Telescopic OP AMP Design
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Transcript of Telescopic OP AMP Design
Telescopic OP-AMPClick to edit Master subtitle style
Group MembersSami ur Rehman Adeel Ahmed Khan Kahif Raheem
7/26/12
Circuit DiagramC M M O b 2 S P C M M 7 O S P C M M 8 O S P V 2 9 2 . 5 V d c I r e f 2 1 0 0 u A d c M 4VDB
C M
M 5
O
S
P
C M
M 6
O
S
P
0
0
M
3
M 1 0 0 u A I r e f 1 d c V 3 1 0 . 0 1 V a c 0 V d c M b 1
1
M
2
M
9
1 . 1
V 7 V
3 2 d c
0V 1 . 1 7 V 3 0 d c
0 0
0 7/26/12
Design ParametersVariables UGBW DC Gain Capacitive Load ITOTAL Differential Output Swing Vin,CM VDD n, p n, p7/26/12
Value >50MHz >40dB < 2pF 2V 1-1.4 V 2.5 V 60 A / v2 0.05 V-1
Step 1: Allocation of Currents
Total Circuit Power Dissipation
Pd = ITOTAL x VDD = 0.25 mW
Allocating
Currents below: IM9 = 80 A IMb1 & Mb2 = 10 A
Each
cascode branch has a divided current of 40 A7/26/12
CurrentsC M M O b 2 S P C M M 7 O S P C M M 8 O 2 S . 5 P V V d 2 9 c I r e 1 0 0 u A d c f 2 C M M 5 O S P C M M 6 O S P
0
0
40 Af 1 V 3 1 0 . 0 1 V a c 0 V d c
M
3
M
4VDB
40 A
M 1 0 0 u A I r e d c
1
M
2
M
b 1
M
9 1 . 1 7
V V
3 2 d c
0V 1 . 1 7 V 3 d 0 c
0 0
5A
7/26/12 0
80A
Step 2: Allocation of VoltagesGiven
swing is greater than 2V Lets say single ended swing required is 1.2V Power Supply voltages are 2.5 v
2.5 v 1.2 v = 1.3 v
Over
drive voltages in one side cascode regions: VOD7 + VOD5 +VOD3 + VOD1 + VOD9 = 1.3 v Allocating, M9 transistor voltages 7/26/12
VoltagesVOD7 + VOD5 + VOD3 + VOD1 + VOD9 = 1.3 V VOD5 = VOD7 VOD1 + = 0.5v VOD3 = 0.4 v 0.4 V
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VoltagesC M M O b 2 S P C M M 7 O S P C M M 8 O S P V 2 9 2 . 5 V d c I r e f 2 1 0 0 u A d c M 4VDB
C M
M 5
O
S
P
C M
M 6
O
S
P
0
VOD5 to VOD8 0.5 v VOD1 to VOD3 = 0.4v VOD9 = 0.4 v
0
M
3
1 0
0 u A
I r e f 1 d c
90 AV 3 1 0 . 0 1 V a c 0 V d c
M
1
M
2
M
b
1
M
9
1 . 1
V 7 V
3 2 d c
0V 1 . 1 7 V 3 0 d c
0 0
0
7/26/12
Stye 3: Calculating W/L RatioTo
calculate W/L ratio, we use Level 1 saturation equation of MOSFET transistorwhere ID = K = Cox
Re-arranging Equation
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W/L RatioTransistor
M9 M1-4 M5-8
W/L = 8.66 W/L = 16.67 W/L = 10.67
Transistor
Transistor
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W/L RatioC M M O S b 2 P C M I r e f 2 1 0 0 u A d c C M
W/L5-8 = 10.67M 7 O S P C M M 8 O S P V 2 9 2 . 5 V d c
M 5
O
S
P
C M
M 6
O
S
P
0
0
M
3
M
4VDB
M 1 0 0 u A I r e f 1 d c V 3 1 0 . 0 1 V a c 0 V d c M b 1
1
W/L1-4 = 16.67M 9
M
2
0V 1 . 1 7 V 3 0 d c
W/L9 = 8.66
1 . 1
V 7 V
3 2 d c
0 0
0 7/26/12
Step 4: Calculating GainAv = (gm1 + gm3 ro3 ro1)// ( gm5 ro5 ro7)
Where gm can be found by
2I D gm = VOV
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Parameter gm1 gm3 ro3 ro1 gm5 ro5 ro7
Resulting values of Parameters
Value 4 e -4 4 e -4 500,000 500,000 2 e -4 500,000 500,000
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DC Gain (V/V) DC Gain (dB)Av = 13,333 v/v> 40
Av (dB) = 82.5 dB
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Unity Gain BandwidthVin Two Port Circuit Vout 2pf
Where R = Rout of the circuit
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7/26/12
Unity Gain BandwidthUGBW = g m1,2 CL
4 1 04 U G B W= 2 6 6 .6 7 = 12 1 .5 1 0
MHz
7/26/12