SiGe Bipolar Process Research Articles

Realization of GHz band integrated optical links in a radio frequency Si Ge bipolar process operating at 650 to 850 nm wavelength

A series of on-chip optical links of 50-μm length, utilizing 650 to 850 nm propagation wavelength, with Si avalanche-mode optical sources, silicon nitride-based waveguides, and Si Ge detectors, have been designed and realized, with a 0.35-μm SiGe radio frequency bipolar integrated circuit process. The optical coupling between the optical source and the detectors was realized by a set of dedicated designed optical waveguides, which were all fabricated with components of the SiGe radio frequency process. All components were fully integrated on the same silicon chip. The Si avalanche-mode light-emitting diodes (Si AMLEDs) emitted in the 650- to 850-nm wavelength regime. Correspondingly, small microdimensioned detectors utilize SiGe detector technology with detection efficiencies of up to 0.85 in the same wavelength regime and with a transition frequency of up to 20 GHz. Best performances for the optical links as realized show optical coupling of up to 5 GHz with a total optical link budget loss of −40 dB. A set of link results are presented and several interpretations are given on current realizations. The technology is particularly suitable for realization of low-cost on-chip optical signal processing, optical interconnects, and various types of on-chip microsensors.

SiGe Photo-Transistor for Low-Cost SSMF-Based Radio-Over-Fiber Applications at 850nm

This paper investigates the possibility of implementing SiGe Hetero-junction bipolar Photo-Transistor (HPT) within low cost and low power consumption Radio-over-Fiber (RoF) systems based on standard single mode fiber (SSMF) operating in the first optical window for wireless communication networks scenarios. The SiGe HPT under study has potential lower cost compared to standard PIN photo-detectors as it is fabricated through the consolidated SiGe bipolar transistor process technologies, allowing the possible integration with Si-based circuits. Various operation modes of the photo-transistor (such as three-terminals and two-terminals) are investigated, analyzing their impact on the SSMF-based RoF link in terms of gain and noise (including modal noise fluctuations) for a frequency range up to 2.5 GHz. A 20 MHz LTE transmission is finally demonstrated as example of possible applications of the studied RoF link.

A 1.5 V 28 GHz Beam Steering SiGe PLL for an 81-86 GHz E-Band Transmitter

This letter presents measurement results for a low supply voltage 28 GHz beam steering PLL, designed in a SiGe bipolar process with $f_{T}= 200$ GHz. The PLL, designed around a QVCO, is intended for a beam steering 81-86 GHz E-band transmitter. Linear phase control is implemented by variable current injection into a Gilbert type phase detector, with a measured nominal phase control sensitivity of 2.5 °/ $\mu \text {A}$ . The demonstrated LO generation method offers great advantages in the implementation of beam steering mm-wave transmitters, since only the low frequency PLL reference signal of 1.75 GHz needs to be routed across the chip to the different transmitters. Except for an active loop filter, used to extend the locking range of the PLL, the design uses a low supply voltage of 1.5 V. The PLL obtains a measured in band phase noise of −107 dBc/Hz at 1 MHz offset. The power consumption equals 54 mW from the 1.5 V supply plus 1.8 mW for the variable supply of the active low pass filter.

Estimation of signal attenuation in the 60 GHZ band with an analog BiCMOS passive filter

Prediction of millimeter(mm)-wave radio signals can be beneficial in recreating and repeating atmospheric conditions in a controlled, laboratory environment. A path-loss model has been proposed that accounts for free-space losses, oxygen absorption, reflection and diffraction losses, and rain-rate attenuation at mm-wave frequencies. Two variable passive low-pass-integrated circuit filter structures for attenuation in the 57–64 GHz unlicensed frequency band have been proposed, designed, simulated, prototyped in a 130-nm SiGe bipolar complementary metal-oxide semiconductor process, and measured. The filters are based on the Butterworth and Chebyshev low-pass filter topologies and investigate the possibility of using the structures to perform amplitude attenuation of mm-wave frequencies over a short distance. Both filters are designed and matched for direct coupling with equivalent circuit models of dipole antennas operating in this frequency band. Full integration therefore allows prediction of atmospheric losses on an analog, real-time, basis without the requirement of down-converting (sampling) to analyze high-frequency signals through a digital architecture. On-wafer probe measurements were performed to limit parasitic interference from bonding wires and enclosed packaging.

A SiGe HBT low noise amplifier using on-chip notch filter for K band wireless communication

In this paper a new notch filter topology has firstly been described. In order to improve the input match as well as enhance the gain on the operating frequency of 20.5GHz, extra capacitor has firstly been added in the passive base-collector notch filter forming a new scheme, eliminating the operating-frequency (op) input mismatch in formal base-collector notch filters. EM simulations have shown that the LNA obtained 14.1dB gain at 20.5GHz and high image-rejection ratio (IRR) of 33.5dB at image frequency of 15GHz, and S11 of -15dB was obtained compared to −8dB without notch filter at operating frequency, NF was below 5dB at gain peak frequency, power consumption was 18mW at 3V voltage supply, and IIP3 was 3.43dBm ensuring a high linearity in SiGe bipolar process.

A Broadband Double-Conversion RF Tuner

A prototype design of upconverter and downconverter units for a double-conversion cable-modem RF tuner are presented. The upconverter upconverts a channel from 47--862 MHz input band to around 1575 MHz intermediate frequency. The image-reject downconverter shifts the channel to 36.125 MHz (EU) or to 43.75 MHz (US). The upconverter includes a variable-gain low-noise amplifier, a double-balanced mixer, a three-stage VCO bank for LO generation and a divide-by-two circuit for driving an external PLL. The downconverter includes a LNA, image-reject mixers in Hartley configuration, a 3-stage polyphase filter, an IF-amplifier and a SAW driver. For the second LO generation the circuit includes a 6-GHz on-chip VCO, a divide-by-four circuit for quadrature LO and a divide-by-16 for feeding an external PLL. Signal reversal switching in the LO buffer can be used for the selection of LSB/USB injection. All building blocks are presented in this paper and experimental results are given from the upconverter, downconverter, and RF tuner demonstrator including SAW filters with center frequencies at 1575 and 44 MHz. The circuits are fabricated in a 0.9-? m SiGe bipolar process.

SiGe LNAs for UMTS System

Three LNAs at 2 GHz frequency range have been implemented in a SiGe Bipolar process targeted for a universal mobile telecommunications system. The LNAs are operating in two gain modes and they include a power-down mode. Both on-wafer and packaged LNAs were measured. Noise figure below 2 dB with IIP3 of 1 dBm and gain exceeding 15 dB has been achieved. LNAs work from a 2.7–5.5 V power supply. A figure of merit method is used to compare this work to other published LNAs.