| 摘要 |
PCT No. PCT/FI90/00099 Sec. 371 Date Oct. 24, 1991 Sec. 102(e) Date Oct. 24, 1991 PCT Filed Apr. 10, 1990 PCT Pub. No. WO90/13173 PCT Pub. Date Nov. 1, 1990.The invention relates to a high-frequency amplifier of a radio transmitter, comprising an amplifier stage the gain of which can be automatically controlled by a gain control feedback (L15, L16, D10, D11, A1, A2) coupled from a subsequent amplifier stage or the out-put of the high-frequency amplifier. The power consumption of the gain control is reduced, and the frequency stability of the amplifier stages and the preceding voltage-controlled oscillator is improved by the high-frequency amplifier according to the invention, wherein the amplifier stage comprises a two-gate field-effect transistor (Q1), the first gate (G1) of which constitutes the signal input, and the second gate (G2) of which constitutes the gain control input, to which said feedback (L15, L16, D10, D11, A1, A2) is coupled, and wherein the operating point of the transistor (Q1) is set by biasing the first gate (G1).
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