| 摘要 |
<p>Tuneable resonance amplifier comprising a cascade circuit of first and second sections each having a controllable gain and comprising first and second transconductance amplifiers, respectively, outputs of which are coupled via first and second capacitors to inputs of the second and first gain controlled amplifiers, said first and second capacitors being coupled in parallel to first and second load resistors to form therewith first and second parallel RC filters, respectively, a tuning control current being supplied to control inputs of the first and second transconductance amplifiers, said first transconductance amplifier having a differential pair of first and second output terminals and said second transconductance amplifier having a differential pair of third and fourth output terminals. To provide a highly selective tuneable resonance amplifier operable in a wide tuning range at a low supply voltage, said first load resistor is coupled between the first and second output terminals, and said second load resistor being coupled between the third and fourth output terminals respectively, said first to fourth output terminals being respectively coupled to first to fourth DC current paths shunting at least a substantial part of said tuning control current to a supply voltage. <IMAGE></p> |
