Impedance Matching of 640 GHz SIS Mixer Impedance Matching of 640 - - PowerPoint PPT Presentation

http://smiles.tksc.jaxa.jp http://smiles.tksc.jaxa.jp/~sis

Ken’ichi Ken’ichi KIKUCHI KIKUCHI 1, Seikoh , Seikoh ARIMURA ARIMURA 1, J unji , J unji INATANI NATANI 1, Yasunori Yasunori FUJ II FUJ II 1,2

1,2, Toshiaki SUZUKI

, Toshiaki SUZUKI 3, Akiko IWAMOTO , Akiko IWAMOTO 3, , and Akihito and Akihito YAMAMOTO AMAMOTO 3

1 J

apan Aerospace Exploration Agency

2 J

apan Communication Equipment Co., Ltd

3 Mitsubishi Electric TOKKI System Co., Ltd

Impedance Matching Impedance Matching Impedance Matching Impedance Matching of 640 GHz SIS Mixer

• f 640 GHz SIS Mixer
• f 640 GHz SIS Mixer
• f 640 GHz SIS Mixer

in a High IF Band of 11 in a High IF Band of 11 in a High IF Band of 11 in a High IF Band of 11-

• 13 GHz

13 GHz 13 GHz 13 GHz

Abstract

Two 640 GHz SIS mixers are used for SMILES, an atmospheric research mission to be aboard the International Space Station. Those SIS mixers, are operated at a relatively high IF band of 11-13 GHz, which is selected from the scientific reason of the mission. That high IF frequency, however, makes it more difficult to match the SIS device to the subsequent 50 Ω IF line. In addition to an impedance difference in real part, parasitic effects due to bonding wires, RF choke circuit as well as the capacitance of the SIS junctions will play an important role. When the IF matching is poor, the SIS mixer under test often exhibits significant gain ripples in its IF characteristics. A solution for that is to insert a proper impedance transformer between the SIS mixer device and the IF output port and compensate the undesirable parasitic effects. To experimentally derive the output impedance of the SIS device, we have repeated measurements of the receiver gain with respect to an SIS device combined with several different types of matching transformers. We utilized the set of data with different IF characteristics to determine the SIS mixer parameters by means of a fitting technique. This has worked well and allowed us to establish the SIS mixer model to reproduce the measured data. With a proper impedance transformer designed based on the above fitting results, we successfully realized a small ripple and better flatness in the gain profiles of the mixer.

640 GHz SIS Mixer for SMILES 640 GHz SIS Mixer for SMILES

100 150 200 250 300 350 620 630 640 650 660

LO frequency (GHz) TRX,DSB (K)

50 100 150 200 250 300 0.5 1 1.5 2 2.5 3 3.5 4

I (µA) V (mV)

Characteristics of EM Mixer Receiver

Receiver Noise (DSB) I-V Characteristics USB Mixer LSB Mixer (LO-pumped)

LO : 637.32 GHz IF : 11-13 GHz

SIS Junction: Nb/AlOx/Nb Junction Size: ~1 x 1 µm2 Current Density: 6-7 kA/cm2 RF Matching: PCTJ

SIS Mixer (Engineering Model) IF port GND 500 µm SIS Device

Sideband Separation: Quasioptical separation with FSP

In some cases of high IF system, the frequency separation between upper and lower sideband is not negligible as compared with the RF band- width of an SIS mixer. For SMILES, each mixer is selected to have good performance at each band.

Analytical Model of SIS Mixer Analytical Model of SIS Mixer

5 mm

50 Ω

SIS Junction with Superconducting Microstrip-line Embedding Impedance at Feed-point (Ｉ ncluding Bonding-wire)

SIS Device + Bonding Wire

SuperMix HFSS (based on measurement)

Zout

Measurement

Impedance Transformer

SIS device and bonding wire.

Both SIS device and IF impedance transformer are installed in a mixer block.

Connection between ribbon wire and SMA connector pin.

Zload

IF G IF G IF G IF G IF G IF G IF G IF G IF G V I V I V I

FLO 1 FLO 2 FLO 3

Transformer 1

SIS Device A SIS Mixer

R r

S I S M i x e r H E M T A m p .

• ut

load

• ut

load

Z Z Z Z R + − =

∗

( )

2

1 rR G G − =

( )

2

1 rR G G + =

R e c e i v e r G a i n G I F Transformer 2 Transformer 3

Receiver measurements were repeated with respect to an SIS device combined with several different types

• f transformers.

Determination of SIS device Determination of SIS device parameters by Fitting Analysis parameters by Fitting Analysis

LO Frequency Transformer Type

Receiver gains and I-V characteristics, measured with different types of transformers and different LO frequencies, were simultaneously fitted to determine SIS device parameters.

Data Model

• 12
• 10
• 8
• 6
• 4
• 2

10 10.5 11 11.5 12 12.5 13 13.5 14

Frequency (GHz) Gain (dB)

5 Ω T h r u L i n e

• 12
• 10
• 8
• 6
• 4
• 2

10 10.5 11 11.5 12 12.5 13 13.5 14

Frequency (GHz) Gain (dB)

T r a n s f

• r

m e r N

• .

1

• 1
• 12
• 10
• 8
• 6
• 4
• 2

10 10.5 11 11.5 12 12.5 13 13.5 14

Frequency (GHz) Gain (dB)

T r a n s f

• r

m e r N

• .

1

• 2

0.05 0.1 0.15 0.2 0.25 0.3 0.5 1 1.5 2 2.5 3 3.5 4

I (mA) V (mV)

I

• V

C h a r a c t e r i s t i c R e c e i v e r G a i n ・ Jc = 6813 A/cm2, Rn = 15.9 Ω ・ Relatively high dynamic resistance of 550 Ω at bias point

• 12
• 10
• 8
• 6
• 4
• 2

10 10.5 11 11.5 12 12.5 13 13.5 14

Frequency (GHz) Gain (dB)

• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2 0.4 0.6 0.8 1

• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2 0.4 0.6 0.8 1

0.2 0.5 1.0 2.0 5.0

• 2.0
• 1.0
• 0.5
• 0.2

0.2 0.5 1.0 2.0

Zout (output imped- ance of SIS device) in 10-14 GHz。

Example of Fitting Result : Example of Fitting Result : SIS Device A with FLO = 654 GHz

Receiver gain profile with impedance transformer No. 3-1

Example of Fitting Result : Example of Fitting Result :

Data Model

I

• V

C h a r a c t e r i s t i c R e c e i v e r G a i n ・ Jc = 5962 A/cm2, Rn = 13.7 Ω ・ Relatively low dynamic resistance of 150 Ω at bias point.

0.05 0.1 0.15 0.2 0.25 0.3 0.5 1 1.5 2 2.5 3 3.5 4

I (mA) V (mV)

• 18
• 16
• 14
• 12
• 10
• 8
• 6
• 4

10 10.5 11 11.5 12 12.5 13 13.5 14

Frequency (GHz) Gain (dB)

5 Ω T h r u L i n e

• 18
• 16
• 14
• 12
• 10
• 8
• 6
• 4

10 10.5 11 11.5 12 12.5 13 13.5 14

Frequency (GHz) Gain (dB)

T r a n s f

• r

m e r N

• .

1

• 2
• 18
• 16
• 14
• 12
• 10
• 8
• 6
• 4

10 10.5 11 11.5 12 12.5 13 13.5 14

Frequency (GHz) Gain (dB)

T r a n s f

• r

m e r N

• .

2

• 2
• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2 0.4 0.6 0.8 1

• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2 0.4 0.6 0.8 1

0.2 0.5 1.0 2.0 5.0

• 2.0
• 1.0
• 0.5
• 0.2

0.2 0.5 1.0 2.0

Receiver gain profile with impedance transformer No. 3-2

• 18
• 16
• 14
• 12
• 10
• 8
• 6
• 4

10 10.5 11 11.5 12 12.5 13 13.5 14

Frequency (GHz) Gain (dB)

SIS Device B with FLO = 618 GHz

Zout (output imped- ance of SIS device) in 10-14 GHz。