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Superconducting Integrated Receiver for TELIS: optimization and computer control
Andrey Ermakov12, Valery Koshelets12, Oleg Kiselev1, Pavel Yagoubov2, Gert de Lange2 , Bart van Kuik2
2 1Institute of Radio Engineering and Electronics, IREE, Russia SRON Netherlands Institute for Space Research, the Netherlands

Abstract
The Superconducting Integrated Receiver (SIR) contains a few interactive devices: SIS mixer integrated in planar antenna, a superconducting phase-locked Flux Flow Oscillator (FFO) acting as a Local Oscillator (LO), harmonic mixer (HM) for the FFO phase locking. DAQ system IRTECON was created for fast testing and control this complex device. IRTECON system makes it possible to collect data for all internal SIR devices and the SIR as a unit, to create specific measurement procedures, to optimize operational characteristics and to provide real-time SIR control. Special procedures had been developed and tested with the flight electronics: · fast definition of the operational conditions for the FFO (both in the Fiske step and quasi-particle regimes); · measurements of the free-running FFO linewidth; · optimization of the LSU and HM parameters; · optimization of the PLL operation; · minimization of the SIR noise temperature; · setting all predefined SIR parameters in the exact sequence for flight (with checking and adjustments); · continuous monitoring of the main SIR parameters, adjustment (or recovering) the SIR operational state; The flight version of the program has been created for remote control of the TELIS-SIR in flight. Base algorithms were translated in macros for effective remote SIR control.

Superconducting Integrated Receiver
4 K dewar SIR chip
SIS mixer Harmonic mixer FFO as LO 550-650 GHz 20 GHz reference

HEMT 4-8 GHz

IF Processor & DAC

Computer controlled data acquisition system Electronics FFO, SIS, HM control

Choosing LSU frequency. Green curve ­ the best one. FFO frequency = 619.1 GHz

HEMT
4 GHz

PLL
Schematics of the FFO the 19-21 GHz referenc compared with the 400 generated by

LSU

400 MHz reference

stabilization circuit. FFO frequency is mixed in HM with e. The mixing product is amplified, down converted and MHz reference in the PLL. The phase difference signal PLL is used to feedback the FFO control line.

SIS IF dependence on HM voltage and LSU power. FFO frequency = 619.1 GHz, LSU frequency = 20.77 GHz

Repeatability of the SIS and the FFO characteristics.

Two FFO I-V curves at the same magnetic current 53 mA after thermal cycle. IV-curves of FFO at different magnetic fields. A color scale indicates the regions in which photon-induced current of SIS-mixer is sufficient for receiver operation (the red color means the larger value of the induced current).
12 10

PLL IF dependence on HM voltage and LSU power. FFO frequency = 619.1 GHz, LSU frequency = 20.77 GHz

FFO linewidth, Hz

8 6 4 2 0

a)

Dependence of the SIS Ic (New CL). Left ­ picture of "normal" Ic suppression, right - Ic suppression for a SIS with trapped magnetic flux

1,030

1,032

1,034

1,036

1,038

FFO voltage, mV

Fiske step regime, FFO frequency of about 500 GHz

b)

Dependencies of the IF output signal on the HM bias voltage and synthesizer power: a) LSU frequency 19.72 GHz, FFO frequency = 497 GHz; b) LSU frequency - 20.46 GHz, FFO frequency = 495 GHz

Summary
The complex DAQ system "IRTECON" has been created; The set of procedures for optimization of main SIR regimes has been developed and experimentally proven; The algorithms to adjust and recover the SIR state have been created; The flight program for remote SIR control has been developed; For information please contact: ermakov@hitech.cplire.ru ISSTT 2008 The Netherlands.