Wide band, ultra low noise cryogenic In. P IF amplifiers for the HERSCHEL mission radiometers Isaac López-Fernández, Juan Daniel Gallego, Carmen Diez, Alberto Barcia, Jesús Martín-Pintado Centro Astronómico de Yebes Observatorio Astronómico Nacional Guadalajara, SPAIN Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 1
Outline n n n Introduction Device characterization Amplifier design Amplifier fabrication Amplifier performance l l n Noise and gain measurements Reflection and stability measurements Gain fluctuations measurements Isolator measurements Conclusions Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 2
Introduction: HERSCHEL requirements n n HERSCHEL: Far Infrared and Submillimeter 3. 5 m Telescope orbiting in L 2 with 3 cryogenic instruments HIFI: Heterodyne Instrument for the Far Infrared with 7 dual polarization submillimeter SIS and HEB receivers Our contribution: low noise, wide band 4 -8 GHz cryogenic IF preamplifiers for each mixer channel (14) Sensitive parameters: l l Noise temperature: the contribution to the receiver noise is significant Power dissipation: mission life limited by liquid helium mass Gain fluctuations: impact in the chopping frequency Other mechanical and electrical constraints Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 3
Introduction: CAY experience n More than 150 cryogenic LNAs built for different applications (not including to HERSCHEL developments) l l l l n IRAM: Grenoble, Pd. B interferometer, 30 m (IF amplifiers) ESOC: New Northia DSN antenna (Rosetta, SMART) Burdeos Observatory EMCOR (Atmospheric sensing) PRONAOS (mm receiver in stratospheric balloon) INPE: 14 m Brazil CAY: VLBI receivers (X and K band) Wide experience with HEMT devices l l More than 30 batches of commercial Ga. As transistors tested Several models of In. P transistors measured JPL-TRW (CHOP program): 14 batches, 9 models è ETH Zürich: 7 batches, 4 models è Chalmers University: 1 batch è Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 4
Introduction: Initial developments n n n Prototypes in the 8 – 12 GHz band Successful testing of In. P in this band comparison with Ga. As Demonstration of In. P in the 4 – 8 GHz band Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 5
Device characterization: Transistors Measurement procedures n In. P technology selected based on previous experience in IF amplifiers è n lower power dissipation, factor of 2 better noise, higher gm Cryogenic S parameter measurements to model devices In-house test fixture with microstrip lines to allow two-tier TRL calibration è Device measured with bonding wires è DC and cold. FET complete the small signal model è n Noise model according to Pospieszalski è The noise measured in a wide band test amplifier sets the TD of the model Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 6
EXAMPLE OF CRYOGENIC S PARAMETERS (1 – 40 GHz) MODEL MEASG Circuit model Raw data Time domain filter Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 7
Device characterization: Transistors 0. 19 mm Results TRW T-42 CRYO 3 Ø 200× 0. 1 μm gate Ø Best performance 0. 22 mm TRW T-45 CRYO 4 Ø 200× 0. 1 μm gate Ø Used in DMs Ø Space qualifiable, to be used in FMs Ø CHOP developed ETH T-35 Ø 200× 0. 2 μm gate Ø Experimental transistor Ø Design by request Ø Used in MPAs Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 8
Device characterization: Components n Selection of components based on previous experience at cryogenic temperatu l l n SOTA thick film resistors ATC 111 parallel plate capacitors with CA dielectric ATC 100 multilayer porcelain capacitors RT/Duroid 6002 substrates 20 mils thick Simple models of concentrated elements are adequate for this frequency range Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 9
Amplifier design n n Microstrip hybrid design simulated by MMICAD software Developed cryogenic models for transistors, connectors, critical capacitors, resistors and bonding wires Each In. P device is independently stabilized by resistive loading and inductive feedback Input circuit: wideband noise matching Tuning elements incorporated in the design (adjustable bonding wires, microstrip islands) n n Box resonances avoided with careful EM design and the use of microwave absorbers Multiple bias networks requirements Contribute to the unconditional stability of the amplifier è Comply with EMC mission requirements è Provide ESD protection of sensitive In. P HEMTs è Have a low drain voltage drop è Filter RF è Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 10
Amplifier fabrication: several series n n 37 4 -8 GHz YCF amplifiers fabricated at CAY in different series All processes performed in our labs Design transferred to Alcatel Espacio to build Flight Models Series analyzed here: l l YCF 2 – ETH transistors (Mixer Program Amplifiers) YCF 6 – TRW transistors (Development Models) Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 11
MP amplifier YCF 2 Ø 2 stages ETH 200 µm Ø Gold plated brass Ø 61. 4× 35× 11. 5 mm, 149 g Ø Duroid 6002 substrates DM amplifier YCF 6 Ø 2 stages TRW 200 µm Ø Gold plated aluminum Ø 58× 32× 15 mm, 65 g Ø Duroid 6002 substrates Ø Improved bias circuits Ø Additional cavity for filtering Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 12
Amplifier fabrication: reliability n Reliability is a priority over performance for the selection of components, subs Spatial design è Cryogenic operation è n n Past experience in cryogenic designs obviates most of the work in testing, mod An example: ‘O’ ribbon connection in the SMA tab contact: l l Allows mobility in three axis Excellent electrical properties compared with traditional SMA connections Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 13
Performance: Noise and Gain Measurement procedures n Measurement procedure: Cold attenuator n Two measurement systems available at our labs: l System 350: Older è More pessimistic è Used to keep traceability with past measurements è All noise tests shown here were performed with 350. è l System 1020: Newer calibration. è Gives 0. 75 K better results è n Estimated error (both) 1. 4 K (repetitivity < 0. 2 K) Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 14
Performance: Noise and Gain Results Ø Average of 3. 57 K mean noise in the band for the complete DM series Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 15
Performance: Reflection and Stability n Worst case output reflection l l n n Average MPAs: Average DMs: -14. 3 d. B -13. 0 d. B Model prediction of output return losses needs refinement Isolator at the input (not designed for low input ref. ) n Unconditionally stability for most bias points checked with sliding shorts Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 16
Performance: Gain fluctuations Cryogenic measurements of DMs (TRW transistors) n Characterized by spectral density of normalized gain fluctuations: 1. Measure S 21 @ 6 GHz with HP 8510 VNA (attenuator and air lines) 2. Normalize and FFT each VNA scan (0. 012 -2. 34 Hz) 3. Average 50 spectra and subtract the system fluctuations n Fit, in the region where 1/f noise dominates, the expression β represents the fluctuatons @ 1 Hz and is used as a reference for comparison between amplifiers Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 17
Performance: Gain fluctuations Correlation with voltage fluctuations 1 Hz n n n Fluctuations of gate voltage measured with HP 35670 A Moderate correlation with gain fluctuations for different amplifiers measured at the same bias point This simple DC measurements may be useful for pre-selecting least fluctuating devices from a batch Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) 1 Hz Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 18
Performance: Gain fluctuations Bias dependence n Tested the variation of gain and voltage fluctuations with drain voltage l l n n Found a steep change in gain voltage around 0. 5 V The behaviour of gain and voltage fluctuations is similar as Vd varies High fluctuation zones could be avoided with no penalty in noise or gain Voltage fluctuations may help detecting these bias regions Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 19
Performance: Isolators Impact in overall performance n Isolators measured @ 14 K (PAMTECH gives data @ 77 K) Good agreement between measurement and estimation of isolator noise: n Mean contribution 1. 1 – 1. 4 K n Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 20
Performance: Isolators Results Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 21
Summary n 34 In. P HEMT 4 -8 GHz cryogenic amplifiers fabricated for HERSCHEL, including the Development Models with TRW transistors n Cryogenic S parameters of In. P transistors measured in microstrip and noise models developed n Cryogenic isolators used at the input allow wide-band mixerindependent design with small penalty in noise n Exceptional performance and repeatability For the final DMs 3. 5 K noise and 27± 1. 1 d. B gain dissipating 4 m. W n Gain fluctuations exhibit a greater dispersion l n Low frequency noise of gate bias may help selecting more stable devices High sensitivity of gain fluctuations to bias point l Gate bias noise measurements could detect bias regions of high fluctuations Centro Astronómico de Yebes, Obs. Astronómico Nacional, IGN (Spain) Astronomical Telescopes and Instrumentation (SPIE) 8/28/02 22
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