Balun design working at 5.8 GHz The substrate is tsmc 0.18um. This balun can be used for input and output matching. Q factor is around 8 ( width of microstrip trace is 12.5 um).

1. Balun
Frankie Nguyen, PhD Candidate
Centre for Technology Infusion (CTI), Melbourne campus, La Trobe
University
20Sept2017

2. Vb
Vdd
P1P2
S1
S2 Return path
for current
(metal)
Interleaved Balun (4 ,6 and 8 rings)
Width of the trace: 12.5um
Size of balun : 150um
Spacing between trace: 4um
Ports: P1, P2, Vb, S2, S1, Vdd
Width of Vb: 2um (M4)
Width of Vdd: 1.5*12.5um
(M4)
Trace: Metal 6

3. 4 ring balun

4. Conventional power amplifer
Ci
VB_PPA
Ci1
VDD
Cm1
VDD
Co1 Co_p
Co_s
Rf
Cf
Cm2
VB_PA
RF_IN
RF_OUT
2fo short
2fo short
M_PAM_PPA

6. Formula
Coupling coefficient factor (k)

7. S6p in Synopsys
160um
8 rings
Gmax
L1 (nH)
L2 (nH)
K factor

8. 4 Rings ( Radius from 110 um to 300 um)
4 Rings
RB (um) Gmax L1(nH) L2 (nH) K factor Q1 Q2
100 -2.27 0.695 0.699 0.54 6.87 7.07
110 -2 0.837 0.843 0.578 7.3 7.52
120 -1.79 0.997 1 0.603 7.86 8.04
130 -1.67 1.16 1.16 0.628 8.08 8.25
140 -1.57 1.32 1.33 0.65 8.23 8.46
150 -1.48 1.51 1.52 0.665 8.57 8.71
160 -1.42 1.7 1.71 0.678 8.78 8.86
170 -1.39 1.9 1.91 0.691 8.7 8.79
180 -1.34 2.12 2.14 0.705 8.86 8.95
190 -1.3 2.35 2.36 0.716 8.91 8.97
200 -1.28 2.59 2.61 0.729 8.82 8.87
210 -1.26 2.86 2.88 0.738 8.83 8.86
220 -1.24 3.15 3.17 0.747 8.79 8.81
230 -1.21 3.47 3.81 0.766 8.57 8.56
240 -1.21 3.79 3.81 0.766 8.51 8.49
250 -1.21 4.16 4.18 0.777 8.25 8.2
260 -1.2 4.56 4.58 0.785 8.08 8.04
270 -1.2 4.99 5.02 0.794 7.86 7.8
280 -1.21 5.49 5.54 0.805 7.44 7.39
290 -1.22 6.06 6.1 0.817 6.98 7.03
300 -1.22 6.73 6.79 0.828 6.66 6.57
6
6.5
7
7.5
8
8.5
9
9.5
0
1
2
3
4
5
6
7
8
100 150 200 250 300
SIZE
4 Ring
L1(nH)
Q1

9. 6 rings ( Radius from 140 um to 280 um)
6 Rings
RB (um) Gmax L1(nH) L2 (nH) K factor Q1 Q2
140 -1.59 1.95 1.95 0.696 7.5 7.58
150 -1.46 2.35 2.34 0.716 8.57 8.71
160 -1.37 2.78 2.77 0.738 8.1 8.19
170 -1.3 3.27 3.26 0.76 8.11 8.22
180 -1.24 3.84 3.82 0.777 8.14 8.25
190 -1.2 4.5 4.49 0.795 7.99 8.1
200 -1.17 5.28 5.26 0.81 7.77 7.89
210 -1.15 6.22 6.21 0.827 7.39 7.48
220 -1.14 7.42 7.37 0.845 6.83 6.96
230 -1.14 9 8.95 0.864 6.08 6.19
240 -1.15 11.3 11.2 0.884 5.19 5.27
250 -1.15 14.4 14.3 0.903 4.32 4.44
260 -1.15 18.3 18.1 0.917 3.57 3.63
270 -1.15 25.1 24.9 0.935 2.55 2.58
280 -1.18 25.9 25.9 0.137
From
280um
become
capacitance
0
1
2
3
4
5
6
7
8
9
0
5
10
15
20
25
30
140 160 180 200 220 240 260
SIZE
6 Ring
L1(nH)
Q1

10. 8 rings (( Radius from 160 um to 230 um)
8 rings
RB (um) Gmax L1(nH) L2 (nH) K factor Q1 Q2
140 NA
150 NA
160 -1.48 3.42 3.45 0.754 7.06 7.08
170 -1.42 4.35 4.39 0.796 6.58 6.56
180 -1.28 5.42 5.46 0.809 7.01 7
190 -1.22 6.91 6.97 0.836 6.61 6.55
200 -1.19 9.06 9.16 0.864 5.84 5.76
210 -1.18 12.6 12.7 0.894 4.66 4.58
220 -1.16 18.2 18.4 0.919 3.52 3.48
230 -1.16 29.3 29.7 0.946 1.99 1.96
240 After that become capacitance
0
1
2
3
4
5
6
7
8
0
5
10
15
20
25
30
35
160 170 180 190 200 210 220 230
SIZE
8 ring
L1(nH)
Q1