Prabir K. Saha

An 8–16 GHz SiGe Low Noise Amplifier With Performance Tuning Capability for Mitigation of Radiation-Induced Performance Loss

We present a wideband, low noise amplifier (LNA) implemented in a Silicon-Germanium Heterojunction Bipolar Transistor (SiGe HBT) technology. This SiGe LNA covers a frequency range of 8-16 GHz and achieves a peak gain of 17.5 dB at nominal bias and a peak OIP3 of 15.8 dBm at 10 GHz at nominal bias. The noise figure (NF) of the LNA is 4.5-8.1 dB across band, and it nominally consumes 4 mA from a 4 V supply. Samples were irradiated with 63.3 MeV protons to proton-equivalent doses ranging from 200 krad(Si) to 2 Mrad(Si). This LNA incorporates bias control “tuning-knobs” to enable bias tuning to mitigate for RF performance loss due to total dose exposure and process variation in performance metrics. The effectiveness of the tuning “knobs” to compensate for lost post-irradiated performance was investigated. It was found that the LNA performance can be restored with the use of the tuning knobs with a performance tuning algorithm.

A 6–20 GHz Adaptive SiGe Image Reject Mixer for a Self-Healing Receiver

A wideband (6-20 GHz) Silicon-Germanium (SiGe) adaptive image-reject mixer with an intermediate frequency (IF) of 1.8 GHz is presented. The mixer can be “self-healed” to deliver consistent performance by nullifying the effects of process variations, environmental changes, or aging. Various performance metrics of the mixer can also be adapted to different specifications across multiple frequency bands. A conversion gain greater than 15 dB, an image rejection ratio (IRR) exceeding 35 dB, and an output 1-dB compression point greater than 10 dBm, were obtained in measurement. An automated self-healing procedure is developed and shown to be effective for improving the measured performance of the mixer. The mixer was fabricated in a 150 GHz peak fT, 200 nm SiGe BiCMOS process technology and consumes 215 mA of current operating off a 4 V rail.

A Theory of Single-Event Transient Response in Cross-Coupled Negative Resistance Oscillators

A theory of the circuit-based response to SET phenomena in resonant tank oscillators is presented. Transients are shown to be caused by a change in the voltage state of the circuits characteristic differential equation. The SET amplitude and phase response is derived for arbitrary strike waveforms and shown to be time-variant based on the strike time relative to the period of oscillation. Measurements in the time-domain are used to support the theory, while the frequency-domain is used to gauge potential impact on system performance. A design-oriented analysis of the relevant trade-offs is also presented.

Analysis and design of a 3–26 GHz low-noise amplifier in SiGe HBT technology

The analysis and design of a wideband silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) low noise amplifier (LNA) is presented. Resistive shunt-shunt feedback is employed to achieve wideband gain and matching characteristics and it is shown that the addition of small reactive elements can extend the bandwidth of the amplifier significantly. Measured data for the LNA, implemented in a 130-nm SiGe BiCMOS technology, show 9 dB gain with less than 1.0 dB variation across 3-26 GHz, and input and output return losses better than -10 dB over the entire bandwidth. The measured noise figure (NF) is less than 5 dB from 3-18 GHz and rises to only 6.5 dB at 24 GHz. In addition, the amplifier exhibits excellent linearity performance, with a input-referred third-order intercept point (IIP3) of 5.8 dBm and input-referred 1 dB compression point (P1dB) of -5.6 dBm. This SiGe amplifier occupies 0.48 mm2 (including pads) and consumes 33 mW of power while operating off a 3.3 V supply.

Evaluating the Effects of Single Event Transients in FET-Based Single-Pole Double-Throw RF Switches

The impact of single event transients (SETs) on single-pole double-throw (SPDT) RF switch circuits designed in a commercially-available, 180 nm second-generation SiGe BiCMOS (IBM 7HP) technology is investigated. The intended application for these SPDT RF switches requires a 1 GHz to 20 GHz band of operation, relatively low insertion loss (<; 3.0 dB at 20 GHz), and moderate isolation (> 15 dB at 20 GHz). Two-photon absorption experiment results reveal that the SPDT switches are vulnerable to SETs due to biasing effects as well as the triple-well (TW) nFETs, which are found to be more sensitive to SETs than bulk nFETs. From these results, potential implications are discussed and mitigation strategies are proposed. To verify one of the proposed mitigation techniques, SPDT switches were also designed in a 180 nm twin-well SOI CMOS (IBM 7RF-SOI) technology. A different biasing technique is implemented to help improve the SET response. The fabricated SOI SPDT switches achieve an insertion loss of <; 1.04 dB at 20 GHz and > 21 dB isolation at 20 GHz. For this circuit, no transients were observed even at very high laser energies (≈ 5 nJ).

A SiGe 8–18-GHz Receiver With Built-In-Testing Capability for Self-Healing Applications

A wideband (8-18 GHz) built-in test receiver in silicon-germanium technology is presented. The receiver chain consists of a low-noise amplifier (LNA), an image-reject mixer, on-chip automatic gain control ring oscillator sources that are used to provide test signals of a predefined amplitude, and control circuitry in the form of digital-to-analog converters and data registers. Both the LNA and the mixer circuit blocks incorporate tuning knobs to enable tuning of RF metrics to ensure consistent performance and mitigate the negative effects of process, voltage, and temperature variations, aging, and damage from extreme environments such as ionizing radiation. A maximum post-healed gain greater than 30 dB, an image rejection ratio exceeding 30 dB, output third-order intercept point greater than 8 dBm, and noise figure less than 9 dB are obtained in measurement. An automated healing algorithm was developed and shown to be effective at improving the overall performance of the receiver. The receiver was fabricated in an 0.18- μm SiGe BiCMOS process with a peak fT of 150 GHz, and consumes 240-260 mA from a 4-V supply.

Mixed-mode stress degradation mechanisms in pnp SiGe HBTs

An investigation of the high-voltage/high-current mixed-mode (M-M) stress-induced damage mechanisms of pnp silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) is presented. Different accelerated stress methods, including mixed-mode stress, reverse emitter-base (EB) stress, and forward collector plus reverse EB stress, were applied to pnp SiGe HBTs from a state-of-the-art complementary-SiGe BiCMOS process technology platform. The operative damage mechanism from the M-M stress method is identified. Experimental evidence of collector current change due to the M-M stress, and the experimental proof of the type of hot carriers (electrons vs. holes) responsible for the observed M-M stress damage are presented.

A tunable, SiGe X-band image reject mixer

A SiGe 8–12 GHz image reject mixer with tunable performance is presented. Control voltages and currents allow the mixer performance to be “healed”, nullifying effects of process variation or environmental changes. Conversion gain greater than 10 dB and output P1dB greater than 0 dBm were obtained in measurement. An image rejection ratio (IRR) of greater than 40 dB was obtained after tuning, a 25 dB improvement over pre-tuned results. The mixer was fabricated in a 150 GHz peak fT SiGe BiCMOS process and consumes 200 mA of current operating on a 4 V rail.

Low-loss, wideband SPDT switches and switched-line phase shifter in 180-nm RF CMOS on SOI technology

Low-loss, wideband (DC to 40 GHz) single-pole double-throw (SPDT) RF switches implemented in a 180 nm SOI CMOS technology are presented. A π-matching network is implemented to improve the insertion loss (IL) at high frequencies. The differences between the conventional inductive peaking and the matching network utilized here are discussed. Under nominal conditions, the IL of the 1.5 V switch is less than 0.5 dB from DC to 20 GHz; and less than 2.0 dB at 40 GHz. The input matching of the switch is better than 10 dB, the isolation (ISO) is greater than 15 dB, and the P1dB of the 1.5 V switch is 11 dBm. A higher voltage (2.5 V) switch implemented with high-breakdown devices increases the P1dB to 15 dBm at the cost of a small increase in IL. A switched-line one-bit 180° phase shifter (PS) is demonstrated using the 1.5 V low-loss switch. The PS exhibits an IL better than 3 dB at 18 GHz. The advantages of implementing a low-loss switch in a 180 nm technology are discussed.

A UWB SiGe LNA for multi-band applications with self-healing based on DC extraction of device characteristics

We present an ultra-wideband, Low Noise Amplifier (LNA) implemented in a Silicon-Germanium Heterojunction Bipolar Transistor (SiGe HBT) technology. This SiGe LNA covers a frequency range of 8–18 GHz and achieves a peak gain of 15.6 dB at nominal bias and a nominal OIP3 of 3 dBm at 13 GHz. The Noise Figure (NF) of the LNA is 3.6–7.9 dB across band, and it consumes 7 mA from a 3.3 V supply. This LNA incorporates bias control knobs for circuit ‘self-healing’ to compensate for process-induced (or other) variations in performance metrics. Process variations are detected using a companion source measure unit (SMU) test circuit that gathers DC device information to determine the healing to be applied.