| 摘要 |
A coupling circuit (1) for use between a modulator or mixer (2) and a ceramic filter (3) in amplitude modulation receivers, of a type intended for connection to the output of the modulator (2) which would include an output stage (4) consisting of a pair of differential cells (7, 8) connected in parallel to each other, comprises an impedance transformer (9) having its primary winding (10) terminals respectively connected to the terminals (6a, 6b) of the differential cell pair and the midpoint (11) of the winding (10) connected to a supply pole (VS). The secondary winding (12) of said transformer is connected between ground and the ceramic filter (3), and the resulting coupling circuit (1) affords improved value, in terms of decibels, of the receiver cross modulation and of the ratio, also in terms of decibels, of rejection at an intermediate frequency IF. <IMAGE>
|
