No abstract

No abstract

A novel extraction method to estimate the thermal resistance (R th ) of a multifinger GaAs heterojunction bipolar transistor (HBT) device is presented based on the simplified Fourier's law. By calculating the thermal coupling resistance between the fingers on top of the self-heating thermal resistance, the values of R th of multifinger devices for various dimensions are accurately calculated while maintaining the simplicity of calculation. To verify the idea, the proposed method is compared with the measurement-based method as well as the analytic methods, such as the finite-element method and the solution of 3-D Laplace's equation. For four-finger HBT devices, the extracted R th results showed good agreements with the analytic methods within an error of 9% and the measurement-based results with a deviation of 7.4%, thus convincing the usefulness of the proposed method.

No abstract

A linearization technique based on the phase correction is proposed for a CMOS stacked-FET power amplifier (PA). The linearizer employs a phase injection circuit as a main linearizer. The phase injection circuit presents envelope-reshaped capacitance to the gate of a driver amplifier to correct for phase compression near saturation. It also helps with AM-AM linearization. Hybrid bias circuit consisting of a diode and a resistor is also employed for static adaptive biasing, which allows the PA to meet stringent linearity requirement across the entire power range. Two stacked-FET linear PAs with the proposed linearizers have been designed using a silicon-on-insulator (SOI) CMOS process at 1.88 and 0.9 GHz. The fabricated PAs show adjacent channel leakage ratios (ACLRs) better than with peak power-added efficiencies (PAEs) of 44.3 and 49.2% at 1.88 and 0.9 GHz, respectively, using 3GPP uplink W-CDMA signal.

Fully-integrated multi-mode multi-band (MMMB) reconfigurable power amplifier (PA) is implemented using single PA-cores for high-and low-frequency bands, respectively. This PA has five output paths and covers quad-band Gaussian Minimum Shift Keying/Enhanced Data Rates for Global Evolution and penta-band Universal Mobile Telecommunications System/Long Term Evolution mode operation with band combination in a small form-factor. To optimize the PA, the proposed structure reconfigures the PA-core cells as well as the interstage/output matching network. When compared with the single-mode single-band dedicated PAs, the fabricated PA showed comparable RF performance for all modes and bands, except for PAE degradations of 3.1% and 1.9% for high-and low-band, respectively, thus validating the usefulness of the proposed structure for MMMB PA applications.Index Terms-Multi-band, multi-mode, penta-band UMTS/ LTE, quad-band GMSK/EDGE, reconfigurable power amplifier (PA), single PA-core.

In this paper, a two-stage broadband CMOS stacked FET RF power amplifier (PA) with a reconfigurable interstage matching network is developed for wideband envelope tracking (ET). The proposed RF PA is designed based on Class-J mode of operation, where the output matching is realized with a two-section low-pass matching network. To overcome the bandwidth (BW) limitation from the high-interstage impedance, a reconfigurable matching network is proposed, allowing a triple frequency mode of operation using two RF switches. The proposed RF PA is fabricated in a 0.32-m silicon-on-insulator CMOS process and shows continuous wave (CW) power-added efficiencies (PAEs) higher than 60% from 0.65 to 1.03 GHz with a peak PAE of 69.2% at 0.85 GHz. The complete ET PA system performance is demonstrated using the envelope amplifier fabricated on the same process. When measured using a 20-MHz BW long-term evolution signal, the overall system PAE of the ET PA is higher than 40% from 0.65 to 0.97 GHz while evolved universal terrestrial radio access adjacent channel leakage ratios are better than 33 dBc across the entire BW after memoryless digital pre-distortion. To our knowledge, this study represents the highest overall system performance in terms of PAE and BW among the published broadband ET PAs, including GaAs HBT and SiGe BiCMOS.Index Terms-Broadband, class-J, CMOS, envelope tracking (ET), high-efficiency, long-term evolution (LTE), multiband, power amplifier (PA), silicon-on-insulator (SOI), stacked FET.

Ultra small-size power amplifier (PA) modules were developed for WCDMA handset applications. To reduce the size of the PA modules, the bulky transmission lines and lumped surface mountable chip elements of the conventional output matching network (OMN) were replaced with the proposed helix-on-pad (HoP) and an integrated passive device (iPD), respectively. Three 2 mm 2 mm single-band PA modules were developed using the proposed OMNs for UMTS Band-5, Band-1, and Band-2 applications. No RF performance degradation was observed from the size-reduced PA modules. For the demonstration of ultimate size reduction, a dual-band PA for UMTS Band-2/ Band-5 application was developed in a 3 mm 3 mm form-factor. The PAs exhibited adjacent channel leakage ratios (ACLRs) better than 38 dBc over the entire output power range together with power-added efficiencies (PAEs) in excess of 39% at 28.5 dBm. Besides, the PAs showed good low-power efficiency of 16% at out = 16 dBm due to the stage-bypass architecture. The proposed method can be applied in a variety of wireless Tx applications requiring small form-factors and high efficiencies.Index Terms-Efficiency, helix-on-pad, integrated passive device, power amplifier (PA), small size, WCDMA.