Variable frequency circuit in attenuator and/or negative voltage generator

Patent metadata

Field	Value
Publication number	US-2016359471-A1
Application number	US-201615238473-A
Country	US
Kind code	A1
Filing date	Aug 16, 2016
Priority date	Mar 25, 2011
Publication date	Dec 8, 2016
Grant date	—

Abstract

Apparatus and methods for distributing spurious tones through the frequency domain are disclosed. One such apparatus can include a dithering circuit configured to generate a sequence of numbers that exhibit statistical randomness and a variable frequency circuit configured to adjust a frequency of an output based on the sequence of numbers so as to spread energy of spurious tones in a frequency response of the output to lower a noise floor. In one example, spurious tones can be reduced in a negative voltage generator of a radio frequency (RF) attenuator.

First claim

1 . (canceled)

2 . A radio frequency attenuator comprising:
a controller including a variable frequency circuit configured to spread energy of spurious tones through a frequency domain of an output, the controller further including a buffer configured to receive the output of the variable frequency circuit and to generate differential signals, and the controller configured to generate a control signal based on the differential signals; and an attenuator component in communication with the controller, the attenuator component configured to attenuate a radio frequency signal based on the control signal.

3 . The radio frequency attenuator of claim 2 wherein the controller indudes a dithering circuit configured to provide an output sequence that exhibits statistical randomness to the variable frequency circuit.

4 . The radio frequency attenuator of claim 3 wherein the controller includes a charge pump configured to receive the differential signals from the buffer.

5 . The radio frequency attenuator of claim 4 wherein an output of the charge pump is a negative voltage that is maintained below zero Volts.

6 . The radio frequency attenuator of claim 3 wherein the dithering circuit is configured to use a signal of the differential signals as a clock signal.

7 . The radio frequency attenuator of claim 2 wherein the buffer is configured to receive the output of the variable frequency circuit as a single-ended input.

8 . The radio frequency attenuator of claim 7 wherein the controller includes a charge pump configured to receive the differential signals from the buffer, and the control signal is based on an output of the charge pump.

9 . The radio frequency attenuator of claim 8 wherein the controller includes a dithering circuit configured to provide an input sequence to the variable frequency circuit.

10 . The radio frequency attenuator of claim 2 wherein the controller includes a level shifter configured to generate the control signal.

11 . The radio frequency attenuator of claim 2 wherein the attenuator component is a digital step attenuator component.

12 . The radio frequency attenuator of claim 2 wherein the a enua or component and the controller are implemented on a single integrated circuit.

13 . A negative voltage generator comprising:
a variable frequency circuit configured to generate an output having energy of spurious tones spread through a frequency domain; a buffer configured to receive the output of the variable frequency circuit as a single-ended input and to generate differential signals; and a charge pump configured to generate a negative voltage based on the differential signals generated by the buffer.

14 . The negative voltage generator of claim 13 further comprising a dithering circuit configured to provide an input sequence that exhibits statistical randomness to the variable frequency circuit.

15 . The negative voltage generator of claim 14 wherein a clock signal of t dithering circuit is provided by the buffer.

16 . The negative voltage generator of claim 15 wherein the variable frequency circuit includes a variable oscillator.

17 . The negative voltage generator of claim 14 wherein the variable frequency circuit includes an oscillator, and a clock signal of the dithering circuit is based on an output of the oscillator.

18 . An electronically-implemented method of generating a negative voltage with reduced spurious tones, the method comprising:
distributing spurious tones through a frequency domain of a variable frequency signal; buffering the variable frequency signal to provide differential signals; and generating the negative voltage with reduced spurious tones based on the differential signals.

19 . The electronically-implemented method of claim 18 further comprising providing an input sequence that exhibits statistical randomness to a variable frequency circuit configured to generate the variable frequency signal.

20 . The electronically-implemented method of claim 19 wherein the providing is performed by a dithering circuit configured to use a signal of the differential signals as a clock signal.

21 . The electronically-implemented method of claim 18 wherein the generating is performed using a charge pump that is in communication with a variable frequency circuit by way of a buffer arranged to perform the buffering.

Assignees

• Skyworks Solutions Inc

Inventors

• Obkircher Thomas
• Domino William J
• Agarwal Bipul

Classifications

• H03H11/24 Primary

  Frequency-independent attenuators · CPC title

• H02M3/07

  using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps} · CPC title

• H03F3/21

  with semiconductor devices only {(H03F3/245 takes precedence)} · CPC title

• H03B5/24

  active element in amplifier being semiconductor device (H03B5/26 takes precedence) · CPC title

• H04W28/14

  using intermediate storage · CPC title