Patents Represented by Attorney Lockwood Burton
  • Patent number: 4159489
    Abstract: A magnetic record reproducing system preamplifier includes an inductive choke in the emitter circuit of a first stage transistor amplifier whereby to provide a frequency responsive variable input impedance whereby to maintain a proper impedance relationship between the inductive transducer and the input impedance of the first stage amplifier. A second stage transistor amplifier is connected to the output of the first stage amplifier in cascode relationship, reducing the effective voltage gain of the first stage to substantially zero. The choke in the input circuit of the first stage amplifier acts as a degenerative feedback at higher frequencies, effectively reducing the bias current through the first stage transistor. The base emitter capacitance of the first stage transistor tends to resonate with the inductance of the transducer. The effective degenerative feedback at that first stage transistor tends to push that resonant frequency beyond the desired or useful frequency band of the system.
    Type: Grant
    Filed: September 30, 1976
    Date of Patent: June 26, 1979
    Assignee: Honeywell Inc.
    Inventor: Michael F. Braitberg