Frequency-dependent resistor and circuitry employing the same

Patent metadata

Field	Value
Publication number	US-9972425-B2
Application number	US-201514946028-A
Country	US
Kind code	B2
Filing date	Nov 19, 2015
Priority date	Jun 30, 2015
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

A frequency-dependent resistor and circuitry employing the same are provided. In some embodiments, a resistor includes a substrate, an input port, an output port, and a conductive trace on the substrate between the input port and the output port. A resistance between the input port and the output port for a low frequency signal is at least five times lower than the resistance between the input port and the output port for an RF signal and the ratio of the frequencies of the RF signal to the low frequency signal is at least fifty. Circuitry including a transistor adapted to selectively couple the input to the output in response to a control signal provided via a resistor with resistance for a low frequency signal at least five times lower than resistance for an RF signal will have a reduced switching time while still isolating the RF signal.

First claim

What is claimed is:

1. A resistor comprising:
a substrate;
an input port;
an output port; and
a conductive trace on the substrate between the input port and the output port;
wherein a resistance between the input port and the output port for a low frequency signal is at least five times lower than the resistance between the input port and the output port for a radio frequency (RF) signal and a ratio of a frequency of the RF signal to the low frequency signal is at least fifty.

2. The resistor of claim 1 , wherein the resistance between the input port and the output port for a signal at or below 10 Megahertz (MHz) is at most 10 kilohms (kΩ), and the resistance between the input port and the output port for a signal at or above 1 gigahertz (GHz) is at least 100 kΩ.

3. The resistor of claim 1 , wherein the conductive trace has a relative magnetic permeability of at least 100.

4. The resistor of claim 3 , wherein the conductive trace has a relative magnetic permeability of at least 1000.

5. The resistor of claim 1 , wherein the conductive trace comprises one of Iron, Cobalt, and Nickel.

6. The resistor of claim 5 , wherein the conductive trace comprises Cobalt.

7. The resistor of claim 1 , wherein the conductive trace is a thin film.

8. The resistor of claim 1 , wherein the conductive trace is a meander line on the substrate.

9. Circuitry comprising:
at least one transistor with an input coupled to a source of the at least one transistor and an output coupled to a drain of the at least one transistor;
wherein the at least one transistor is adapted to selectively couple the input to the output in response to a control signal provided via at least one resistor and the at least one resistor has a resistance for a low frequency signal at least five times lower than the resistance for a Radio Frequency (RF) signal and a ratio of a frequency of the RF signal to the low frequency signal is at least fifty.

10. The circuitry of claim 9 , wherein the input of the at least one transistor is connected to an incoming RF port and the output of the at least one transistor is connected to an outgoing RF port; and the circuitry further comprises:
at least one second transistor with an input coupled to a source of the at least one second transistor and an output coupled to a drain of the at least one second resistor wherein:
the at least one second transistor is adapted to selectively couple the input to the output in response to a second control signal provided via at least one second resistor and the at least one second resistor has a resistance for the low frequency signal at least five times lower than the resistance for the RF signal;
the input of the at least one second transistor is connected to the incoming RF port; and
the output of the at least one second transistor is connected to a ground.

11. The circuitry of claim 9 , wherein a resistance-capacitance (RC) time constant of the at least one transistor and the at least one resistor is less than or equal to 10 microseconds (μs).

12. The circuitry of claim 9 , wherein the at least one resistor has the resistance for a signal at or below 10 megahertz (MHz) that is at most one-tenth the resistance for a signal at or above 1 gigahertz (GHz).

13. The circuitry of claim 12 , wherein the at least one resistor has the resistance for a signal at or below 10 MHz that is at most 10 kilohms (kΩ) and the resistance for a signal at or above 1 GHz is at least 100 kΩ.

14. The circuitry of claim 9 , wherein the at least one resistor comprises one of Iron, Cobalt, and Nickel.

15. The circuitry of claim 14 , wherein the at least one resistor comprises Cobalt.

16. The circuitry of claim 9 , wherein the at least one resistor comprises a thin film.

17. A radio frequency (RF) transmitter comprising:
modulator circuitry configured to receive a baseband signal and provide an RF input signal;
an amplifier configured to receive and amplify the RF input signal to provide an RF output signal; and
front end circuitry configured to receive the RF output signal and provide the RF output signal to an antenna for transmission comprising at least one RF circuitry;
wherein the at least one RF circuitry comprises:
at least one transistor with an input coupled to a source of the at least one transistor and an output coupled to a drain of the at least one transistor;
wherein the at least one transistor is adapted to selectively couple the input to the output in response to a control signal provided via at least one resistor and the at least one resistor has a resistance for a low frequency signal at least five times lower than the resistance between an input port and an output port for an RF signal and a ratio of a frequency of the RF signal to the low frequency signal is at least fifty.

18. The RF transmitter of claim 17 , wherein a resistance-capacitance (RC) time constant of the at least one transistor and the at least one resistor in the RF circuitry is less than or equal to 10 microseconds (μs).

19. The RF transmitter of claim 17 , wherein the at least one resistor in the RF circuitry comprises one of Iron, Cobalt, and Nickel.

20. The RF transmitter of claim 19 , wherein the at least one resistor in the RF circuitry comprises Cobalt.

Assignees

• Rf Micro Devices Inc
• Qorvo Us Inc

Inventors

• Wright Peter V
• Burger Kerry

Classifications

• H01C1/01

  Mounting; Supporting · CPC title

• H04B1/0475

  with means for limiting noise, interference or distortion (H04B1/0483 takes precedence) · CPC title

• H03H7/52

  One-way transmission networks, i.e. unilines · CPC title

• H01C7/006 Primary

  Thin film resistors · CPC title

• H03H7/465

  having variable circuit topology, e.g. including switches · CPC title