70 GHz receivers for Planck Mission

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ESA Planck Overview

Planck Overview

The Universe is filled with radiation. Behind all other radiative objects lies the footprint of the early Universe, Cosmic Microwave Background (CMB). CMB radiation comes from every direction in the sky with almost the same brightness. CMB radiation can be characterised as three Kelvin blackbody radiation according to Planck's radiation law composed by German scientist Max Planck in 1900. However, by measuring the apparent temperature of the CMB all over the sky, tiny differences, as small as one part of a million, can be found from place to place. By measuring these differences, information about early universe as well as many other astronomical and cosmological questions can be answered.

From technical point of view, the aim of the European Space Agency (ESA) Planck mission, to be launched in May, 2009, is to measure the CMB anisotropy with a great angular resolution of 10' and temperature sensitivity of 10 K per pixel. The Planck spacecraft will have two instruments on-board: Low Frequency Instrument (LFI) and High Frequency Instrument (HFI). Both instruments will utilise a common 1.5 m aperture off-axis reflector antenna. LFI will have channels at 30, 44, and 70 GHz. HFI will have channels at 100, 143, 217, 353, 545, and 857 GHz.

The Finnish involvement, which was originally initiated by MilliLab, is very significant both in the areas of instrument building and cosmology and astronomy. All the critical parts of the 70 GHz receivers have been built by the Finnish instrument team, formed by MilliLab, VTT and DA-Design Ltd. Data processing, cosmology, and astronomy work associated with Planck mission will be performed by the Department of Physics, University of Helsinki, Helsinki Institute of Physics, Metsähovi Radio Observatory, Tuorla Observatory and Observatory, University of Helsinki.

Technical Description

Simplifying, a Planck receiver resembles a good old crystal radio. This analogy is illustrated in Fig. 1. In the crystal radio, the wanted signal is detected using a single crystal and a suitable tuning network. In the Planck receiver, extremely weak signal has to be amplified (amplification factor 500 000) before the 70 GHz signal is detected using a diode, the modern version of the crystal. The sensitivity of the receiver is so good that even radiation emitted by human body can be measured.

Figure 1: Principle of Planck LFI receiver.

Because the observed signal is very weak special emphasis is placed on the noise performance and the stability of the receiver. As in all space equipment, size and power consumption of the device are also minimised. The solution for the problems above was the use of Monolithic Microwave Integrated Circuits (MMIC), which were manufactured using an Indium Phosphide (InP) High Electron Mobility Transistor (HEMT) technology.

Contribution of the Finnish LFI team

Finnish LFI team designed and manufactured so called front-end (FEM) and back-end modules (BEM) for the 70 GHz channel. All together six of both were integrated in the LFI. The FEM consists of hybrids, amplifiers and phase shifters. Final detection and signal analysis will take place in the BEM. The key components of the modules were the InP MMIC low noise amplifiers (LNA, see Fig. 2) and phase shifters.

Figure 2. 70 GHz InP MMIC low noise amplifier containing four HEMT transistors. The size of the device is 2.1 mm x 0.8 mm.

Several MMIC designs were made by the Finnish team. Main emphasis was placed on the LNA designs at 70 GHz to achieve the low noise and low power consumption requirements. Because InP processes were more or less experimental at the time, great deal of work was done in the area of modelling small-signal and noise properties of InP transistors. This was done by characterising the devices with noise parameter measurements at 50-75 GHz and scattering parameter measurements up to 110 GHz (Fig. 3).


Figure 3. 70 GHz MMIC on-wafer testing at MilliLab.

The FEM and BEM blocks manufactured by DA-Design are shown in Figs. 4 and 5. LNAs and other MMIC chips were placed inside of these assemblies. Both modules were designed in such a way, that the parts were inter-changeable in case of malfunction or flaw in a part. This was especially important with the parts containing the LNAs (so-called amplifier chains) in the FEMs (Fig. 4 in front and Fig. 6), because it was possible to try out several amplifier chains and choose the best possible ones for the modules placed in the Planck spacecraft.

Figure 4. Mechanical structure of a one half of the 70 GHz FEM developed by MilliLab and DA-Design. The module is the size of a match box and it weighs 42 grams.

Figure 5. Mechanical structure of the 70 GHz BEM developed by MilliLab and DA-Design. The module weighs 154 grams.

Figure 6. Magnified view of one of the amplifier chains inside a FEM containing two LNAs (on left and in middle) and one phase shifter (on right). Gold wires (seen on the top part of the image) are used for connecting the power supply to the MMICs.

In order to improve signal-to-noise ratio of the receiver by reducing LNA's own noise contribution, the whole FEM will be cooled to 20 K temperature in the Planck spacecraft. The amplified signals are transferred to the BEMs for detection via 1.5 m long waveguides. The BEMs are kept at 300 K in the spacecraft. In order to get an accurate picture of the 70 GHz receiver performance before integration to the LFI, the receiver had to be tested in conditions as similar to the actual operating conditions in space as possible. This was done at DA-Design in a large vacuum chamber with suitable cryogenic coolers to achieve the low temperature for the FEMs (Fig. 7). The MMICs themselves had been pre-tested in MilliLab's cryogenic on-wafer test station at 20 K.

Figure 7. Two full 70 GHz Planck receivers ready for cryogenic testing at DA-Design. The FEMs are located on extreme left in the photograph and the BEMs on extreme right. The modules are connected together with 1.5 m long waveguides covered in Mylar radiation shielding.

Contacts

Jussi Tuovinen, Vice President, R&D Microtechnologies and Sensors, email: jussi.tuovinen@vtt.fi
Jussi Varis, Senior Research Scientist, Sensors and Wireless Devices, email: jussi.varis@vtt.fi

Planck related publications

  1. Tanskanen, J.M., Kangaslahti, P., Ahtola, H., Jukkala, P., Kartaavi, T., Lahdes, M., Varis, J., and Tuovinen, J. 2000. Cryogenic Indium Phosphide HEMT Low-Noise Amplifiers at V-Band. IEEE Trans. Microwave Theory Tech. 48, pp. 1283-1286.
  2. Tuovinen, J., Varis, J., Lahdes, M., Karttaavi, M., and Hakojärvi, H. 2000. Methods for On-Wafer Testing of Cryogenic Integrated Circuits at Millimetre Waves. In: Armandillo, E. (ed.). 4th European Workshop on Low Temperature Electronics - WOLTE 4, WPP-171. Noordwijk, ESTEC. Pp. 157-162.
  3. Tuovinen, J., Kantanen, M., Karttaavi, T., Karvonen, A., Lahdes, M., Varis, J., Vähä-Heikkilä, T., Hughes, N., Jukkala, P., and Sjöman, P. 2003. Advances in Millimetre Wave Low Noise Receivers and On-Wafer Test Methods. In: Akaike, M., Itoh, T., & Wakama, H. (ed.). The 5th Topical Symposium on Millimeter Waves, TSMMW 2003. Yokosuka, Japan. Pp. 171-174.
  4. Mennella, A., Bersanelli, M., Butler, R.C., et al. 2003. Advanced Pseudo-Correlation Radiometers for the Planck-LFI Instrument. In: J. Mallat, A. Räisänen, J. Tuovinen (ed.). 3rd ESA Workshop on Millimetre Wave Technology and Applications: Circuits, Systems, and Measurement Techniques, WPP-212. MilliLab, Espoo, Finland. Pp. 69-74.
  5. Sjöman, P., Hughes, N.J., Jukkala, P., Ovaska, S., Varis, J., and Tuovinen, J. 2003. An Ultra Low Noise Cryogenic 70 GHz Wide Band Continuous Comparator Receiver. In: J. Mallat, A. Räisänen, J. Tuovinen (ed.). 3rd ESA Workshop on Millimetre Wave Technology and Applications: Circuits, Systems, and Measurement Techniques, WPP-212. MilliLab, Espoo, Finland. Pp. 75-80.
  6. Vähä-Heikkilä, T., Varis, J., Hakojärvi, H., and Tuovinen, J. 2003. Cryogenic On-Wafer Measurements at W-band. In: J. Mallat, A. Räisänen, J. Tuovinen (ed.). 3rd ESA Workshop on Millimetre Wave Technology and Applications: Circuits, Systems, and Measurement Techniques, WPP-212. MilliLab, Espoo, Finland. Pp. 435-439.
  7. Tuovinen, J., Hughes, N., Jukkala, P., Kangaslahti, P., Karttaavi, T., Sjöman, P., and Varis, J. 2003. Technology for Millimetre Wave Radiometers. In: L.-P. Schmidt and J. Richter (ed.). Proceedings of the 33rd European Microwave Week, vol. 2. München, Germany. Pp. 883-886.
  8. Vähä-Heikkilä, T., Varis, J., Hakojärvi, H., and Tuovinen, J. 2003. Wideband Cryogenic On-Wafer Measurements At 20-295 K and 50-110 GHz. In: L.-P. Schmidt and J. Richter (ed.). Proceedings of the 33rd European Microwave Week, vol. 3. München, Germany. Pp. 1167-1170.
  9. Karvonen, A., Varis, J., Hakojärvi, H., and Tuovinen, J. 2003. Verification of Cryogenic On-Wafer Measurements for Space Applications. In: Proc. of the 54th International Astronautical Federation Congress. Bremen, Germany.
  10. Karvonen, A., Varis, J., Hakojärvi, H., and Tuovinen, J. 2004. Accuracy Condiderations of Cryogenic Noise Temperature Measurements at V-band. In: K. Mizuno and J.-W. Ra (eds.). Technical Digest of the International Joint Conference of the 6th Topical Symposium on Millimeter Waves - TSMMW2004. Yokosuka, Japan. Pp. 180-183.
  11. Tuovinen, J., Varis, J., Hughes, N., Jukkala, P., Sjöman, P., Ovaska, S., Laaninen, M., Mandolesi, N., Bersanelli, M., Butler, C., and Hoyland, R. 2004. Planck Mission With Advanced Cryogenic mm- and Submm-Wave Receiver Arrays. In: D. Williamson and M. Fischman (eds.). 2004 IEEE Aerospace Conference Proceedings, vol. 2. Big Sky. MT, USA. Pp. 741-746.
  12. Jukkala, P., Hughes, N., Laaninen, M., Kilpiä, V.-H., Tuovinen, J., Varis, J., and Karvonen, A. 2004. Planck - Mission and Technology. In: M. Lahdes (ed.) URSI/IEEE XXIX Convention on Radio Science. VTT Symposium 235. VTT Technical Research Centre of Finland, Espoo, Finland. P. 133.
  13. Varis, J., Hughes, H., Jukkala, P., Laaninen, M., Kilpiä, V.-H., Pulli, T., Lyytikäinen, A., and Tuovinen, J. 2005. Planck Mission With Cryogenic Low-Noise Receiver at 70 GHz. In: GigaHertz 2005. Uppsala, Sweden. Pp. 54-57.
  14. Bersanelli, M., Aja, B., Artal, E., et al. 2005. Planck-LFI: instrument design and ground calibration strategy. Proceedings of the European Microwave Association, 1. Pp. 189-195.
  15. Laaninen, M., Jukkala, P., Hughes, N., Varis, J., and Tuovinen, J. 2006. Results of the Planck 70 GHz Receiver Protoflight Model Test Campaign. Submitted to 4th ESA Workshop on Millimetre-Wave Technology and Applications, WPP-258. Espoo, Finland. Pp. 475-479.
  16. Mennella, A., Aja, B., Artal, E., et al. 2006. Calibration and Testing of the Planck-LFI QM Instrument. In: Mather, J.C., MacEwen, H.A., de Graauw, M.W.M. (ed.). Proceedings of SPIE, Vol. 6265, Space Telescopes and Instrumentation I: Optical, Infrared, and Millimeter. Doc. nr. 62650G.
  17. Varis, J. 2006. Herkkyys tuo tarkuutta. Prosessori. Vol. 26, No. 11, pp. 40-42. (in Finnish)
  18. Varis, J. 2006. Planck Mission 70 GHz Receivers. ERCIM News. No. 67 (October 2006), p. 61.
  19. Varis, J., Hughes, N.J., Laaninen, M., et al. 2009. Design, development and verification of the Planck Low Frequency Instrument 70 GHz Front-End and Back-End Modules. 2009 JINST 4, T12001.
  20. Meinhold, P., Leonardi, R., Aja, B., et al. 2009. Noise properties of the Planck-LFI receivers. 2009 JINST 4, T12009.
  21. Zonca, A., Franceschet, C., Battaglia, P., et al. 2009. Planck-LFI radiometers' spectral response. 2009 JINST 4, T12010.
  22. Mennella, A., Villa, F., Terenzi, L., et al. 2009. The linearity response of the Planck-LFI flight model receivers. 2009 JINST 4, T12011.
  23. Terenzi, L., Salmon, M.J., Colin, A., et al. 2009. Advanced modelling of the Planck-LFI radiometers. 2009 JINST 4, T12012.
  24. Battaglia, P., Franceschet, C., Zonca, A., et al. 2009. Advanced modelling of the Planck-LFI radiometers. 2009 JINST 4, T12014.
  25. Terenzi, L., Lapolla, M., Laaninen, M., et al. 2009. Cryogenic environment and performance for testing the Planck radiometers. 2009 JINST 4, T12015.