21ST INTERNATIONAL SYMPOSIUM ON SPACE TERAHERTZ TECHNOLOGY, OXFORD, 23-25 MARCH, 2010 A 530-600 GHz silicon micro-machined integrated receiver using GaAs MMIC membrane planar Schottky diodes B. Thomas 1 , C. Lee 1 , A. Peralta 1 , J. Gill 1 , G. Chattopadhyay 1 , S. Sin 1 , R. Lin 1 and I. Mehdi 1 1 NASA- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, PASADENA, CA, 91101, USA. Email: Bertrand.C.Thomas@jpl.nasa.gov Abstract— We present here a novel integrated receiver architecture called Radiometer-On-a-Chip (ROC) that uses a combination of MMIC amplifier, GaAs Schottky multiplier and mixer devices and silicon micro-machining techniques. The novel stacking of micro-machined silicon wafers allows for the 3-dimensional integration of the W-band power amplifier, a 280 GHz tripler and a 560 GHz sub-harmonic mixer in an extremely compact package. Preliminary results give a DSB mixer noise temperature of 4860 K and DSB mixer conversion losses of 12.15 dB at 542 GHz. Instantaneous 3 dB RF bandwidth extends from 525 to 585 GHz. To the authors' knowledge, this is the first demonstration of an all integrated silicon micro-machined receiver front-end at these frequencies. INTRODUCTION The sub-millimeter wave range (300 GHz – 3 THz) is rich in emission and absorption lines of various molecular species (i.e. CH4, CO, H2O, HCN, etc…) whose detection and mapping are important to understand the atmospheric circulation of telluric planets (Venus, Earth, Mars), outer planets (Jupiter, Saturn) and their moons (i.e. Europa, Titan). Sub-millimeter wave spectrometers with very high spectral resolution have been flown for Earth remote sensing up to 2.5 THz. However, their use in planetary exploration has been severely restricted due to their large mass and power requirements. Conventional approach prevents them from fitting in the mass and power budgets of most platforms. To tackle that problem, we present here a novel Radiometer- On-Chip (ROC) architecture that uses a combination of GaAs MMIC Schottky diodes and silicon micromachining techniques. Due to the unique arrangement of actives components together with silicon micro-machined waveguide structure in a stacked configuration, three-dimensional radiometer circuits can now be conceived and are presented here. First, a W-band amplifier module based on this technology utilizing pHEMT based MMICs has been designed, fabricated and tested. The design of the Si-packaged amplifier is shown here. Second, the development of an integrated 530-600 GHz silicon micro- machined ROC is discussed later. The 530-600 GHz ROC features an integrated 265-300 GHz tripler and 530-600 GHz sub-harmonic mixer based on MMIC GaAs membrane planar Schottky diodes. Preliminary measurement results are presented. This novel approach allows the reduction of the heterodyne receiver front-end elements (Local Oscillator generation based on frequency multiplication/amplification, sub-harmonic and/or fundamental mixers, IF Low Noise Amplifiers and DC bias circuits) by an order of magnitude in mass compared to conventional metal milling. ROC ARCHITECTURE CONCEPT The ROC architecture is based on the stacking of Silicon micro-machined wafers together with MMIC GaAs devices, and is shown in Fig.1. Two stages can be identified: the 1 st one including components operating at W-band and the second one for the 300-600 GHz components. The first stage is made of the 1 st and 2 nd Si-layer. It includes a W-band Power Amplifier (PA) MMIC device in between. The 2 nd wafer also act as a spacing layer between the first stage (PA) and the third stage. The second stage is made of the 3 rd and 4 th Si-layer. It includes a 265-300 GHz MMIC GaAs membrane Schottky tripler and a 530-600 GHz MMIC GaAs membrane Schottky sub-harmonic mixer in between. Each layer interfaces with the next one through waveguides opening on the flat of the Si wafers. The LO signal is input via a W-band input waveguide. The RF signal is input via an RF feed-horn. The IF signal is output via a micro-coaxial connector on the top of the 4 th layer. Fig.1. Radiometer-On-a-Chip concept, including an input W-band waveguide, a W-power amplifier stage, an integrated 300 GHz tripler - 600 GHz sub-harmonic mixer stage, and a 600 GHz RF feed-horn antenna. Although this approach is meant to integrate both stages at the same time, each stage has first been designed and implemented individually in order to characterize them separately. Therefore, in the following sections, additional Si-layers are used for each stage in order to interface them with standard metal waveguide flanges required for testing. 1 st W-band PA stage Spacer 2 nd sub-mm tripler/ mixer stage W-band input LO waveguide IF output & RF antenna layer RF feedhorn antenna 161