNAL FREQUENCY TO EFFECTIVELY SHORT CIRUCIT SAID RESISTANCE TO MINIMIZE THE INPUT IMPEDANCE OF SAID ONE STAGE AT SIGNAL FREQUENCIES IN THE IMMEDIATE VICINITY OF SAID PREDETERMINED FREQUENCY, THE INPUT IMPEDANCE OF SAID ONE STAGE BEING STUBSTANTIALLY MATCHED WITH THE OUTPUT IMPEDANCE OF A PRECEDING STAGE AT SIGNAL FREQUENCIES IN THE IMMEDIATE VICINITY OF SAID PREDETERMINED FREQUENCY.