# US 2013/0154725 A1 · Charge domain filter and method thereof

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- Number: US 2013/0154725 A1
- Document ID: US20130154725A1
- Status: Published application
- Kind: A1
- Application number: 13/364,245
- Filed: 2012-02-01
- Published: 2013-06-20
- Earliest claimed: 2011-12-14
- Assignees: Industrial Technology Research Institute
- Inventors: Ming-Feng Huang
- Web page: https://patentgrep.com/patent/US20130154725A1

## CPC

- H03H 19/004: {Switched capacitor networks}
- H03H 15/023: {with parallel-input configuration}
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)

## Abstract

A charge domain filter (CDF) and a method thereof are provided. The CDF includes an amplifier, a first switch-capacitor network (SCN), a second SCN, a third SCN and a fourth SCN. Input terminals of the first and the second SCNs are coupled to first and second output terminals of the amplifier, respectively. Input and output terminals of the third SCN are coupled to output terminals of the first and the second SCNs, respectively. Input and output terminals of the fourth SCN are coupled to output terminals of the second and the first SCNs, respectively. A mode control terminal of the third SCN receives a first mode signal to set an impulse response mode of the third SCN. A mode control terminal of the fourth SCN receives a second mode signal to set an impulse response mode of the fourth SCN.

## Claims

### Claim 1

A charge domain filter (CDF), comprising:
an amplifier, comprising a first output terminal and a second output terminal;
at least one first switch-capacitor network (SCN), comprising an input terminal coupled to the first output terminal of the amplifier;
at least one second SCN, comprising an input terminal coupled to the second output terminal of the amplifier;
at least one third SCN, wherein an input terminal of the third SCN is coupled to an output terminal of the first SCN, an output terminal of the third SCN is coupled to an output terminal of the second SCN, and a mode control terminal of the third SCN receives a first mode signal to set an impulse response mode of the third SCN; and
at least one fourth SCN, wherein an input terminal of the fourth SCN is coupled to the output terminal of the second SCN, an output terminal of the fourth SCN is coupled to the output terminal of the first SCN, and a mode control terminal of the fourth SCN receives a second mode signal to set an impulse response mode of the fourth SCN.

### Claim 2 (depends on 1)

The CDF according to claim 1, wherein the amplifier is a transconductance amplifier or an operation amplifier.

### Claim 3 (depends on 1)

The CDF according to claim 1, wherein the impulse response modes of the third SCN and the fourth SCN comprise an infinite impulse response (IIR) mode or a finite impulse response (FIR) mode, and the first SCN and the second SCN support a FIR filter or an IIR filter.

### Claim 4 (depends on 3)

The CDF according to claim 3, wherein in the FIR mode, the third SCN and the fourth SCN provide required frequency responses to equalize the amplitude at a specific frequency.

### Claim 5 (depends on 3)

The CDF according to claim 3, wherein the IIR modes of the third SCN and the fourth SCN are enabled to adjust the level of the amplitude.

### Claim 6 (depends on 1)

The CDF according to claim 1, wherein sampling rates of the third SCN and the fourth SCN are made to be different from sampling rates of the first SCN and the second SCN, so as to modulate an equalized frequency of the CDF.

### Claim 7 (depends on 1)

The CDF according to claim 1, wherein sub SCNs inside the first SCN, the second SCN, the third SCN and the fourth SCN perform time-interleaving operations to reduce a folding frequency, filter clock feed-through from the sub SCNs, and mitigate Sinc-function distortion.

### Claim 8 (depends on 1)

The CDF according to claim 1, wherein a network of the first SCN, the second SCN, the third SCN and the fourth SCN comprises:
a plurality of sampling units, wherein sampling terminals of the plurality of sampling units are coupled to the input terminal of the network, and the plurality of sampling units sample the input terminals of the network through different phases, respectively; and
a summation unit, wherein an input terminal of the summation unit is coupled to output terminals of the plurality of sampling units, and the summation unit summates sampling results of the plurality of sampling units.

### Claim 9 (depends on 8)

The CDF according to claim 8, wherein one of the plurality of sampling units comprises:
a sampling switch, comprising a first terminal coupled to the input terminal of the network;
a sampling capacitor, coupled to a second terminal of the sampling switch;
a reset switch, wherein a first terminal of the reset switch is coupled to the sampling capacitor, and a second terminal of the reset switch is coupled to a reference voltage; and
an output switch, wherein a first terminal of the output switch is coupled to the sampling capacitor, and a second terminal of the output switch is coupled to the input terminal of the summation unit.

### Claim 10 (depends on 8)

The CDF according to claim 8, wherein the summation unit comprises:
a summation capacitor, coupled to the output terminals of the plurality of sampling units.

### Claim 11 (depends on 10)

The CDF according to claim 10, wherein the summation unit further comprises:
a first switch, wherein a first terminal of the first switch is coupled to the output terminals of the plurality of sampling units; and
a first capacitance, coupled to a second terminal of the first switch.

### Claim 12 (depends on 10)

The CDF according to claim 10, wherein the summation unit further comprises:
a second switch, wherein a first terminal of the second switch is coupled to the summation capacitor; and
a third switch, wherein a first terminal of the third switch is coupled to a second terminal of the second switch, a second terminal of the third switch is coupled to a reference voltage, and a control terminal of the third switch receives a mode signal.

### Claim 13 (depends on 8)

The CDF according to claim 8, wherein one of the plurality of sampling units comprises:
a sampling switch, wherein a first terminal of the sampling switch is coupled to the input terminal of the network;
a sampling capacitor, coupled to a second terminal of the sampling switch;
a first switch, comprising a first terminal coupled to the sampling capacitor;
a first capacitor, coupled to a second terminal of the first switch;
a reset switch, comprising a first terminal coupled to the sampling capacitor;
a second switch, wherein a first terminal of the second switch is coupled to a second terminal of the reset switch, a second terminal of the second switch is coupled to a reference voltage, and a control terminal of the second switch receives a mode signal; and
an output switch, wherein a first terminal of the output switch is coupled to the sampling capacitor, and a second terminal of the output switch is coupled to the input terminal of the summation unit.

### Claim 14 (depends on 8)

The CDF according to claim 8, wherein one of the plurality of sampling units comprises:
a first sampling switch, comprising a first terminal coupled to the input terminal of the network;
a first sampling capacitor, coupled to a second terminal of the first sampling switch;
a first reset switch, wherein a first terminal of the first reset switch is coupled to the first sampling capacitor, and a second terminal of the first reset switch is coupled to a reference voltage;
a second sampling switch, wherein a first terminal of the second sampling switch is coupled to the first sampling capacitor;
a second sampling capacitor, coupled to a second terminal of the second sampling switch;
a second reset switch, wherein a first terminal of the second reset switch is coupled to the second sampling capacitor, and a second terminal of the second reset switch is coupled to the reference voltage; and
an output switch, wherein a first terminal of the output switch is coupled to the second sampling capacitor, and a second terminal of the output switch is coupled to the input terminal of the summation unit.

### Claim 15 (depends on 1)

The CDF according to claim 1, further comprising:
a second capacitor, wherein a first terminal of the second capacitor is coupled to the output terminal of the first SCN, and a second terminal of the second capacitor is coupled to a reference voltage; and
a third capacitor, wherein a first terminal of the third capacitor is coupled to the output terminal of the second SCN, and a second terminal of the third capacitor is coupled to the reference voltage.

### Claim 16 (depends on 15)

The CDF according to claim 15, wherein the second capacitor and the third capacitor are parasitic capacitors.

### Claim 17

A method of a charge domain filter (CDF), comprising:
providing an amplifier, at least one first switch-capacitor network (SCN), at least one second SCN, at least one third SCN and at least one fourth SCN; converting an input signal into a first input signal and a second input signal with the amplifier;
sampling the first input signal with the at least one first SCN;
sampling the second input signal with the at least one second SCN;
summating an output of the first SCN and an output of the fourth SCN, so as to acquire a first summation result;
summating an output of the second SCN and an output of the third SCN, so as to acquire a second summation result;
sampling the first summation result with the at least one third SCN;
sampling the second summation result with the at least one fourth SCN;
setting an impulse response mode of the third SCN through a first mode signal; and
setting an impulse response mode of the fourth SCN through a second mode signal.

### Claim 18 (depends on 17)

The method of the CDF according to claim 17, wherein the amplifier is a transconductance amplifier or an operation amplifier.

### Claim 19 (depends on 17)

The method of the CDF according to claim 17, wherein the impulse response modes of the third SCN and the fourth SCN comprise an infinite impulse response (IIR) mode or a finite impulse response (FIR) mode, and the first SCN and the second SCN support a FIR filter or an IIR filter.

### Claim 20 (depends on 19)

The method of the CDF according to claim 19, wherein in the FIR mode, the third SCN and the fourth SCN provide required frequency responses to equalize the amplitude at a specific frequency.

### Claim 21 (depends on 19)

The method of the CDF according to claim 19, wherein the IIR modes of the third SCN and the fourth SCN are enabled to adjust the level of the amplitude.

### Claim 22 (depends on 17)

The method of the CDF according to claim 17, wherein sampling rates of the third SCN and the fourth SCN are made to be different from sampling rates of the first SCN and the second SCN, so as to modulate an equalized frequency of the CDF.

### Claim 23 (depends on 17)

The method of the CDF according to claim 17, wherein sub SCNs inside the first SCN, the second SCN, the third SCN and the fourth SCN perform time-interleaving operations to reduce a folding frequency, filter clock feed-through from the sub SCNs, and mitigate Sine-function distortion.

### Claim 24

A charge domain filter (CDF), comprising:
an input amplifier, comprising a first output terminal and a second output terminal;
at least one first switch-capacitor network (SCN), comprising an input terminal coupled to the first output terminal of the input amplifier;
at least one second SCN, comprising an input terminal coupled to the second output terminal of the input amplifier;
at least one third SCN, comprising an input terminal coupled to an output terminal of the first SCN;
at least one fourth SCN, comprising an input terminal coupled to an output terminal of the second SCN;
a first output amplifier, wherein a first input terminal of the first output amplifier is coupled to an output terminal of the third SCN, a second input terminal of the first output amplifier is coupled to an output terminal of the second SCN, and an output terminal of the first output amplifier is used as a first output terminal of the CDF; and
a second output amplifier, wherein a first input terminal of the second output amplifier is coupled to an output terminal of the fourth SCN, a second input terminal of the second output amplifier is coupled to the output terminal of the first SCN, and an output terminal of the second output amplifier is used as a second output terminal of the CDF.

### Claim 25 (depends on 24)

The CDF according to claim 24, wherein the input amplifier, the first output amplifier and the second output amplifier are a transconductance amplifier or an operation amplifier.

### Claim 26 (depends on 24)

The CDF according to claim 24, wherein sampling rates of the third SCN and the fourth SCN are different from sampling rates of the first SCN and the second SCN to modulate an equalized frequency of the CDF.

### Claim 27 (depends on 24)

The CDF according to claim 24, wherein sub SCNs inside the first SCN, the second SCN, the third SCN and the fourth SCN perform time-interleaving operations to reduce a folding frequency, filter clock feed-through of the sub SCNs, and mitigate Sinc-function distortion.

### Claim 28 (depends on 24)

The CDF according to claim 24, wherein a mode control terminal of the third SCN receives a first mode signal to set an impulse response mode of the third SCN, and a mode control terminal of the fourth SCN receives a second mode signal to set an impulse response mode of the fourth SCN.

### Claim 29 (depends on 28)

The CDF according to claim 28, wherein the impulse response modes of the third SCN and the fourth SCN comprise an infinite impulse response (IIR) mode or a finite impulse response (FIR) mode, and the first SCN and the second SCN support a FIR filter or an IIR filter.

### Claim 30 (depends on 29)

The CDF according to claim 29, wherein in the FIR mode, the third SCN and the fourth SCN provide required frequency responses to equalize the amplitude at a specific frequency.

### Claim 31 (depends on 29)

The CDF according to claim 29, wherein the IIR modes of the third SCN and the fourth SCN are enabled to adjust the level of the amplitude.

### Claim 32 (depends on 28)

The CDF according to claim 28, wherein a network of the first SCN, the second SCN, the third SCN and the fourth SCN comprises:
a plurality of sampling units, wherein sampling terminals of the plurality of sampling units are coupled to the input terminal of the network, and the plurality of sampling units sample the input terminal of the network through different phases, respectively; and
a summation unit, wherein an input terminal of the summation unit is coupled to output terminals of the plurality of sampling units, and the summation unit summates sampling results of the plurality of sampling units.

### Claim 33 (depends on 32)

The CDF according to claim 32, wherein one of the plurality of sampling units comprises:
a sampling switch, comprising a first terminal coupled to the input terminal of the network;
a sampling capacitor, coupled to a second terminal of the sampling switch;
a reset switch, wherein a first terminal of the reset switch is coupled to the sampling capacitor, and a second terminal of the reset switch is coupled to a reference voltage; and
an output switch, wherein a first terminal of the output switch is coupled to the sampling capacitor, and a second terminal of the output switch is coupled to the input terminal of the summation unit.

### Claim 34 (depends on 32)

The CDF according to claim 32, wherein the summation unit comprises:
a summation capacitor, coupled to the output terminals of the plurality of sampling units.

### Claim 35 (depends on 34)

The CDF according to claim 34, wherein the summation unit further comprises:
a first switch, comprising a first terminal coupled to the output terminals of the plurality of sampling units; and
a first capacitance, coupled to a second terminal of the first switch.

### Claim 36 (depends on 34)

The CDF according to claim 34, wherein the summation unit further comprises:
a second switch, comprising a first terminal coupled to the summation capacitor; and
a third switch, wherein a first terminal of the third switch is coupled to a second terminal of the second switch, a second terminal of the third switch is coupled to a reference voltage, and a control terminal of the third switch receives a mode signal.

### Claim 37 (depends on 32)

The CDF according to claim 32, wherein one of the plurality of sampling units comprises:
a sampling switch, comprising a first terminal coupled to the input terminal of the network;
a sampling capacitor, coupled to a second terminal of the sampling switch;
a first switch, comprising a first terminal coupled to the sampling capacitor;
a first capacitance, coupled to a second terminal of the first switch;
a reset switch, comprising a first terminal coupled to the sampling capacitor;
a second switch, wherein a first terminal of the second switch is coupled to a second terminal of the reset switch, a second terminal of the second switch is coupled to a reference voltage, and a control terminal of the second switch receives a mode signal; and
an output switch, wherein a first terminal of the output switch is coupled to the sampling capacitor, and a second terminal of the output switch is coupled to the input terminal of the summation unit.

### Claim 38 (depends on 32)

The CDF according to claim 32, wherein one of the plurality of sampling units comprises:
a first sampling switch, comprising a first terminal coupled to the input terminal of the network;
a first sampling capacitor, coupled to a second terminal of the first sampling switch;
a first reset switch, wherein a first terminal of the first reset switch is coupled to the first sampling capacitor, and a second terminal of the first reset switch is coupled to a reference voltage;
a second sampling switch, comprising a first terminal coupled to the first sampling capacitor;
a second sampling capacitor, coupled to a second terminal of the second sampling switch;
a second reset switch, wherein a first terminal of the second reset switch is coupled to the second sampling capacitor, and a second terminal of the second reset switch is coupled to the reference voltage; and
an output switch, wherein a first terminal of the output switch is coupled to the second sampling capacitor, and a second terminal of the output switch is coupled to the input terminal of the summation unit.

### Claim 39 (depends on 24)

The CDF according to claim 24, further comprising:
a second capacitor, wherein a first terminal of the second capacitor is coupled to the output terminal of the first SCN, and a second terminal of the second capacitor is coupled to a reference voltage; and
a third capacitor, wherein a first terminal of the third capacitor is coupled to the output terminal of the second SCN, and a second terminal of the third capacitor is coupled to the reference voltage.

### Claim 40 (depends on 39)

The CDF according to claim 39, wherein the second capacitor and the third capacitor are a parasitic capacitor.

### Claim 41

A method of a charge domain filter (CDF), comprising:
providing an input amplifier, at least one first switch-capacitor network (SCN), at least one second SCN, at least one third SCN, at least one fourth SCN, a first output amplifier and a second output amplifier;
converting an input signal into a first input signal and a second input signal with the input amplifier;
sampling the first input signal with the at least one first SCN;
sampling the second input signal with the at least one second SCN;
sampling an output of the first SCN with the at least one third SCN;
sampling an output of the second SCN with the at least one fourth SCN;
receiving and amplifying an output of the third SCN and the output of the second SCN with the first output amplifier, so as to provide a first output of the CDF; and
receiving and amplifying an output of the fourth SCN and the output of the first SCN with the second output amplifier, so as to provide a second output of the CDF.

### Claim 42 (depends on 41)

The method of the CDF according to claim 41, wherein the input amplifier, the first output amplifier and the second output amplifier are a transconductance amplifier or an operation amplifier.

### Claim 43 (depends on 41)

The method of the CDF according to claim 41, wherein sampling rates of the third SCN and the fourth SCN are different from sampling rates of the first SCN and the second SCN, so as to modulate an equalize frequency of the CDF.

### Claim 44 (depends on 41)

The method of the CDF according to claim 41, wherein sub SCNs inside the first SCN, the second SCN, the third SCN and the fourth SCN perform time-interleaving operations, so as to reduce a folding frequency, filter clock feed-through from the sub SCNs, and mitigate Sinc-function distortion.

### Claim 45 (depends on 41)

The method of the CDF according to claim 41, wherein a mode control terminal of the third SCN receives a first mode signal to set an impulse response mode of the third SCN, and a mode control terminal of the fourth SCN receives a second mode signal to set an impulse response mode of the fourth SCN.

### Claim 46 (depends on 45)

The method of the CDF according to claim 45, wherein the impulse response modes of the third SCN and the fourth SCN comprise an infinite impulse response (IIR) mode or a finite impulse response (FIR) mode, and the first SCN and the second SCN support a FIR filter or an IIR filter.

### Claim 47 (depends on 46)

The method of the CDF according to claim 46, wherein in the FIR mode, the third SCN and the fourth SCN provide required frequency responses, so as to equalize the amplitude at a specific frequency.

### Claim 48 (depends on 46)

The method of the CDF according to claim 46, wherein the IIR modes of the third SCN and the fourth SCN are enabled to adjust the level of the amplitude.