70-90GHz Self-Tuned Polyphase Filter for Wideband …...70-90GHz Self-Tuned Polyphase Filter for Wideband I/Q LO Generation in a 55nm BiCMOS Transmitter Farshad Piri1, E. Rahimi2,

70-90GHz Self-Tuned Polyphase Filter for Wideband I/Q LO Generation in a 55nm BiCMOS Transmitter

Farshad Piri1, E. Rahimi2, M. Bassi3, F. Svelto2, A. Mazzanti2

[email protected]

September 23-26, 2019

ESSCIRC/ DE , Cracow, PolandESS RC 2019

1 Infineon Technologies AG, Linz, Austria2 University of Pavia, Pavia, Italy3 Infineon Technologies AG, Villach, Austria

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Outline

Introduction

Quadrature generation techniques

Tunable Polyphase filter for I/Q generation

Mm-Wave Phase detector

Measurements and Comparison table

Summary

ESSCIRC/ DE , Cracow, PolandESS RC 2019 2 of 19Farshad Piri

Wireless Backhaul in E-Band


Base station density increase with evolution of mobile networks

Micro-Femto cells require cheap, high-capacity, short-reach backhaul links

mm-Wave E-Band (71-76/81-86 GHz) available for PtP wireless backhaul

Low power consumption, compact size and high volumes motivate BiCMOS backhaul transceivers

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5G mm-Wave Bands


Ultra-Wide Channels250-500-5000MHzLow,Med-Order ModulationQPSK-QAM16-QAM64-QAM128

Wide Channels3.5-56-112MHzHigh-Order ModulationQAM64-QAM256-QAM1024

Narrow Channels3-5-40MHzmedium-Order ModulationQAM64-QAM256

DC 10 20 30 40 50 60 70 80 90

Freq. (GHz)

81 -

86 G

Hz

71 -

76 G

Hz

38.6

- 40

.0 G

Hz37

.0 -

38.6

GHz

40.5

- 43

.5 G

Hz

2 G

Hz3

GHz

6 G

Hz5

GHz

11G

Hz

18G

Hz

23G

Hz

Sub-6GHz MicroWave Mm-Wave

31.8

- 33

.4 G

Hz27

.5 -

28.3

GHz

24.2

- 27

.5 G

Hz

57 -

66 G

Hz

E-BandV-BandC,Ku,Ka,Q BandsS,C Bands This Work

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Direct Conversion TX

Absence of IF mmWave stages allows wide-band Power and area saving Key issue is quadrature LO generation directly at E-band PA challenging in silicon to deliver high Pout with good efficiency


gm

G

G

S

PA

LO I

LO Q

PA

BB I

BB Q

gm

70-90 GHz LO

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Active VCO + divider Quadrature VCOs

Passive Quadrature Couplers (Lange, branch-line,

Hybrid) All pass networks (LC and RC Polyphase

Filters)

E-band Quadrature LO Generation

Quadrature hybrids disregarded because of large footprint, limited accuracy (φe≃2-3°) and limited bandwidth

Polyphase filters (PPF) are very compact and can reach 40dB Image Rejection Ratio (φe <1°) but needs several stages (>3) considering PVT variations



Quadrature hybrids disregarded because of large footprint, limited accuracy (φe≃2-3°) and limited bandwidth

Polyphase filters (PPF) are very compact and can reach 40dB Image Rejection Ratio (φe <1°) but needs several stages (>3) considering PVT variations


0

10

20

30

40

50

60

70

30 40 50 60 70 80 90 100 110 120

Imag

e Re

ject

ion

Ratio

[dB]

Freq. [GHz]

slow, 110° typ, 27° fast, -40°

Desired BW

3-Stage PPF

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Inp

Inn

Ip

Qp

+

+

-

-

RC

Type-A PPF (∆Amp =0)


1-stage (low-loss) MOSFET-C Polyphase filter (C=28fF) Phase detector measures quadrature deviation, and error Amp derives the

PPF(Vtune) to maintain minimum phase error Calibration loop needs 16mW only Transformer-based interface network for flat amplitude response, Wide BW.


Vtune

buff

buff

Amp

to Mixer

LO_I

LO_Q

to Mixer

1-stage tunable PPF

70-90 GHz

I

Q

Phase Detector

Vtune1 Vtune2 Vtune3

IRR[

dB]

Image Rejection Ratio

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Vtune

buff

buff

Amp

to Mixer

LO_I

LO_Q

to Mixer

1-stage tunable PPF

70-90 GHz

I

Q

Phase Detector

Loop Gain


Loop Gain of >30dB required to reduce 20° Open loop phase error to <1°(IRR>40dB)

GLoop= KPD.AV.KPPF

Phase detector Gain (KPD) has to be maximized to reduce offset/mismatch effect KPPF is about 100 [°/V] KPD.AV designed to achieve >0.3 [V/°]

KPD

AV

KPPF

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Quadrature Phase Detector


Phase detector realized with – Gilbert cells driven by exchanged LO signals Matched loading for LO_I and LO_Q Cancels the effect of the phase skew (∆φ) introduced by each cell at the output

M1 M2

LO_I LO_Q

Gm gm

AB

gm

Vout

LO_Q LO_I

Vcc

Ia+ Ia-Ib+ Ib-IP IN

IDC

Q1a Q1b

Q2a,b

QP QN

Ia+ Ia-

QPQ2c,d

𝐋𝐋𝐋𝐋_𝐈𝐈:𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀(𝛚𝛚𝐋𝐋𝐋𝐋𝐭𝐭)

𝐋𝐋𝐋𝐋_𝐐𝐐:𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀(𝛚𝛚𝐋𝐋𝐋𝐋𝐭𝐭 + 𝛟𝛟𝐞𝐞)

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Phase Skew in each Gilbert Cell


Mismatch between rbcπ of Q1-Q2 and Caps Cxy responsible for large ∆φ (≈78°) (Ia+−Ia−) ∝ sin(ϕe − ∆𝛟𝛟) (Ib+−Ib−) ∝ sin(ϕe + ∆𝛟𝛟)

Output of each cell is not zero even if LO_I and LO_Q are in quadrature (φe=0)

IPIN

IDC

Q1a Q1b

Q2a,b

QP QN

Ia+ Ia-

QPQ2c,d

rb1

cπ1

rb2

cπ2cx cy

M1 M2

LO_I LO_Q

Gm gm

AB

gm

Vout

LO_Q LO_I

Vcc

Ia+ Ia-Ib+ Ib-

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𝐋𝐋𝐋𝐋_𝐈𝐈:𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀(𝛚𝛚𝐋𝐋𝐋𝐋𝐭𝐭)


Farshad Piri

Phase Skew in each Gilbert Cell


By summing the output currents with M1-M2, the detector output voltage is: 𝑉𝑉𝑜𝑜𝑜𝑜𝑜𝑜 ∝ (Ia+ − Ia−) + (Ib+−Ib−) ∝ cos(∆𝛟𝛟)sin(ϕe)

∆φ does not introduce systematic phase error, but reduces severely the detector gain (cos(78 °)=0.2)

IPIN

IDC

Q1a Q1b

Q2a,b

QP QN

Ia+ Ia-

QPQ2c,d

rb1

cπ1

rb2

cπ2cx cy

M1 M2

LO_I LO_Q

Gm gm

AB

gm

Vout

LO_Q LO_I

Vcc

Ia+ Ia-Ib+ Ib-

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Δϕ=k if k<1

π2 +k− k2−1− arcsin k−1 if k>1

k=π CX,Y Aeff fLO

IDC

𝐋𝐋𝐋𝐋_𝐈𝐈: 𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀(𝛚𝛚𝐋𝐋𝐋𝐋𝐭𝐭)


Farshad Piri

Final phase detector


Explicit resistors (R) added in series to the switching transistors, sized to cancel the intrinsic mixers skew (∆φ≈0°).

Detector gain restored, key to limit the effect of random offset (Vos) From Monte-Carlo simulations, w./.o. R, φe_Vos=3.5°, w. R, φe_Vos=0.85°

M1 M2

LO_I LO_Q

Gm gm

AB

gm

Vout

LO_Q LO_I

Vcc

RR

vos

8µA/°

30µA/°


PA Core - Single-Path


T1 (1:1 xfrm) matches 50Ω off-chip load to 70Ω differential load resistance Common-Base output stage (Q1A,B) with current clamping (LE) Inter-stage matching (T2) introduces 3x AC current gain Cascode driver (Q2A,B-Q3A,B) in Class-A for high linearity Varactors (not shown) at collectors of Q3A,B for AM-PM correction


Two-Way PA

G

G

S

Combiner

PA

LO I

LO Q

PAgm

gm

Signal Path of TX


Combiner and Splitter for two-way Power combining (similar PA cores) Up-Conversion with Double-Balance Gilbert Mixer structure. Programmable gain configuration with variable RE is employed to compensate the gain variation of

chain in corners.

LO IPLO IN

IDC

Q1 Q2

Q3 Q4 Q5 Q6

BB IP BB IN

LO IP

IDC

RE


Chip Microphoto

Technology, 55nm SiGe BiCMOS by STM fT=320 GHz, fMAX=370 GHz Core Area of full TX is 690um x 320um Core Area of IQ LO Generator part is 170µm x 300 µm


Buffer Q

Buffer I

2-Way PAMixerPPF

PD Combiner


Measurements - Spectrum finput=80 GHz PBB= 0 dBm fBB=100 MHz

POut= 20 dBm IRR= 44dB LO leakage=-30dBc


Buffer Q

Buffer I

2-Way PAMixerPPF

PD Combiner

PSG+x6 multiplier

70-90GHzLO

fBB (1-100MHz)

± I ± Q


Measurements–IRR, Pout and OP1dB

IRR>40dB for 70-90GHz when Loop is on. Negligible impact of the input/output Power on IRR for different TX gains. OP1dB > 18dBm with -3dB bandwidth from 71GHz to > 90GHz with Pimage<-20 dBm.


This Work [4](TMTT’18)

[3](JSSC’15)

[2] (JSSC’18)

[9](TMTT’16)

[10](TMTT’13)

Tech. 55nm SiGeBiCMOS

130nm SiGeBiCMOS

40nm CMOS 90nm SiGe 130nm SiGe 65nm CMOS

Freq. [GHz] 70-90 40-80 71-86 71-86 71-76/81-86 63-69GHzGain [dB] 17-25 - 11 22.8 38 33

Power[mW]

800 @ OP1dB

32 102 330 1350 115mW

Peak OP1dB[dBm]

20.5 - 8.8 7.4-10 (Psat)

16 8.3dBm

Efficiency [%] 14 - 7.4 3 3 5.9

IRR [dB] ≥40 ≥30 (44-76GHz)

≥30 ≥26 ≥26 ≥40

Architecture Direct Conv.

IQ LO gen. only

Direct Conv. Weaver TX

Heterodyne TX

+ LO Synth.

Sub Harmonic Direct Conv.

Performance Summary

Compared to works in E-band +10dB IRR without calibration, higher OP1dB and efficiency levels.

Higher-order Modulations enabled thanks to large dynamic range.ESSCIRC/ESSDERC 2019, Cracow, Poland 19 of 19Farshad Piri

Conclusions

5G communication systems require high purity local oscillator signals.

Providing wideband quadrature LO signal with good IRR is challenging for higher-ordermodulations.

Delivering Large output power with high-efficiency in PA in silicon is limited.

A single-stage low-loss PPF stage in combination with a calibration loop is proposed toachieve both wide bandwidth, low loss, phase noise and high IRR.

From measurements, the TX performs well in compare to previously reported realizationsin terms of Image Rejection Ratio, Pout and efficiency

ESSCIRC/ESSDERC 2019, Cracow, Poland 20 of 19Farshad Piri

Thank You

Questions ?

ESSCIRC/ESSDERC 2019, Cracow, Poland 21 of 20Farshad Piri

Documents

70-90GHz Self-Tuned Polyphase Filter for Wideband …...70-90GHz Self-Tuned Polyphase Filter for Wideband I/Q LO Generation in a 55nm BiCMOS Transmitter Farshad Piri1, E. Rahimi2,