| 摘要 |
<p>1481387 Transistor amplifiers BENDIX CORP 21 Nov 1975 [31 Jan 1975] 48036/75 Heading H3T A power amplifier, e.g. for 1090 MHz, in which high output is obtained by using parallel amplifying channels, comprises a plurality of amplifying elements 100-103, input means 54 for distributing input signal power between the elements and including a plurality of transmission lines 58-64 having different lengths and therefore unequal phase delays and being interconnected by resistors 70-75 at points having the same phase under normal operating conditions, and in like manner output means including transmission lines 80-86, resistors 90- 95, and means 76 for phase coherent addition of the amplified outputs. Under normal conditions the signal is equally distributed between the elements, and only negligible currents flow in the resistors 70-75, 90-95, but if the signal is unequally distributed, e.g. due to load mismatching or during preliminary setting-up, the points interconnected by resistors no longer have the same phase, and dissipative currents flow tending to protect the amplifying elements from overload, this action being dependent on the lines 58-64, 80-86 not having equal lengths. Input line 64 is coupled by a capacitor 106 to an impedance transformer 110 which matches line 64 to the emitter of transistor 112 which is a grounded base amplifier. The impedance transformer includes a tuning capacitor 120 and a resistor 122 both coupling to earth 118. Similarly an output impedance transformer 114 has a tuning capacitor 124, a resistor 126 and an output coupling capacitor 108. Unequal distribution of the signal between the amplifying transistors is associated with inequality of the mean emitter-collector capacitances owing to the non-linear relation between junction capacitance and emitter-collector voltage, Figs. 3-6 (not shown).</p> |
