A Wideband, Dual-Path, Millimeter-Wave Power Amplifier With 20 dBm Output Power and PAE Above 15% in 130 nm SiGe-BiCMOS

Abstract

A frequency-scalable, three-stage, transformercoupled millimeter-wave power amplifier (PA) is implemented in 130 nm SiGe-BiCMOS. Differential common-base gain stages extend collector-emitter breakdown voltage beyond 3 V, while collector-emitter neutralization increases reverse isolation and stability. Monolithic self-shielded transformers designed for low insertion loss and compact dimensions on-chip include: a 2:4 input power splitter, a 4:1 output balun combiner and inter-stage coupling transformers. The balun combiner and fully-differential splitter are compensated for imbalances caused by parasitic interwinding capacitance, and simulations predict better than 3% uniformity between reflected port-to-port impedances at 60 GHz. Simulated impedance uniformity is within 6% from 55-65 GHz, and insertion loss of the 0.015 mm combiner prototypes at 60 GHz is below 1 dB.The 0.72 mm 60 GHz-band PA realizes a measured peak smallsignal gain higher than 20 dB with over 10 GHz 3 dB bandwidth. Reverse isolation is better than 51 dB from 50-65 GHz and the PA is unconditionally stable. It consumes 353 mW (quiescent) from a 1.8 V supply and the active area is 0.25 mm . Maximum output power and peak power-added efficiency (PAE) are 20.1 dBm and 18% at 62 GHz, respectively. An up-banded 79-87.5 GHz PA is also implemented to verify frequency scalability of the design. The 0.23 mm active area 79 GHz PA prototype produces 18 dBm saturated output power and 9% peak-PAE at 84 GHz from a 2.5 V supply.

A 1.2V 20 dBm 60 GHz power amplifier with 32.4 dB Gain and 20 % Peak PAE in 65nm CMOS

“…In 65nm Bulk CMOS, deep AB-class biasing is not suitable because the transistors do not provide enough gain. Finally, this PA prototype achieves not only performances close to SiGe circuits [6], but also exhibits the highest figure of merit (FoM ITRS) reported in the silicon 60GHz power amplifiers with about 122,000. …”

“…These two structures must be carefully designed to respect electro-migration rules. Pure voltage Distributed Active Transformer (DAT) [5][6] occupies a compact area and achieves a very high efficiency without extra losses due to transformation ratio. Moreover, these structures perform balanced-to-unbalanced mode conversion.…”

Analysis and design of a high power, high gain SiGe BiCMOS output stage for use in a millimeter-wave power amplifier

“…Especially when multiple transistors are combined in parallel for high power with small spacing to ensure bias and thermal stability, this capacitor becomes large and can cause instability. The basic mechanism behind this instability is the positive feedback between collector and emitter due to this capacitor as discussed in detail in [7]. This is solved by placing a cross-coupled capacitor between the collector and emitter of the common base transistors [7].…”

“…The basic mechanism behind this instability is the positive feedback between collector and emitter due to this capacitor as discussed in detail in [7]. This is solved by placing a cross-coupled capacitor between the collector and emitter of the common base transistors [7]. However, this leads to a large shift in resonant frequency of the output impedance Z o .…”

Advances in Silicon Based Millimeter-Wave Monolithic Integrated Circuits

“…Also, this inter-stacked transformer improves the output loss owing to the differential-to-single-ended conversion. In [97], the collector-emitter breakdown beyond BVCEO is achieved with the differential common-base pairs and stability and reverse isolation are improved by the cross-coupled, collector-emitter neutralization. Furthermore, the novel transformer power combiner improves the uniformity of the load impedance while transforming to each primary port.…”