| 摘要 |
1485145 Diode switching circuits SIEMENS AG 2 Sept 1974 [12 Sept 1973] 38228/74 Headings H3T and H3P In a multichannel r.f. switching circuit, each channel comprises one conductor at a reference potential and line conductor, a series diode and a shunt diode on the input side of the series diode and a drive circuit effective in response to said reference potential on its input to block the series diode and render the shunt diode conductive to form an effective termination of the channel. As described the circuit comprises a plurality of gates as shown in Fig. 2 each having a separate input I and common output O. Transistor T2 is normally blocked and T3 normally conductive so that + 5 v. is applied to the anode of D21 and D11 is reversed biased to block the signal path from I to O. To unblock the path, the base of transistor T1 is earthed, turning on transistors T1 and T2 and cutting off transistor T3. This reversed the bias conditions on diodes D11 and D21. The diodes D11 of the plurality of gates may be arranged in a star pattern around a common point on a printed circuit board having a ground plane on the other side, Fig. 3 (not shown). The remainder of the circuits are mounted on individual thickfilm circuit boards parallel to the main board and surrounding the diodes D11. The connections are arranged to equalize path-lengths and impedances. |
