Differential PLL with charge pump chopping

Patent metadata

Field	Value
Publication number	US-10141941-B2
Application number	US-201715683374-A
Country	US
Kind code	B2
Filing date	Aug 22, 2017
Priority date	Dec 30, 2016
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

According to a first example aspect there is provided a charge pump circuit that includes a first chopper circuit configured to switch first and second chopper circuit outputs between first and second chopper circuit inputs at a chopping frequency, wherein successive input signals at the first chopper circuit input are output alternatively at the first and second chopper circuit outputs in successive cycles of the chopping frequency and successive input signals at the second chopper circuit input are output alternatively at the second and first chopper circuit outputs in successive cycles of the chopping frequency. A differential charge pump is configured to receive the signals output from the first and second chopper circuit outputs and produce corresponding first and second charge pumped signals.

First claim

What is claimed is:

1. A charge pump circuit comprising:
an intake chopper circuit configured to switch input signals received at the first and second inputs of the intake chopper circuit between first and second outputs of the intake chopper circuit at a chopping frequency, wherein successive input signals at the first input are provided alternatively at the first and second outputs in successive cycles of the chopping frequency and successive input signals at the second input are provided alternatively at the second and first outputs in successive cycles of the chopping frequency;
a differential charge pump configured to receive the signals from the first and second outputs of the intake chopper circuit and produce corresponding first and second charge pumped signals; and
an output chopper circuit configured to receive the first and second charge pumped signals at respective first and second inputs, provide the first charge pumped signals alternatively at first and second outputs in successive cycles of the chopping frequency, and provide the second charge pumped signals alternatively at the second and first outputs in successive cycles of the chopping frequency.

2. The charge pump circuit of claim 1 wherein:
the differential charge pump includes: (i) an integral charge pump path configured to receive signals from the first and second outputs of the intake chopper circuit and provide corresponding first and second integral charge pumped signals as the first and second charge pumped signals; and (ii) a proportional charge pump path configured to receive signals from the first and second outputs of the intake chopper circuit and provide corresponding first and second proportional charge pumped signals;
the output chopper circuit includes: (i) an integral path chopper circuit configured to switch the first and second integral charge pumped signals between first and second integral path chopping circuit outputs at the chopping frequency; and (ii) a proportional path chopper circuit configured to switch the first and second proportional charge pumped signals between first and second proportional path chopping circuit outputs at the chopping frequency.

3. The charge pump circuit of claim 2 wherein in successive cycles of the chopping frequency:
the integral path chopper circuit receives alternating positive and negative integral charge pumped signals at a first input and alternating negative and positive integral charge pumped signals at a second input, and provides successive positive integral charge pumped signals at a first output and provides successive negative integral charge pumped signals at a second output;
the proportional path chopper circuit receives alternating positive and negative proportional charge pumped signals at a first input and alternating negative and positive proportional charge pumped signals at a second input, and provides successive positive proportional charge pumped signals at a first output and provides successive negative proportional charge pumped signals at a second output.

4. The charge pump circuit of claim 2 wherein the intake charge pump, integral charge pump path and proportional charge pump path each comprise a butterfly switch circuit configured to switch a pair of inputs between a pair of outputs at the chopping frequency.

5. The charge pump circuit of claim 2 wherein the proportional charge pump path is an N scaled replica of the integral charge pump path where 10<=N<=40.

6. The charge pump circuit of claim 1 wherein:
the first input of the intake chopper circuit receives successive pull-up signals from a phase frequency detector and the second input of the intake chopper circuit receives successive pull-down signals from the phase frequency detector, the first and second outputs of the intake chopper circuit providing first and second output signals that each comprise alternating pull-up and pull-down signals.

7. The charge pump circuit of claim 1 wherein the output chopper circuit up-converts flicker noise introduced by the differential charge pump path to the chopping frequency, the chopping frequency being selected to exceed a corner frequency of the flicker noise.

8. A method of applying charge pumping signals, comprising:
at an intake chopper, switching successive input signals received at a first input alternatively between first and second outputs in successive cycles of a chopping frequency and switching successive input signals at a second input alternatively between the second and first outputs in the successive cycles;
charge pumping the signals output from the first and second outputs to produce corresponding first and second charge pumped signals; and
at an output chopper, receiving the first and second charge pumped signals at respective first and second inputs, providing the first charge pumped signals alternatively at first and second outputs in successive cycles of the chopping frequency, and providing the second charge pumped signals alternatively at the second and first outputs in successive cycles of the chopping frequency.

9. The method of claim 8 , wherein:
the charge pumping includes: (i) using an integral charge pump path to receive signals from the first and second outputs of the intake chopper circuit and provide corresponding first and second integral charge pumped signals as the first and second charge pumped signals; and (ii) using a proportional charge pump path to receive the signals from the first and second outputs of the intake chopper circuit and provide corresponding first and second proportional charge pumped signals; and
the receiving and outputting at the output chopper comprises: (i) using an integral path chopper circuit to switch the first and second integral charge pumped signals between first and second integral path chopping circuit outputs at the chopping frequency; and (ii) using a proportional path chopper circuit to switch the first and second proportional charge pumped signals between first and second proportional path chopping circuit outputs at the chopping frequency.

10. The method of claim 9 wherein in successive cycles of the chopping frequency:
the integral path chopper circuit receives alternating positive and negative integral charge pumped signals at a first input and alternating negative and positive integral charge pumped signals at a second input, and outputs successive positive integral charge pumped signals at a first output and outputs successive negative integral charge pumped signals at a second output;
the proportional path chopper circuit receives alternating positive and negative proportional charge pumped signals at a first input and alternating negative and positive proportional charge pumped signals at a second input, and outputs successive positive proportional charge pumped signals at a first output and outputs successive negative proportional charge pumped signals at a second output.

11. The method of claim 8 wherein:
the first input of the intake chopper receives successive pull-up signals from a phase frequency detector and the second input of the intake chopper receives successive pull-down signals from the phase frequency detector, the first and second outputs of the intake chopper providing first and second output signals that each comprise alternating pull-up and pull-down signals.

12. The method of claim 8 wherein the switching at the intake chopper up-converts the input signals to the chopping frequency, and the switching at the output chopper: (i) down-converts a spectrum of the first and second charge pumped signals corresponding to the spectrum of the input signals from the chopping frequency; and (ii) up-converts flicker noise introduc

Assignees

• Petrov Dmitry
• Huawei Tech Co Ltd

Inventors

• Petrov Dmitry

Classifications

• H04L27/0014

  Carrier regulation (of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657) · CPC title

• H03L7/0896

  the current generators being controlled by differential up-down pulses · CPC title

• H03L7/0891 Primary

  the up-down pulses controlling source and sink current generators, e.g. a charge pump · CPC title

• H04L25/0272

  Arrangements for coupling to multiple lines, e.g. for differential transmission · CPC title

• H04L2027/0053

  Closed loops · CPC title