| 摘要 |
<p>1,242,859. Transistor amplifying circuits. RCA CORPORATION. 11 Dec., 1968 [11 Dec., 1967], No. 58806/68. Heading H3T. An amplifying circuit comprises a field effect transistor with a first gate electrode 16 for connection to a source of input signals and a second gate electrode 18 for connection to a gain controlling potential, impedance means, i.e. resistor 40, connected to the source electrode and in series with the source to drain path and a biasing arrangement interconnecting the first and second gate electrodes which causes the potential of the first gate electrode relative to the potential of the source electrode to change in a polarity direction opposite to a change in potential of the second gate electrode relative to the potential of the source electrode. As shown, the first gate electrode derives a fixed bias from potentiometer 32, 34 and a variable bias from that applied to the second gate electrode via resistor 30. A resistor 52 which may be omitted (Fig. 2, not shown) applies a fixed bias to the second gate electrode. The arrangement is intended to bias the first gate electrode so as to minimize cross-modulation as the gain control bias is varied.</p> |
