CN106923818A - For the ECG signal sampling chip of wearable device - Google Patents

Abstract

The present invention provides a kind of ECG signal sampling chip for wearable device, including：Preamplifier receives the electrocardiosignal of the double-width grinding of ECG detecting electrode collection, generation one-level is amplified to electrocardiosignal and amplifies signal, and one-level is amplified into signal transmission to post-amplifier；One-level amplification signal is converted to single-ended signal by post-amplifier, two grades of amplification signals of generation is amplified to single-ended signal, and amplify signal transmission to RC high-pass filters by two grades；RC high-pass filters amplify signals to two grades carries out high-pass filtering treatment, two grades of amplification signals of generation high pass, and by high pass two grades amplify signal transmissions to second order Gm-C low pass filters；Second order Gm-C low pass filters carry out low-pass filtering treatment to two grades of amplification signals of high pass, generate bandpass filtered signal, and bandpass filtered signal is transmitted to buffer, carry out buffer and export；Power management module is used to provide supply voltage and reference voltage.

Description

For the ECG signal sampling chip of wearable device

Technical field

The present invention is on a kind of ECG signal sampling technology, specifically on a kind of heart for wearable device Electrical signal detection chip.

Background technology

Electrocardiogram (ECG) records heart electrical potential activity, for the research and diagnosis of angiocardiopathy provide the information of key. In early stage cardiac disease monitoring, an electrocardiogram is difficult to capture effective diagnosis basis, and Holter (DCG) can 24 hours overall processes of electrocardio-activity are continuously recorded, it can be found that the ND rhythm of the heart of an electrocardiogram of routine loses The important objective basis that the symptoms such as normal and myocardial ischemia are the clinical analysis state of an illness, establish diagnosis, judge curative effect, DCG Can realize that the health status of long-term real-time monitoring patient being capable of real-time detection for a long time.Traditional ECG testing equipments (12 Lead or Einthoven's triangle) require that patient has to carry out real-time monitoring in hospital for a long time, to patient Daily life make troubles, and increase medical treatment cost.

Wearable Medical Devices allow patient to proceed through the personalized health management of scientific design in daily life, keep away Exempt to see emergency treatment and hospitalization, medical treatment number of times is reduced, so as to expense and human cost can be reduced.As people are to itself The attention rate of health is improved, and wearable Medical Devices have more extensive Demand Base, and health medical treatment equipment will turn into Necessary consumer goods.Core sensor technology, low-power consumption process chip and rear end in domestic wearable device are accurately given birth to Reason signal analysis method also has larger gap compared with developed countries.ECG acquisition chips mainly collect in the market In company abroad, such as TI, ADI and Neurosky, but too high power consumption (supply voltage>2V, supply electricity Stream>100uA) for the application of wearable device it is the key issue being badly in need of solving, and big electronic component (electric capacity, Resistance) excessive chip area can be consumed.Though country's report has a kind of fully integrated commercialization single channel ECG collection cores Piece, but the chip exorbitant expenditure power consumption (150uA), low pass filter in circuit structure uses traditional Gm-C Structure is, it is necessary to big filter capacitor, takes excessive chip area, and input impedance (100M Ω) cannot meet dry The use requirement of electrode.

The content of the invention

The main purpose of the embodiment of the present invention is to provide a kind of ECG signal sampling chip for wearable device, with While realizing that low-power consumption, low noise work, chip area is reduced.

To achieve these goals, the embodiment of the present invention provides a kind of ECG signal sampling chip for wearable device, Described ECG signal sampling chip includes：Preamplifier, post-amplifier, RC high-pass filters, second order Gm-C Low pass filter, buffer and power management module, wherein, the preamplifier receives the collection of ECG detecting electrode Double-width grinding electrocardiosignal, generation one-level is amplified to the electrocardiosignal and amplifies signal, and by the one-level Amplify signal transmission to described post-amplifier；The post-amplifier is converted to one-level amplification signal single-ended Signal, two grades of amplification signals of generation is amplified to the single-ended signal, and amplify signal transmission to institute by described two grades The RC high-pass filters stated；The RC high-pass filters amplify signal to described two grades carries out high-pass filtering treatment, Generation two grades of high pass amplification signals, and by the high pass two grades amplify signal transmissions to the second order Gm-C LPFs Device；The second order Gm-C low pass filters carry out low-pass filtering treatment to two grades of amplification signals of the high pass, generate band Bandpass filtered signal, and the bandpass filtered signal is transmitted to described buffer, buffer is carried out, and export institute State bandpass filtered signal；The power management module is high with described preamplifier, post-amplifier, RC respectively The link of bandpass filter, second order Gm-C low pass filters and buffer, is used to provide supply voltage and reference voltage.

In one embodiment, above-mentioned ECG signal sampling chip also includes：Driven-right-leg circuit module, the right leg Drive circuit module is connected between the ECG detecting electrode and preamplifier, is used to detect the electrocardiosignal Common-mode voltage simultaneously feeds back to human body, to reduce the interference of work mould.

In one embodiment, above-mentioned ECG signal sampling chip also includes：Lead-fail detector detection module, the lead The detection module that comes off is connected between the ECG detecting electrode and preamplifier, is used to detect the connection status of lead.

Further, above-mentioned lead-fail detector detection module includes：Resistance, PMOS and comparator, wherein, two The individual comparator is made up of two-stage amplifier respectively, what each comparator respectively gathered the ECG detecting electrode Electrocardiosignal is compared with a reference voltage, when it is high level to export logic, judges the connection of the lead not Normally.

In one embodiment, above-mentioned preamplifier is fully differential structure, and the preamplifier amplifies including instrument Device, electric capacity and PMOS puppet resistance, the instrument amplifier use phase inverter input structure, be used to strengthen mutual conductance, Reduce input noise；The instrument amplifier and four electric capacity composition capacitance ratio amplifying circuits, and be connected across On the instrument amplifier the PMOS puppet resistance constitute high-pass filtering structure, be used to carry out cut-off frequency be f_h=1/2 π RC₂High-pass filtering；Wherein, R is PMOS puppet resistance, C₂It is the electric capacity.

In one embodiment, the transmission function of above-mentioned preamplifier is：A_V=RC₁s/(1+C₂S), wherein, C₁=C₂。

In one embodiment, above-mentioned second order Gm-C low pass filters are used using electric current transmission structure CCII is based on It is to carry out cut-off frequency) LPF, the biography of the second order Gm-C low pass filters Delivery function is：Wherein, r_ccIt is parallel equivalent resistance, R_oIt is equivalent output impedance, α is The tracking error factor, β is current gain.

The beneficial effect of the embodiment of the present invention is that may be such that power consumption noise is improved, and can realize increasing high Benefit, and effectively reduce silicon area.

Brief description of the drawings

In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, embodiment will be described below Needed for the accompanying drawing to be used be briefly described, it should be apparent that, drawings in the following description are only of the invention Some embodiments, for those of ordinary skill in the art, without having to pay creative labor, may be used also Other accompanying drawings are obtained with according to these accompanying drawings.

Fig. 1 is the structural representation of the ECG signal sampling chip for wearable device according to the embodiment of the present invention；

Fig. 2 is that the structure of the ECG signal sampling chip for wearable device according to another embodiment of the present invention is shown It is intended to；

Fig. 3 is the electrical block diagram of the driven-right-leg circuit module according to the embodiment of the present invention；

Fig. 4 is the circuit principle structure schematic diagram of the lead-fail detector detection module according to the embodiment of the present invention；

Fig. 5 A and Fig. 5 B are the structural representation of the instrument amplifier according to the embodiment of the present invention；

Fig. 5 C are the circuit principle structure schematic diagram of the preamplifier according to the embodiment of the present invention；

Fig. 6 A and Fig. 6 B are the circuit principle structure schematic diagram of the post-amplifier according to the embodiment of the present invention；

Fig. 7 A and Fig. 7 B are the circuit principle structure schematic diagram of the Gm-C low pass filters according to the embodiment of the present invention；

Fig. 8 is the domain of the ECG signal sampling chip according to the embodiment of the present invention；

Fig. 9 is the gain versus frequency response Bode diagram of the ECG signal sampling chip according to the embodiment of the present invention；

Figure 10 is the circuit signal transient analysis result schematic diagram of the ECG signal sampling chip according to the embodiment of the present invention；

Figure 11 is the pass of the input reference noise density with frequency of the ECG signal sampling chip according to the embodiment of the present invention It is schematic diagram；

Figure 12 is the relation schematic diagram of the input impedance with frequency of the ECG signal sampling chip according to the embodiment of the present invention.

Specific embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments. Based on the embodiment in the present invention, what those of ordinary skill in the art were obtained under the premise of creative work is not made Every other embodiment, belongs to the scope of protection of the invention.

The embodiment of the present invention provides a kind of ECG signal sampling chip for wearable device.Below in conjunction with accompanying drawing to this Invention is described in detail.

The embodiment of the present invention provides a kind of ECG signal sampling chip for wearable device, as shown in figure 1, the heart Electrical signal detection chip mainly includes：Preamplifier 1, post-amplifier 2, RC high-pass filters 3, second order Gm-C low pass filters 4, buffer 5 and power management module 6 etc..

Wherein, preamplifier 1 receives the electrocardiosignal of the double-width grinding of ECG detecting electrode collection, to electrocardiosignal It is amplified generation one-level and amplifies signal, and one-level is amplified into signal transmission to post-amplifier 2；Post-amplifier 2 One-level amplification signal is converted into single-ended signal, two grades of amplification signals of generation are amplified to single-ended signal, and by two grades Amplify signal transmission to RC high-pass filters 3；Two grades of RC high-pass filters 3 pair amplify signal carries out high-pass filtering Treatment, generation two grades of high pass amplification signals, and by high pass two grades amplify signal transmissions to second order Gm-C low pass filters 4；Second order Gm-C low pass filters 4 carry out low-pass filtering treatment to two grades of amplification signals of high pass, generate bandpass filtering Signal, and bandpass filtered signal is transmitted to buffer 5, buffer is carried out, and export bandpass filtered signal；Electricity Source control module 6 is low with preamplifier 1, post-amplifier 2, RC high-pass filters 3, second order Gm-C respectively Bandpass filter 4 and buffer 5 are linked, and are used to provide supply voltage and reference voltage.

Power frequency is the main common mode disturbances of electrocardiosignal, and input only can not be completely eliminated by common-mode rejection ratio amplifier high The common-mode noise at end, therefore, as shown in Fig. 2 in embodiments of the present invention, the above-mentioned heart for wearable device Electrical signal detection chip may also include a driven-right-leg circuit module 7, and the driven-right-leg circuit module 7 is connected to electrocardio Between detecting electrode and preamplifier 1, it is used to the detection electrocardio letter collected to input buffer 5 (Buffer) Number common-mode voltage and feed back to human body, with reduce work mould interference.Specifically, the electricity of the driven-right-leg circuit module 7 Line structure is as shown in Figure 3.

Further, the ECG signal sampling chip for wearable device of the embodiment of the present invention may also include a lead Come off (the LMC of detection module 8:Lead-off monitor) monitoring lead connection status, alarm is sent when malunion is normal. The lead-fail detector detection module 8 is connected between ECG detecting electrode and preamplifier 1, is used to detect the company of lead Connect state.Specifically, its circuit principle structure is as shown in figure 4, big resistance (resistance is hundreds of megohms of resistance) Series connection PMOS and comparator constitute lead-fail detector detection module 8, wherein, comparator is by simple two grades amplifications Device composition, the electrocardio input signal for respectively gathering two ECG detecting electrodes and the reference voltage with offer outside chip VREF is compared, if output logic is high level, then it represents that lead malunion is normal.

Above-mentioned preamplifier 1 is fully differential structure, as shown in Figure 5A, instrument amplifier (IA:instrucmental Amplifier) using phase inverter input structure (M_p1, M_n1, M_p1And M_p2), mutual conductance being enhanced, can be effectively reduced Input noise, source degeneration structure (M_n3And M_n4) common-mode feedback structure enhance common-mode rejection ratio.Implement one In example, above-mentioned instrument amplifier also can be using the two-layer configuration of standard as shown in Figure 5 B.As shown in Figure 5 C, High-pass filtering structure in preamplifier 1 is by electric capacity C₁、C₂、C_fAnd PMOS puppet resistance compositions, it is whole preposition The circuit structure of amplifier 1 has symmetrical structure, electric capacity C_fThe positive feedback loop of composition improves input impedance.

Electrocardiosignal is small-signal of tens microvolts (μ V) to hundreds of microvolts (μ V) level, and load capacity is poor, human body Resistance is the big resistance of kilo-ohm (k Ω) to megaohm (M Ω) level, it is therefore desirable to the equivalent inpnt resistance for gathering front end is enough Greatly, the principle of partial pressure of otherwise being connected according to circuitous resistance, it is difficult to ensure the electrocardiosignal intensity collected from human body.This Invention introduces electric capacity positive feedback in preamplifier 1, can significantly improve circuit equivalent input resistance.

Shown in the transmission function of above-mentioned preamplifier 1 such as formula (1)：

A_V=RC₁s/(1+RC₂S), (1)

Wherein, s is the complex variable in transmission function, and R is the equivalent resistance of PMOS puppet resistance, C₁And C₂For upper State the capacitance of electric capacity, C₁=C₂。

Instrument amplifier (IA) constitutes capacitance ratio amplifying circuit with four electric capacity, realizes the enlarging function of gain, while Realize that cut-off frequency is f jointly with the virtual resistance being connected across on instrument amplifier_h=1/2 π RC₂High-pass filtering Characteristic.

The one-level exported by the both-end of preamplifier 1 amplifies what signal was constituted via programmable amplifier and electric capacity again Double-end-to-singlecircuit circuit (i.e. post-amplifier 2), exports the single-ended signal after two grades of amplifications and is filtered to above-mentioned RC high passes Wave circuit, as shown in Fig. 6 A and Fig. 6 B.One-level amplification signal is being changed into the same of single-ended signal by post-amplifier 2 When play the amplification (A of gain_V=C₃/C₄).By the switch being connected across in the branch road at programmable amplifier two ends The ratio of electric capacity is adjusted, the gain controllable of whole ECG chips can be made.

Two grades after above-mentioned preamplifier 1 and post-amplifier 2 amplify are amplified single-ended signal and enter filtered electrical Road is filtered.Above-mentioned RC high-pass filtering circuits are first passed around, high-pass filtering is carried out, then, by above-mentioned Second order Gm-C low pass filters 4 carry out LPF.Fig. 7 A are Low-Pass Second Order Filter structure, are based on by two The single order Gm-C low pass filters of electric current transfer structure (CCII) are constituted, amplifier architecture (Fig. 7 B institutes in wave filter Show) two output ends (Vo1 and Vo2) are designed as, an output end constitutes the negative-feedback of amplifier, realizes effective electricity Hold (Cs) to multiply again, increase equivalent capacitance；Another output end realizes output impedance high as main output.Its Shown in transmission function such as formula (2)：

Wherein, C_sIt is load capacitance, r_ccIt is parallel equivalent resistance, R_oEquivalent output impedance, α be tracking error because Sub (tracking error factor ≈ 1), β is current gain.Can realize cutting by second order Gm-C low pass filters 4 Only frequencyLPF.Thus, two grades of amplification single-ended signals can be entered by filter circuit Row filtering generation frequency is f_h~f bandpass filtered signals.In one embodiment, the cut-off of above-mentioned RC high-pass filters 3 Frequency is 0.5Hz, and it is 5pF that second-order filter electric capacity has altogether in second order Gm-C low pass filters 4, is capable of achieving cut-off Frequency is the LPF of 150Hz, then the bandpass filtered signal by being generated after second order Gm-C low pass filters 4 Frequency be 0.5Hz~150Hz, but frequency values described herein are merely illustrative of, and are not used to limit the present invention.

Wave filter of the invention (generally needs several compared with the traditional second order filter used in common ECG circuit Ten pF), the second order Gm-C low pass filters 4 of the embodiment of the present invention have effectively saved silicon area.Also, it is logical Cross selection load capacitance Cs, it is possible to achieve the bandwidth frequency of chip is controllable.

Above-mentioned power management module 6 includes reference voltage stabilizing source (bandgap voltage reference) low voltage difference (LDO: Low drop-out) linear voltage regulator, unity gain buffer (buffer), bias current circuit, so as to be whole electricity Road provides the supply voltage and offset operation electric current of stabilization.

Based on above-mentioned each part, the ECG signal sampling chip master for wearable device of the embodiment of the present invention There is advantages below：

(1) input structure of phase inverter ensure that the operation of preamplifier low-power consumption low noise；

(2) input stage of positive feedback loop increased input impedance；

(3) two Jie's filter structures based on electric current transfer structure realize low cut-off frequency.Irrigated hereby with traditional Bart Second order Gm-C wave filters are compared, it is to avoid used big electric capacity, effectively saved silicon area；

(4) whole ECG acquisition chips consume the electric current of 70uA, and supply voltage is 1.2V.

In specific implementation, to the ECG signal sampling chip for wearable device of the embodiment of the present invention in smic It is designed and emulates under CMOS0.18-um techniques, Fig. 8 is illustrated that the domain of the ECG signal sampling chip, The area of whole circuit is about 0.35mm².Supply voltage is 1.2V, preamplifier circuit consumption about 400nA's Electric current, whole ECG acquisition chips consume the electric current of about 70uA.Fig. 9 shows the gain versus frequency response baud of circuit Figure, the gain of preamplifier is 83dB, and band logical frequency is 0.5Hz~150Hz.Input and the transient response of output It is simulated, as shown in Figure 10, when input signal amplitude is 20uV, amplitude output signal is about 20mV.Figure The 11 input reference noise density for showing instrument amplifier, input noise is 2.42uV in 0.5~150Hz of frequency range.Figure 12 input impedance for showing emulation, it can be seen that positive feedback loop causes that input impedance is significantly improved, and is about in 80Hz 2.4GΩ.Table 1 show the ECG signal sampling chip and prior art for wearable device of the embodiment of the present invention The comparative result of middle ECG acquisition chips.

Table 1

	The present invention	Previous work [1]
			Manufacturing process	SMIC 0.18um	SMIC 0.18um
Port number	Single channel	Single channel
			Supply voltage	1.2V	2.7-5V
Static current of lcd	70uA	150uA
			Input reference noise	2.42uV	＜ 10uV
Input impedance	2.4GΩ	100MΩ
			Gain	40dB*/83dB	51dB
Common-mode rejection ratio	96dB*	90dB
			PSRR	80dB*(110dB)	90dB
Bandwidth	0.5~150Hz	0.7~120Hz
			Area	0.35mm2	0.5mm2

*:Preamplifier ():Including power circuit

It can be seen from Table 1 that, the ECG signal sampling chip for wearable device of the embodiment of the present invention causes work( Consumption noise is improved, and can realize high-gain, and effectively reduces silicon area.

Particular embodiments described above, has been carried out further in detail to the purpose of the present invention, technical scheme and beneficial effect Describe in detail bright, should be understood that and the foregoing is only specific embodiment of the invention, be not used to limit this hair Bright protection domain, all any modification, equivalent substitution and improvements within the spirit and principles in the present invention, done etc., Should be included within the scope of the present invention.

Claims (7)

1. a kind of ECG signal sampling chip for wearable device, it is characterised in that described electrocardiosignal inspection Surveying chip includes：Preamplifier, post-amplifier, RC high-pass filters, second order Gm-C low pass filters, Buffer and power management module, wherein,

The preamplifier receives the electrocardiosignal of the double-width grinding of ECG detecting electrode collection, to the electrocardiosignal It is amplified generation one-level and amplifies signal, and the one-level is amplified into signal transmission to described post-amplifier；

One-level amplification signal is converted to single-ended signal by the post-amplifier, and the single-ended signal is amplified Two grades of amplification signals of generation, and amplify signal transmission to described RC high-pass filters by described two grades；

The RC high-pass filters amplify signal to described two grades carries out high-pass filtering treatment, the two grades of amplifications of generation high pass Signal, and two grades of the high pass is amplified into signal transmissions to the second order Gm-C low pass filters；

The second order Gm-C low pass filters carry out low-pass filtering treatment to two grades of amplification signals of the high pass, generate band Bandpass filtered signal, and the bandpass filtered signal is transmitted to described buffer, buffer is carried out, and export institute State bandpass filtered signal；

The power management module respectively with described preamplifier, post-amplifier, RC high-pass filters, two Rank Gm-C low pass filters and buffer are linked, and are used to provide supply voltage and reference voltage.

2. the ECG signal sampling chip for wearable device according to claim 1, it is characterised in that Described ECG signal sampling chip also includes：

Driven-right-leg circuit module, the driven-right-leg circuit module is connected to the ECG detecting electrode and preposition amplification Between device, it is used to detect the common-mode voltage of the electrocardiosignal and feeds back to human body, reduces the interference of work mould.

3. the ECG signal sampling chip for wearable device according to claim 1, it is characterised in that Described ECG signal sampling chip also includes：

Lead-fail detector detection module, the lead-fail detector detection module is connected to the ECG detecting electrode and preposition amplification Between device, it is used to detect the connection status of lead.

4. the ECG signal sampling chip for wearable device according to claim 3, it is characterised in that The lead-fail detector detection module includes：Resistance, PMOS and comparator, wherein,

Two comparators are made up of two-stage amplifier respectively, and each comparator is respectively by the ECG detecting electrode The electrocardiosignal of collection is compared with a reference voltage, when it is high level to export logic, judges the company of the lead Connect abnormal.

5. the ECG signal sampling chip for wearable device according to claim 1, it is characterised in that The preamplifier is fully differential structure, and the preamplifier includes that instrument amplifier, electric capacity and PMOS are pseudo- Resistance,

The instrument amplifier uses phase inverter input structure, is used to strengthen mutual conductance, reduces input noise；

The instrument amplifier and four electric capacity composition capacitance ratio amplifying circuits, and put with the instrument is connected across PMOS puppet resistance on big device constitutes high-pass filtering structure, is used to carry out cut-off frequency for f_h=1/2 π RC₂'s High-pass filtering；Wherein, R is PMOS puppet resistance, C₂It is the electric capacity.

6. the ECG signal sampling chip for wearable device according to claim 5, it is characterised in that The transmission function of the preamplifier is：

A_V=RC₁s/(1+RC₂S), wherein, s be transmission function in complex variable, C₁=C₂。

7. the ECG signal sampling chip for wearable device according to claim 1, it is characterised in that The second order Gm-C low pass filters using be based on electric current transmission structure CCII, be used to carry out cut-off frequency beLPF, the transmission function of the second order Gm-C low pass filters is：

$\frac{V_{out}}{V_{in}}=\frac{r_{cc}^2}{{(r_{cc}+R_o+{\mathrm{s\α\βC}}_s)}^2},$

Wherein, C_sIt is load capacitance, r_ccIt is parallel equivalent resistance, R_oIt is equivalent output impedance, α is tracking error The factor, β is current gain.