Variable attenuator system and method

• US 7,184,731 B2
• Filed: 11/10/2003
• Issued: 02/27/2007
• Est. Priority Date: 11/12/2002
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kim, Gi Mun
• Primary Examiner(s): Urban; Edward F.
• Assistant Examiner(s): Jackson; Blane J.
• Application Number:
  US10/705,518
• Publication Number:
  US 20040157575A1
• Time in Patent Office: 1,205 Days
• Field of Search: 455/249.1, 455/289, 327/314, 327/308, 333/81.R, 333/32, 333/103
• US Class Current: 455/249.1
• CPC Class Codes: H03G 1/0058 PIN-diodes

Abstract

A variable attenuator comprising a first attenuator for attenuating a RF signal according to a fixed voltage, a second attenuator connected in parallel to the first attenuator and attenuating the RF signal according to a control voltage for determining an attenuation mode, and a first impedance matching unit for maintaining input/output impedance matching of the second attenuator.

Claims

1. A variable attenuator comprising:

a first attenuator for attenuating a RF signal according to a fixed voltage;

a second attenuator connected in parallel to the first attenuator and attenuating the RF signal according to a control voltage for determining an attenuation mode; and

a first impedance matching unit for maintaining input/output impedance matching of the second attenuator,

wherein the second attenuator comprises;

a third capacitor connected in parallel to an input terminal of the first attenuator,

a first diode for attenuator the RF signal transmitted through the third capacitor, and

a second diode connected in parallel to an output terminal of the first attenuator.

2. The attenuator of claim 1, further comprising:

a second impedance matching unit for maintaining input/output impedance matching of the first attenuator.

3. The attenuator of claim 1, further comprising:

a first capacitor for removing serial current elements from an input RF signal and for providing the RF signal to the first attenuator; and

a second capacitor for removing serial current elements from an output signal of the first and second attenuators.

4. The attenuator of claim 1, wherein the first attenuator comprises a diode.

5. The attenuator of claim 1, wherein the fixed voltage is a power voltage divided by a certain level.

6. The attenuator of claim 1, wherein the RF signal flows to the first attenuator in a low attenuation mode.

7. The attenuator of claim 1, wherein the RF signal flows to the second attenuator in a high attenuation mode.

8. The attenuator of claim 1, wherein the RF signal flows to the first and second attenuators in an intermediate attenuation mode.

9. The attenuator of claim 1, wherein the second attenuator comprises a first and a second resistance means connected in serial between anodes of the first and second diodes.

10. The attenuator of claim 9, wherein the second attenuator comprises a control voltage input terminal is provided between the first and second resistance means.

11. A variable attenuator comprising:

a first attenuator for attenuating a RF signal according to a first voltage;

a first impedance matching unit for maintaining impedance matching of the first attenuator in a low attenuation mode;

a second attenuator provided between input and output terminals of the first attenuator for attenuating the RF signal according to a control voltage for determining an attenuation mode,

wherein the second attenuator comprises;

a third capacitor connected in parallel to an input terminal of the first attenuator for cutting off a control voltage to the first attenuator;

a first diode for attenuating the RE signal transmitted through the third capacitor;

a second diode connected in parallel to an output terminal of the first attenuator; and

first and second resistance means corrected to anodes of the first and second diodes for applying the control voltage; and

a second impedance matching unit for maintaining input/output impedance matching of the second attenuator in a high attenuation mode,

wherein the second impedance matching unit comprises at least two resistors provided between the second attenuator and a ground connection.

12. The attenuator of claim 11, wherein die first and second impedance matching units have the same resistance.

13. The attenuator of claim 11, wherein the at least two resistors each have a resistance of 50Ω

.

14. The attenuator of claim 11, wherein the RF signal flows to the first attenuator in a low attenuation mode and flows to the second attenuator in a high attenuation mode.

15. The attenuator of claim 11, wherein the RF signal flows to the first and second attenuators in an intermediate attenuation mode.

16. A variable attenuator comprising:

a first diode for attenuating a RF signal according to a first voltage;

a second diode, connected in parallel to an anode of the first diode for attenuating the RF signal, according to a control voltage;

a third diode connected in parallel to a cathode of the first diode for attenuating the RF signal, according to the control voltage;

a first resistor provided between a cathode of the second diode and a ground connection; and

a second resistor provided between a cathode of the third diode and the ground connection.

17. The attenuator of claim 16, further comprising:

a capacitor connected to the anode of the first diode for cutting off a control voltage provided to the first diode.

18. The attenuator of claim 16, further comprising:

third and fourth resistors for applying the control voltage to the anodes of the second and third diodes, respectively.

19. The attenuator of claim 16, wherein the first and second resistors are approximately 50Ω

.

20. The attenuator of claim 16, wherein the RF signal flows to the first diode, in a low attenuation mode.

21. The attenuator of claim 16, wherein the RF signal flows to the second and third diodes in a high attenuation mode.

22. The attenuator of claim 16, wherein the RF signal flows to the first, second, and third diodes, in an intermediate attenuation mode.

23. A variable attenuator comprising:

a first attenuator for attenuating a RF signal according to a fixed voltage;

a second attenuator connected in parallel to the first attenuator and attenuating the RF signal according to a control voltage for determining an attenuation mode; and

a first impedance matching unit for maintaining input/output impedance matching of the second attenuator,

wherein the second attenuator comprises;

a first diode connected in parallel to an input terminal of the first attenuator; and

a second diode connected in parallel to an output terminal of the first attenuator

a third capacitor connected in parallel to an input terminal of the fist attenuator;

wherein the first diode attenuates the RF signal transmitted through the third capacitor.