Tuning Range Enhancement by Negative Resistance

Patent metadata

Field	Value
Publication number	US-2025070714-A1
Application number	US-202418800608-A
Country	US
Kind code	A1
Filing date	Aug 12, 2024
Priority date	Jan 30, 2019
Publication date	Feb 27, 2025
Grant date	—

Abstract

A tank circuit includes a tunable resonator subcircuit having an effective parallel resistance that varies with tuning of the tunable resonator subcircuit. The tank circuit further comprises a variable negative-resistance subcircuit coupled in parallel to the tunable resonator subcircuit, where the variable negative-resistance subcircuit is configured to provide a variable negative resistance, so as to increase the effective parallel resistance of the tank circuit. A control circuit is configured to increase the negative resistance presented by the variable negative-resistance subcircuit in response to a change in the tunable resonator subcircuit that lowers the resonant frequency of the tunable resonator subcircuit.

First claim

1 . A tank circuit, comprising:
a tunable resonator subcircuit having an effective parallel resistance that varies with tuning of the tunable resonator subcircuit; and a variable negative-resistance subcircuit coupled in parallel to the tunable resonator subcircuit, wherein the variable negative-resistance subcircuit is configured to provide a variable negative resistance, and a control circuit wherein the control circuit is configured to increase the negative resistance presented by the variable negative-resistance subcircuit in response to a change in the tunable resonator subcircuit that lowers the resonant frequency of the tunable resonator subcircuit.

2 . The tank circuit of claim 1 , wherein the variable negative-resistance subcircuit is configured to selectably present one of two or more negative resistance states, responsive to a digital control input, so as to provide a negative resistor bank.

3 . The tank circuit of claim 2 , wherein one of the two or more negative resistance states is a state in which no negative resistance is presented by the negative-resistance subcircuit.

4 . The tank circuit of claim 2 , wherein the variable negative-resistance subcircuit is configured to selectably present one of sixteen negative resistance states, responsive to a 4-bit digital control input.

5 . The tank circuit of claim 1 , wherein the tunable resonator subcircuit comprises a switchable capacitor bank connected in parallel with a transformer or inductor, and wherein the variable negative-resistance subcircuit is connected in parallel with the switchable capacitor bank.

6 . The tank circuit of claim 1 , wherein the variable negative-resistance subcircuit comprises cross-coupled common source transistors, each having a transconductance and each controlled by a bias input to each gate of the common source transistors.

7 . A wireless device comprising the transceiver circuit of claim 1 .

8 . A method for providing a variable resonance in a tank circuit comprising a tunable resonator subcircuit, the tunable resonator subcircuit, having an effective parallel resistance that varies with tuning of the tunable resonator subcircuit, and a variable negative-resistance subcircuit coupled in parallel to the tunable resonator subcircuit, the method comprising:
tuning a resonant frequency of the tunable resonator subcircui; and controlling the variable negative-resistance subcircuit to increase the effective parallel resistance of the tank circuit, in response to a change in the tunable resonator subcircuit that lowers the resonant frequency of the tunable resonator subcircuit.

9 . The method of claim 8 , wherein said controlling the variable negative-resistance subcircuit comprises selecting one of two or more negative resistance states for the variable negative-resistance subcircuit, using the digital control input, so as to select a negative resistance from a negative resistor bank.

10 . The method of claim 9 , wherein one of the two or more negative resistance states is a state in which no negative resistance is presented by the negative-resistance subcircuit.

11 . The method of claim 9 , wherein said controlling the variable negative-resistance subcircuit comprises selecting one of sixteen negative resistance states for the variable negative-resistance subcircuit, using the 4-bit digital control input.

12 . The method of claim 9 , wherein the tunable resonator subcircuit comprises a switchable capacitor bank connected in parallel with a transformer or inductor, wherein the switchable negative-resistance subcircuit is connected in parallel with the switchable capacitor bank, and wherein tuning the tunable resonator subcircuit comprises selecting one of two or more selectable capacitances, using a control input to the tunable resonator subcircuit.

13 . The method of claim 9 , wherein the variable negative-resistance subcircuit comprises cross-coupled common source transistors, each of the cross-coupled common-source transistors having a transconductance and each controlled by a bias input its respective gate.

Assignees

• Ericsson Telefon Ab L M

Inventors

• Özdemir Ufuk
• Caputa Peter
• Özen Mustafa
• Mahmoud Ahmed

Classifications

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• H03F2200/165

  A filter circuit coupled to the input of an amplifier · CPC title

• H03F3/245

  with semiconductor devices only · CPC title

• H03B5/1228

  the amplifier comprising one or more field effect transistors · CPC title

• H03B5/1265

  switched capacitors · CPC title