Proiect CAIF

Podina Andrei Cosmin

Datele de proiectare:

• LPF: Butterworth, fc-3db=160kHz, amin=17dB, H0=0dB, biquad Multiple Feedback;

• PGA: castig intre 3dB-21dB cu pasul de 3dB, structura cu comutator in afara caii de semnal, banda minima de 350kHZ;

• AO: Miller, cu intrare pe tranzistoare NMOS, n013, cu alimentare intre 0 si 2V.

Alegerea tipului de biquad

• Biquad Multiple Feedback de ordinul 2:

Formule biquad ord 2:

)1

3232(11

R

RRRRCa c

322121 RRCCb c

)32132

(3221

12

)(22 RR

RRR

SRRCCS

RR

SHcc

1

20

R

RH

Valori determinate pentru elementele de circuit:

• R1=R2=158kΩ

• R3=627kΩ

• C2=10pF

• C1=1pF

Caracteristica de modul a FTJ de ord 2

Frequency

1.0Hz 10Hz 100Hz 1.0KHz 10KHz 100KHz 1.0MHz 10MHz 100MHz 1.0GHzDB(v(out)/v(in))

-200

-150

-100

-50

-0

(-17.651m)

(319.108K,-12.365)

(158.229K,-3.0000)

• H0 este de -17m (deci aprox 0dB), frecventa la 3dB=158kHz, amin=-12,36 dB, deci rezulta ca nu este de ajuns un biquad de ord 2 si ca urmare trebuie marit ordinul

Biquad Multiple Feedback de ordin 3:

Formule biquad ordin 3:

• H0=R4R2/R0R1

• a1=2piFcR4C3

• a2=2piFcC1(R2+R3+R2R3/R1)

• b2=(2piFc)^2 C1C2R2R3

Valorile determinate pentru elementele de circuit:

• R4=R0=100kΩ

• R1=R2=480kΩ

• R3=258kΩ

• C2=8p

• C1=1p

• C3=10p

Frequency

1.0Hz 10Hz 100Hz 1.0KHz 10KHz 100KHz 1.0MHz 10MHz 100MHzDB(v(out)/v(in))

-200

-150

-100

-50

-0

(323.959K,-18.769)

(157.687K,-3.0000)(-36.546m)

• H0=-36m

• Fc-3dB=158kHz

• Amin=-18dB

• Toate cerintele sunt indeplinite de unde rezulta ca biquadul dorit este unul de ordinul 3.

Determinarea GBW minim

f(kHz) GBW(MHz) fc-3dB fa=-18,223dB

E1[%] E2[%]

1000 1000 158 670 320 281 0 0

900 900 158 668 320 272 0.001 0.002

500 500 158 646 320 189 0.015 0.028

100 100 158 443 319 459 0.14 0.25

50 50 158 137 318 548 0.33 0.54

40 40 157 981 318 088 0.43 0.68

30 30 157 724 317 330 0.59 0.92

29 29 157 687 317 221 0.6 0.95

28 28 157 650 317 112 0.64 0.989

27 27 157 608 316 991 0.669 1.02

26 26 157 563 316 859 0.69 1.06

Proiectarea amplificatorului operational Miller

Specificatii de proiectare GBW 40 MHz

SR 40 V/us

CL 10pF

PM 60

Vod uzual 200mV

Parametri obtinuti

CM 3.33pF

IM6 753.6 uA

PM 65.21

Tabel PSF

PSF dupa calcul PSF dupa ajustare

W/L ID(uA) Vod(mV) W/L ID(uA) Vod(mV)

M1,M2 7.95 66.6 159.23 22 67.3 159

M3,M4 37.21 66.6 200 37.21 67.3 200

M5 20.16 133.2 200 26.15 135 200

M6 421.06 753.5 200 415 755 200

M7 114.08 753.6 200 143 755 200

M8 7.59 50 200 9.6 50 200

Parametrii AO

Specificatii de proiectare

Parametrii obtinuti dupa proiectare

GAIN (dB) 60 85.189

GBW(MHz >28 30.819

PM (grade) 60 62.85

Caracteristica de modul

Frequency

1.0Hz 10Hz 100Hz 1.0KHz 10KHz 100KHz 1.0MHz 10MHz 100MHzdb(v(out)/v(in))

-50

0

50

100

(30.819M,0.000)

(1.0000,85.189)

Caracteristica de faza

Frequency

1.0Hz 10Hz 100Hz 1.0KHz 10KHz 100KHz 1.0MHz 10MHz 100MHzP(v(out)/v(in))+180

0d

45d

90d

135d

180d

(30.614M,62.685)

Schema amplificator

Schema test amplificator

Schema PGA cu comutator in afara caii de semnal

Corespondenta comutator castig

Castig Comutator inchis

3dB 1.41 SW5 & SW2

6dB 2 SW5 & SW3

9dB 2.81 SW5 & SW4

12dB 4 SW6 & SW1

15dB 5.62 SW6 & SW2

18dB 7.94 SW6 & SW3

21dB 11.22 SW6 & SW4

Valori rezistente obtinute dupa proiectare

• R6=75kΩ• R5=125kΩ• R0=95.25kΩ• R1=16.21kΩ• R2=15.54kΩ• R3=13.5kΩ• R4=50kΩ• R7=50kΩ

Verificare PGA

Castig ideal Castig real THD[%] Eroarea relativa

3dB 1.41 3.0136 2.88 0.45%

6dB 2 6.0457 3.59 0.75%

9dB 2.81 8.996 3.81 0.04%

12dB 4 12.066 5.23 0.55%

15dB 5.62 15.048 3.16 0.32%

18dB 7.94 18.080 3.2 0.44%

21dB 11.22 21.030 3.65 0.14%

Rezultate analiza domeniu timp:1.castig 3dB

Time

0s 4us 8us 12us 16us 20us 24us 28usV(out) V(in)

0V

0.5V

1.0V

1.5V

2.0V

2.Castig 6 dB

Time

0s 4us 8us 12us 16us 20us 24us 28usV(out) v(in)

0V

0.5V

1.0V

1.5V

2.0V

3.Castig 9 dB

Time

0s 4us 8us 12us 16us 20us 24us 28usv(out) v(in)

0V

0.5V

1.0V

1.5V

2.0V

4.Castig 12 dB

Time

0s 4us 8us 12us 16us 20us 24us 28usv(out) v(in)

0V

0.5V

1.0V

1.5V

2.0V

Verificare LPF+PGA1.castig 3dBTHD=5.31

Time

0s 1us 2us 3us 4us 5us 6us 7us 8us 9us 10usv(out)

0.8V

1.0V

1.2V

1.4V

Castig=6dBTHD=5.52

Time

0s 1us 2us 3us 4us 5us 6us 7us 8us 9us 10usv(out)

0.8V

1.0V

1.2V

1.4V

Castig=9dBTHD=5.42

Time

0s 1us 2us 3us 4us 5us 6us 7us 8us 9us 10usv(out)

0.8V

1.0V

1.2V

1.4V

Castig=12dBTHD=5.26

Time

0s 1us 2us 3us 4us 5us 6us 7us 8us 9us 10usv(out)

0.9V

1.0V

1.1V

1.2V