• Measured parasitic resistance and capacitance of two cascoded NMOS layout in LNA. Reduced down the parasitic resistance to about 1 ohm using a multi-fingered and multi-contacted layout. • Analyzed the Q-based tuning of RFIC LNA by adding an ideal capacitor between the gate and source of CS stage of cascoded LNA and the corresponding variation of linearity using Cadence SpectreRF simulations.

1. THE UNIVERSITY OF TEXAS AT DALLAS
ERIK JONSSON SCHOOL OF ENGINEERING & COMPUTER SCIENCE
EERF 6330 RFIC DESIGN Kenneth O.
SPRING 2016
PARASITICS REDUCTION FOR RFIC CMOS LAYOUT AND IIP3 VS Q-BASED
DESIGN ANALYSIS USING IBM 130NM TECHNOLOGY
BY ILANGO JEYASUBRAMANIAN (ixj150230)

2. LAYOUTFOR CASCODESTAGEOF TWO NMOS IN LNA:
PARASITIC RESISTANCECALCULATION:
Rpoly= 7 ohm/sq, RM1 =0.0709 ohm/sq , RM2,3 =0.0639 ohm/sq
Width of each NMOS = WNFET = 40um
Number of fingers = NF = 40
Width of each finger = WF = 1um
Length of each finger = LF = 0.12um
Widths of gate around the contact : WPCONT = 0.2um, Wp = 0.4um
Width of external gate between transistor and contact = Wext = 0.08um
Lp = 18.84um
Npcont = Lp/Wp = 47
Wcont = 0.16um
Rgp =
1
𝑁 𝑓
[
𝑊 𝑓𝑖𝑛𝑔𝑒𝑟
12∗𝐿
𝑅 𝑝𝑜𝑙𝑦 +
𝑊 𝑓𝑖𝑛𝑔𝑒𝑟
2∗𝐿
𝑅 𝑝𝑜𝑙𝑦 + (
𝑊 𝑓𝑖𝑛𝑔𝑒𝑟
𝑊 𝑝
+ 0.5)
𝑅 𝑝𝑜𝑙𝑦
2
]
Rgp =
1
40
[
1𝑢𝑚
12∗0.13𝑢𝑚
7 +
0.08
2∗0.12𝑢𝑚
7 + (
0.2
0.4
+ 0.5)
7
2
]

3. Rgp =0.2ohm
Rg,cont =
𝑅 𝑐𝑜𝑛𝑡
𝑁 𝑐𝑜𝑛𝑡
= 8/47 = 0.19ohm
Rg = Rgp +
𝑅 𝑔,𝑐𝑜𝑛𝑡
2
=0.2 + (0.19/2) =0.3ohm
METAL_GATE RESISTANCES:
Lm 1,1 = 21.06um, Lm 1,2 = 0.78um, Lm 1,3 = 0.4um, Lm1 = 0.4um, Lm 1,s = 0.4um
R1 =
Lm 1,1−2 Lm1
3𝐿𝑚1
. Rm1 = ((21.06-2(0.5))/(3*0.5))*0.0709 =0.948ohm
R2 =
Lm 1,2−2 Lm1
𝐿𝑚1
. Rm1 = ((1.38-0.5)/0.5)*0.0709=0.25ohm
R3 =
Lm 1,3
𝐿𝑚1
. Rm1 = (0.4/0.4)*0.0709=0.0709ohm
Rc1 = Rc2 = 0.035ohm
Rmetal, g =(1/2)[R1 +2R2 +Rc1+Rc2} + R3 =(1/2)[0.948+0.125*2+0.035+0.035] +0.0709
= 0.7ohm
Rvia1 =Rvia2 = 0.9/60 = 0.015ohm
RTOTAL = Rg,POLY +Rg,metal +Rvia1 +Rvia2 = 0.3+0.7+0.015+0.015 =0.998ohm
The parasitic resistance is reducedtoabout 1ohm by using multi-fingeredlayout andincreasing
the number of parallel connections.
Lm1
R1
Rc1
Lm1,2
R2
Rc2
Lm1,s
Lm1,3
R3
Lm1,1

4. PARASITIC CAPACITANCECALCULATION:
W = 80 um;
𝜑 𝑏 = 0.7341 , 𝜑 𝑏𝑠𝑤 = 0.6662, 𝜑 𝑏𝑠𝑤𝑔 = 1.40 ,
Cj = 0.00105, Cjsw =1.1*10^(-10), Cjswg =3.5*10^(-10),
Mj =0.3647, Mjsw = 1.052, Mjswg =0.732
Cgbo=17.06p; Cgdl=330p; Cgsl=330p; dlc=34.47n
Cox=3.9*8.85*10E-12/3.12*E-9=0.011
Cgso=Cox*dlc-Cgsl=Cox*34.47*E-9-3.3*E-10= 5.13E-11 F/m
Cgs=2/3CoxW*(L-2Lov)+Cgso*w=2/3*Cox*80E-6*(0.12E-6-2*1.4E-8)+ Cgso*80E-6 + NfCgb0L=
58f+4.104f+0.0818f=62.2fF
Cgdo=Cox*dlc-Cgdl= Cox*34.47E-9-3.3E-10= Cgso = 5.13E-11 F/m
Cgbo=2*dwc*Cox=3.76E-11F/m
Cgd = CgdoW = -5.13E-11 x80E-6=4.104fF
Cin = Cgs+2Cgd = 70.408fF
Cdb=Area*Cjo*(1-Vbd/ φb) mj+Perimeter* Cjswo*(1-Vbd/ φbsw)mjsw
Cdb=25*6E-6*0.36E-6*1E-4*(1+1.093/0.6)^0.5+(2*6+0.36*25)E-6*2E-10*(1+1.093/0.6)^0.5=63.44Ff
ANALYSIS OF TUNING IN AN INPUT MATCHED LNA BYUSING Cgs IN COMMON STAGE OF LNA:
Since in a cascaded LNA,CT = 1/(2wZoQin) = Cgs + (1+(gm1/gm2))Cgd .The resonant frequency
can be increased or decreased by decreasing or adding the additional Cgs capacitor across the CS stage.However, we can also see that Qin
increases or decreases as CT decreases or increases correspondingly. It also affects the linearity, which is being simulated and analyzed from
IIP3 simulation shown below:
(a): Given:
Qin = 2; Vds1 = 0.3V
To get Id = 2mA,
W = (Id * L) / ( Un.Cox * Vds2
) = ((2*10-3
)* (120*10-9
) / ( 147.1*10-6
* 0.32
) = 18um
For input matching:
Lg = (2 * Zo * Qin) / w = (2*50*2) / (2*3.14*2.4*(109)) = 13.269nH
Ls = Zo / (gm*Qin*(2*Zo*w)) = Ls = (50)/(10*10-3*2*2*50*2*3.14*2.4*109) = 1.6587nH
CT = 1/(w*(2*Zo)*Qin) = 1/(2*50*2*3.14*2.4*109 *2) = 0.33174pF
Cin = Cgs+ 2Cgd = 16.66fF + (2*5.636) = 0.33174pF
Additional Cgs = CT – Cin = 0.30474pF

5. SCHEMATIC:
IIP3_SIMULATION:
For Qin =2, IIP3 = -1.94dbm

6. (b) For Qin =1.5:
Additional Cgs = CT – Cin = 0.4153pF
For Qin =1.5, IIP3 = 0.39dbm
For Qin =0.5:
Additional Cgs = CT – Cin = 1.3pF
For Qin =0.5, IIP3 = 13.59dbm

7. (c): IIP3(mW) vs Qin:
We know that IIP3 =( 8*(Vgs – Vt))/(4*Qin
2 *Zo*3𝜽) which causes the IIP3 increases as Qin decreases. Hence, the circuit
becomes more Linear as Qin decreases.
S-PARAMETER CALCULATION:

8. INPUT IMPEDENCE OUTPUT IMPEDENCE
PARALLEL RESISTANCE: PARALLEL CAPACITANCE: