# US 4,379,996 A · Enhancement of class C operation of bipolar junction transistor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,379,996 A - Document ID: US4379996A - Status: Granted - Kind: A - Application number: 06/234,132 - Filed: 1981-02-13 - Granted: 1983-04-12 - Earliest claimed: 1981-02-13 - Assignees: Rockwell International Corporation - Inventors: Robert J. Weber - Web page: https://patentgrep.com/patent/US4379996A ## CPC - H03F 3/21: with semiconductor devices only {(H03F3/245 takes precedence)} - H03F 3/19: with semiconductor devices only - H03F: AMPLIFIERS ## Abstract Pulsed RF operation of a class C biased BJT is enhanced using a three element system to control the BJT emitter current. The three element system includes a transformer having a secondary connected in the emitter current path. Connected to the transformer primary are the other two elements, namely, an impedance and a pulse source. The three elements cooperate to cause the emitter current to substantially conform to a desired or predetermined pulse waveform. ## Claims ### Claim 1 A circuit comprising a class C biased BJT which is for outputting RF bursts, and means for controlling the shape of the envelope of said RF burst, said shape controlling means comprising: first means comprising a transformer having a primary winding with M.sub.p turns and a secondary winding with M.sub.S turns where M.sub.p :M.sub.S >1, said secondary winding being connected in the BJT emitter current path, pulse source second means, connected to the primary winding, for providing pulses having predetermined parameters, impedance third means connected to the primary winding, said first, second, and third means cooperating to control the BJT emitter current and cause the BJT emitter current envelope to substantially conform to a predetermined function of time I.sub.e (t), where I.sub.e (t) is a pulse waveform. ### Claim 2 (depends on 1) Apparatus as defined in claim 1 wherein the polarity of the second means pulses, and the phase of the secondary winding, are appropriate to aid, rather than oppose, emitter current flow. ### Claim 3 (depends on 2) Apparatus as defined in claim 2 wherein the second means pulses are substantially rectangular in shape. ### Claim 4 (depends on 3) Apparatus as defined in claim 3 wherein the impedance third means has substantially no reactance component. ### Claim 5 (depends on 1, 2) Apparatus as defined in claims 1, 2, or 3 wherein the impedance third means has substantially no reactance component and has substantially no resistance component. ### Claim 6 (depends on 1, 2, 3) Apparatus as defined in claims 1, 2, 3, or 4 wherein said impedance third means includes a temperature variable resistance for reducing emitter current dependency on temperature. ### Claim 7 (depends on 1, 2) Apparatus as defined in claims 1 or 2 wherein (i) said third means comprises a capacitor and (ii) said second means pulses are substantially rectangular in shape. ### Claim 8 (depends on 1, 2) Apparatus as defined in claims 1 or 2 wherein (i) said third means comprises a capacitor and (ii) said second means pulses are substantially pseudo-Gaussian in shape. ### Claim 9 (depends on 1, 2) Apparatus as defined in claim 1, 2, or 3 wherein the pulse waveform I.sub.e (t) is substantially rectangular in shape. ### Claim 10 (depends on 1, 2) Apparatus as defined in claims 1, 2, or 3 wherein the pulse waveform I.sub.e (t) is substantially pseudo-Gaussian in shape. ### Claim 11 Apparatus comprising: a class C biased BJT for outputting RF bursts, a transformer having (i) a primary winding with a first number of turns and (ii) a secondary winding with a second number of turns, said first number being greater than said second number, and said secondary winding being connected in the BJT emitter current path, means for providing pulses having predetermined parameters, and being connected to said primary winding for delivering pulses thereto, whereby, said pulses cause the BJT emitter current envelope to substantially conform to a predetermined function of time where said predetermined function of time is a pulse waveform. ### Claim 12 (depends on 11) Apparatus as defined in claim 11 wherein said pulse providing means includes a resistance means for having a predetermined effect on the pulse parameters. ### Claim 13 (depends on 12) Apparatus as defined in claim 12 wherein said resistance means includes a temperature variable resistance for reducing emitter current dependency on temperature. ### Claim 14 (depends on 11) Apparatus as defined in claim 11 wherein said pulse providing means includes a capacitance means for having a predetermined effect on said pulse parameters. ### Claim 15 (depends on 11, 12, 13) Apparatus as defined in claims 11, 12, 13, or 14 wherein the pulse providing means pulses have a shape which is a predetermined one of substantially rectangular or substantially pseudo-Gaussian.