Multi-ceramic layer switch circuit

• US 5,513,382 A
• Filed: 03/20/1995
• Issued: 04/30/1996
• Est. Priority Date: 03/31/1993
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Agahi-Kesheh, Darioush, Huang, Rong-Fong, Kommrusch, Richard S.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): LE, THANH C
• Application Number:
  US08/407,787
• Time in Patent Office: 407 Days
• Field of Search: 455/78, 455/80, 455/82, 455/83, 455/84, 333/103, 333/104, 333/262, 333/246, 333/204, 333/202
• US Class Current: 455/83
• CPC Class Codes: H04B 1/48 in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter H04B1/46 takes precedence

Abstract

A switch circuit for a cellular radiotelephone operable in a TDMA communication scheme. The switch circuit is disposed upon a plurality of tandemly-positioned ceramic substrates having transmission lines disposed upon one of the ceramic substrates. The switch circuit alternately connects transmitter circuitry to an antenna or receiver circuitry to the antenna, thereby alternately to permit transmission or reception of signals generated by, or received by the radiotelephone. Because circuits disposed upon ceramic materials are of low insertion losses, the switch circuit is advantageously utilized to form a portion of the radiotelephone.

Claims

1. A switch circuit for a transceiver having a transmitter circuitry and a receiver circuitry, said switch circuit positionable responsive to levels of a control signal applied thereto for connecting alternately the transmitter circuitry to a transceiver antenna or the receiver circuitry to the transceiver antenna, said switch circuit comprising:

a DC blocking capacitor formed on the first and second ceramic substrates, a first side portion of said DC blocking capacitor for interconnection with a first side portion of the transceiver antenna;

a receiver circuit path interconnecting the receiver circuitry and a second side portion of the DC blocking capacitor wherein, depending upon the levels of the control signal, said receiver circuit path includes a shunt path as a portion thereof and wherein said receiver circuit path includes a receiver-side stripline transmission line formed upon a third ceramic substrate, a first ground plane adjacent to one side of the third ceramic substrate, and a second ground plane adjacent to an opposing side of the third ceramic substrate, wherein one of said first and second ground planes is formed on an adjacent ceramic substrate, wherein said receiver-side stripline transmission line is of a length substantially corresponding to one-quarter a wavelength of signals to be received at the transceiver antenna;

a transmitter circuit path interconnecting the transmitter circuitry and the second side portion of the DC blocking Capacitor wherein said transmitter circuit path is of electrical characteristics dependent upon the levels of the control signal; and

a control-signal stripline transmission line formed upon the same third ceramic substrate and coupled to said transmitter circuit path to apply the control signal to the transmitter circuit path to cause the transmitter circuit path to form a low impedance path to connect electrically the transmitter circuitry and the transceiver antenna and also to cause the shunt path to form a portion of said receiver circuit path, thereby to disconnect electrically the receiver circuitry from the transceiver antenna only during times when the control signal is above a first signal level and, otherwise to cause the transmitter circuit path to form a high impedance path to disconnect electrically the transmitter circuitry from the transceiver antenna and also to disconnect the shunt path from the receiver circuit path, thereby to connect electrically the receiver circuitry and the transceiver antenna, wherein said control-signal stripline transmission line is of a length substantially corresponding to one-quarter a wavelength of signals to be transceived at the transceiver antenna.

2. The switch circuit of claim 1 wherein said transmitter circuit path includes a diode positioned in-line between the transmitter circuitry and the transceiver antenna, said diode operative to form a low impedance path when the control signal is above the first signal level and, otherwise, to form a high impedance circuit path.

3. The switch circuit of claim 2 wherein said transmitter circuit path includes a capacitor of a component value to form a second DC blocking capacitor thereof positioned in-line between the transmitter circuitry and the diode.

4. The switch circuit of claim 3 wherein the control-signal stripline transmission line is coupled to the transmitter circuit path at a location between the diode and the second DC blocking capacitor.

5. The switch circuit of claim 1 wherein said receiver-side stripline transmission line is operatively positioned in-line between the receiver circuitry and the transceiver antenna.

6. The switch circuit of claim 5 wherein the shunt path of the receiver circuit path is comprised of a diode configured in a shunt connection with the receiver circuitry, said diode comprising the shunt path operative to form a low impedance path when the control signal is above the first signal level and, otherwise, to form a high impedance path.

7. The switch circuit of claim 6 wherein said receiver circuit path includes a capacitor of a component value to form a second DC blocking capacitor thereof positioned in-line between the receiver circuitry and the receiver-side stripline transmission line.

10. The switch circuit of claim 1 wherein a portion of said receiver circuit path is disposed on a fourth ceramic substrate.

8. The switch circuit of claim 8 wherein the diode comprising the shunt path is positioned between the second DC blocking capacitor and the receiver-side stripline transmission line.

9. The switch circuit of claim I wherein at least a portion of said transmitter circuit path is disposed upon a fourth ceramic substrate.

11. A switch circuit disposed upon a plurality of tandemly-positioned ceramic substrates, said switch circuit for a transceiver having a transmitter circuit and a receiver circuit and positionable responsive to levels of a control signal applied thereto for connecting alternately the transmitter circuitry to a transceiver antenna or the receiver circuitry to the transceiver antenna, said switch circuit comprising:

a DC blocking capacitor formed on the first and second ceramic substrates of the tandemly-positioned substrates, a first side portion of said DC blocking capacitor for interconnection with a first side portion of the transceiver antenna;

a receiver circuit path interconnecting the receiver circuitry and a second side portion of the DC blocking capacitor, said receiver circuit path having receiver circuit path elements also disposed upon various plate members of a plurality of tandemly-positioned plate members wherein, depending upon the levels of the control signal, the receiver circuit path further includes a shunt path as a portion thereof and wherein said receiver circuit path includes a receiver-side stripline transmission line of one-quarter wavelength of signals to be received, formed upon a third ceramic substrate of the tandemly-positioned substrates, a first ground plane opposite the receiver-side stripline transmission line and adjacent to one side of the third ceramic substrate, and a second ground plane opposite the receiver-side stripline transmission line adjacent to an opposing side of the third ceramic substrate, wherein one of said first and second ground planes is formed on an adjacent ceramic substrate;

a transmitter circuit path interconnecting the transmitter circuitry and the first side portion of the transceiver antenna, said transmitter circuit path having transmitter circuit elements disposed on various ceramic substrates of the plurality of tandemly-positioned substrates, wherein said transmitter circuit path is of electrical characteristics dependent upon the levels of the control signal; and

a control-signal stripline transmission line of one-quarter wavelength of the signals to be transceived, formed upon the same third ceramic substrate, the first ground plane opposite the control-signal stripline transmission line and the second ground plane opposite the control-signal stripline transmission line coupled to said transmitter circuit path for applying the control signal to the transmitter circuit path to cause the transmitter circuit path to form a short circuit to connect electrically the transmitter circuitry and the transceiver antenna and also to cause the shunt path to form a portion of said receiver circuit path, thereby to disconnect electrically the receiver circuitry from the transceiver antenna only during times when the control signal is above a first signal level and, otherwise to cause the transmitter circuit path to form an open circuit to disconnect electrically the transmitter circuitry from the transceiver antenna and also to disconnect the shunt path from the receiver circuit path, thereby to connect electrically the receiver circuitry and the transceiver antenna.