Wave transmission lines and networks – Plural channel systems – Having branched circuits
Patent
1992-11-30
1994-04-26
Gensler, Paul
Wave transmission lines and networks
Plural channel systems
Having branched circuits
333103, 333109, H01P 110, H01P 115
Patent
active
053070321
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Field of the Invention
The present invention relates to a signal selector and, more particularly, to a signal selector using a distributed coupled line obtained by electromagnetic coupling to be able to perform selective transmission with a small signal distortion in a wideband ranging from a low frequency wave to a high-frequency wave.
2. Description of the Related Art
As a conventional signal switch used in a wideband ranging from a DC band to a microwave band, a mechanical switch has been mainly used. However, as in a case wherein a circuit is switched in accordance with sweeping, a large number of continuous switching operations pose a problem on the service life of a switching contact. In addition, although a switch using a semi-conductor element is known, a capacitor for isolating a signal line from a control bias line must be inserted in series in the signal line, and a switching operation from a low-frequency band (band close to a DC having about 100 Hz) to a microwave band is difficult.
On the other hand, in a wideband spectrum analyzer, a switch arranged by incorporating a diode in a YTF (variable tuning filter using a YIG resonator) disclosed in U.S. Pat. No. 4,450,422 is used, thereby realizing wideband sweeping including a switching operation. However, since this switch has an arrangement requiring a tuning operation, it is difficult to apply this switch to equipment in other fields, such as a signal generator.
The arrangement of a conventional signal selector in which a capacitor and a diode are inserted in a signal line is shown in FIG. 21, and the equivalent circuit of the signal selector is shown in FIG. 22. The prior art will be described below with reference to FIGS. 21 and 22.
An AC input signal is supplied to a terminal A, and is supplied to the anodes of diodes D1 and D3 through a DC blocking capacitor C1. When the AC input signal is to be switched to a terminal B side, a negative bias voltage is applied to a terminal D, and a positive bias voltage is applied to a terminal E. In this manner, the diode D1 is forward-biased to be turned on, and a diode D2 is reverse-biased to be turned off. As a result, a closed path is formed between the terminals A and B, and the AC input signal is supplied to the terminal B. On the other hand, the diode D3 is reverse-biased to be turned off. In addition, a diode D4 is forward-biased to be turned on. As a result, the terminal A is disconnected from a terminal C, and the input signal is not supplied to the terminal C.
Since the diodes D1 to D4 serve as switches, they can be expressed in an AC form by an equivalent circuit shown in FIG. 22. That is, the diodes D1, D2, D3, and D4 correspond to switches S1, S2, S3, and S4, respectively.
On the other hand, when the AC input signal is to be switched to the terminal C side, in contrast to the above description, a positive bias voltage is applied to the terminal D, and a negative bias voltage is applied to the terminal E. In this manner, the diode D3 is forward-biased to be turned on, and the diode D4 is reverse-biased to be turned off. As a result, a closed path is formed between the terminals A and C, and the AC input signal is supplied to the terminal C. On the other hand, the diode D1 is reverse-biased to be turned off. The diode D2 is forward-biased to be turned on. As a result, the terminal A is disconnected from the terminal B, and the AC input signal is not supplied to the terminal B.
In the equivalent circuit used in this case, in contrast to the states of the switches shown in FIG. 22, the switches S1 and S4 are set in an open state, and the switches S3 and S2 are set in an ON state.
Note that the capacitor C1 and capacitors C2 and C3 in FIG. 21 are arranged to block a DC bias voltage so as to prevent loads or signal sources connected to the terminals A, B, and C from the influence of the DC bias voltage for ON/OFF-controlling the diodes. Resistors R1 to R3 are arranged to assure a path for a DC bias current, to keep a high impedance between a path through which the signal passes and
REFERENCES:
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patent: 4004257 (1977-01-01), Geissler
patent: 4450422 (1984-05-01), Lockwood
patent: 4985689 (1991-01-01), Kadowaki et al.
IBM Technical Disclosure Bulletin; H. R. Foglia "Transmission Line Transformer Load Sharing Switch"; vol. 7, No. 6, Nov., 1964; p. 466.
Soviet Inventions Illustrated; Derwent Publicaions Ltd., London, G.B., Class WO2, AN 86-278018/42 & SU-A-1220031 (Petrenko) Mar. 23, 1986. Abstract.
"An X-Band 12W GaAs Monolithic Transmit-Receive Switch", M. Matsunaga et al, The Transactions of the IEICE, vol. E70, No. 4, Apr. 1987, pp. 259-260.
Anritsu Corporation
Gensler Paul
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