SIS mixers for 1mm bandA. Navarrini, G. Engargiola, R. Plambeck (Berkeley)

N. Wadefalk (Caltech)

• short term: increase bandwidth of existing BIMA mixers to 4 GHz

• long term: develop new generation of 1mm mixers using UVa SIS mixers

SIS junc tio n

Fro nt b lo c k

SISb ia s

Alig nm e nt p ins

Rea r b lo c k

50 O hmIF ne two rk

C a vitie s fo rfixe d m a g ne t

WGc a vity

To IF Am p lifie r

1 m m M ixe r Blo c k

Current BIMA 1mm receivers

• DSB, fixed-tuned SIS mixers

• single SIS junction devices fabricated by G. Engargiola at U. Illinois

• 800 MHz IF band, 1.4 - 2.2 GHz (limited by IF amp)

5.5 K

4.5 K

3.6 K

DSB receiver temperatures ~ 50 to 80 K(measured outside dewar, including all optics losses)

Need to replace narrowband IF amplifier

• ALMA solution is to build I.F. amplifier from discrete transistors– more flexibility in matching impedance of SIS junction

• our preferred solution is to use InP MMIC– WBA13, developed by Weinreb and Wadefalk for ATA

– 35 dB gain, noise temp 3-6 K

– 10-20 mW power dissipation

Comparison of amplifier gains, noise temperatures

ALMA Band 6 amplifier, designed for 4-12 GHz

WBA13 MMIC, designed for 0.5-11.5 GHz

Gene Lauria, ALMA Band 6 PDR, Apr 2004 Wadefalk and Weinreb

Option 1: replace amplifier on 12 K stage with MMIC module

(WBA13 amplifier module provided by N. Wadefalk)

Fe e d -ho rn Sta in le ss ste e lc o a xia l c a b le

WBA13 a m p lifie r m o d ule

SIS m ixe r b lo c kIF o utp utDC m a g ne t

Option 1: Trcvr DSB measured with 0-6 GHz I.F.

filter comparable to narrowband results

Option 1: gain and noise from 0-9 GHzripple tolerable from 225-240 GHz, bad outside this range

0 1 2 3 4 5 6 7 8 9

-130

-120

-110

-100

-90

-80

260 GHz

SIS Mixer cascaded with WBA13 amplifier moduleJunction from wafer 5: R

N=14.2 Ohm - Block: 31-015-1

SIS: Vdc

=2.0 mV ; ILO

=35 uA;Mixer Temp: 4.7 K; 2" stinless steel coax. cable+50 Ohm IMN + JCA amp. 1-10 GHz

Cold Load Ambient Load

IF O

utpu

t P

ower

[dB

m]

IF Frequency [GHz]

0 1 2 3 4 5 6 7 8 90

50

100

150

200

250

300

350

400

260 GHz

Trec,DSB(0-6 GHz)=85 KT

rec,DSB(1.2-2.2 GHz)=83 K

Trec,DSB(2-4 GHz)=87 KTrec,DSB(4-8 GHz)=88 K

SIS Mixer cascaded with WBA13 amplifier moduleJunction from wafer 5: R

N=14.2 Ohm - Block: 31-015-1

SIS: Vdc

=2.0 mV ; ILO

=35 uA;Mixer Temp: 4.7 K; 2" stinless steel coax. cable+50 Ohm IMN + JCA amp. 1-10 GHz

Tre

c,D

SB

[K]

IF Frequency [GHz]

225 GHz

260 GHz

Option 2: integrate MMIC directly into mixer block

M ixe rc h ip

WBA12 WGc a vity

M ixe rb ia s c irc u it

WBA12b ia s c irc u it

IF o utp utIF ne two rk

C a vityfo r fixe dm a g ne t

• MMIC tended to oscillate; had to switch from WBA13 to lower-gain WBA12

• mixer block at 4.65 K instead of 3.85 K

• gain ripple still a problem

Option 3: incorporate pre-packaged WBA13 (ATA module) into thermally-split block

3.8 K12 K

Option 3: DSB noise temperatures0-6 GHz I.F. filter

200 210 220 230 240 250 260 270

40

50

60

70

80

90

SIS Mixer cascaded with WBA13 module using thermally split blocks

Tre

c,D

SB

[K]

LO Frequency [GHz]

Option 3: gain, noise from 0-6 GHz(ripple much improved, but gain falls off above 3 GHz)

0 1 2 3 4 5 6

-90

-85

-80

-75

-70

-65

-60

260 GHz

SIS: Vdc

=2.3 mV; ILO

=36 uAWBA13: V

d=1.19 V; I

d=31.5 mA

Vga

=0.38 V; Iga

=25.4 uA V

gb=0.38 V; I

gb=25.4 uA

Tphys,mixer

=3.83 K

Cold load Ambient load

IF O

utpu

t P

Ow

er [

dBm

]

IF Frequency [GHz]

0 1 2 3 4 5 60

100

200

300

260 GHz

SIS: Vdc=2.3 mV; ILO=36 uAWBA13: V

d=1.19 V; I

d=31.5 mA

Vga

=0.38 V; Iga

=25.4 uA V

gb=0.38 V; I

gb=25.4 uA

Tphys,mixer

=3.83 K T

rec(0-6GHz)=79 K

Tre

c [K

]

IF Frequency [GHz]

225 GHz

260 GHz

broadening bandwidth of BIMA 1mm mixers to 4 GHz: short term solutions

option advantages disadvantages

1 • no need to rebuild mxr blocks

• no extra heat load on stage 3

• amplifier oscillations unlikely

• huge gain ripples below 220, above 240 GHz

2 • must build new mixer blocks

• increased heat load on stage 3

3 • lower gain and noise ripple • must build new mixer blocks

if we must have 4 GHz bandwidth by Fall 2005, option 1 probably is best

Longer term

• goal: DSB Trcvr = 25 K, 8 GHz I.F. bandwidth • switch to ALMA Band 6 devices

– we have only ~50 usable UI junctions

– NRAO has contracted for 9 UVa wafers, each with 1066 devices (9600 devices); approx 50% are usable

– if necessary, we could contract with UVa for an additional wafer

• construct thermally split block with WBA13 IF amp– operating WBA13 at 12 K reduces heat load on 4 K refrig,

may also improve 1/f gain stability of MMIC

ALMA Band 6 SIS devices

• DSB Trcvr ~ 20 K• series array of 4

junctions – avoids problems with saturation, but requires more LO pwr

Tony Kerr has given us 4 ALMA devices to try

• sideband separation requires complex mixer block, carefully phase-matched preamps

• NRAO estimates ~25% acceptance rate for ALMA mixers

ALMA is building sideband separating mixers, but we would use devices as DSB mixers

from ALMA Band 6 PDR, Apr 2004

ALMA sideband separating mixer blockwith attached preamps

Sensitivity comparisons