Shingo Yamanouchi

A diplexer-matching dual-band power amplifier LTCC module for IEEE 802.11a/b/g wireless LANs

We have developed a compact dual-band (2.4/5 GHz) power-amplifier module with a concurrent two-stage InGaP/GaAs HBT for triple-mode (IEEE 802.11a/b/g) WLANs. The proposed diplexer-matching network is three-dimensionally implemented in an LTCC substrate (5/spl times/5 mm). The module exhibits an output power of 20 dBm at 2.4 GHz, and 18 dBm at 5.25 GHz with an error vector magnitude of 4-5% for a 54-Mbps OFDM signal. Our approach of using a concurrent dual-band PA reduces the size and cost by almost half compared with using a conventional parallel PA.

An efficient algorithm for simulating error vector magnitude in nonlinear OFDM amplifiers

We have developed an algorithm for evaluating the error vector magnitude (EVM) from the single-tone distortion of power amplifiers in orthogonal frequency-division multiplexing (OFDM) systems. The developed formulas allow us to simulate EVM using only the single-tone response i.e. without modulation and demodulation; this enables us to easily calculate the EVM using a standard harmonic-balance (HB) simulator. This simulation scheme reduces the processing time by a factor of ten compared with conventional system-level (SL) simulation. The EVM obtained using this scheme agreed well with the results of SL simulation (0.6% error).

An envelope tracking power amplifier using an adaptive biased envelope amplifier for WCDMA handsets

An envelope tracking power amplifier (ET-PA) using a self-oscillation pulse-width-modulation circuit with an adaptive bias technique is presented. In this technique, the supply voltage to the envelope amplifier is changed depending on the output power level. Since this approach enables the envelope amplifier to change the output power without degrading the signal resolution, the developed ET-PA shows a low adjacent channel leakage power ratio (ACPR) of less than -38 dBc in a wide output power range from 10 to 27 dBm. The ET-PA shows 45.4% overall efficiency at peak output power of 28 dBm. The average efficiency was 29%, which is 2.4 times higher than that of a class-AB PA. The noise power in the receive band (Rx noise) is -136 dBm/Hz at output power of 26 dBm at a frequency of 2.14 GHz.

Analysis and Design of a Dynamic Predistorter for WCDMA Handset Power Amplifiers

This paper presents a dynamic predistorter (PD), which linearizes the dynamic AM-AM and AM-PM of a wideband code division multiple access handset power amplifier (PA). The dynamic PD allows an adjacent channel leakage power ratio (ACPR) improvement of 15.7 dB, which is superior to conventional PDs that linearize static AM-AM and AM-PM. The dynamic PD was designed using an HBT generating nonlinearity, a short circuit at the baseband (les4 MHz), and a load circuit for the HBT at the RF fundamental band (ap1.95 GHz). Volterra-series analysis was performed to understand the mechanism of the dynamic PD. The analysis revealed that the short circuit at the baseband enabled the dynamic PD generating third-order intermodulation distortion (IMD3) with opposite phase to the fundamental tone (i.e., antiphase IMD3). The antiphase IMD3 allows dynamic gain compression, which linearizes the dynamic gain expansion of a PA with low quiescent current. The analysis also revealed that the IMD3 amplitude of the dynamic PD can be adjusted by load impedance at the RF fundamental band, which enables the gradient of dynamic AM-AM and AM-PM to be optimized to linearize the PA. The fabricated two-stage InGaP/GaAs HBT PA module with the dynamic PD exhibited an ACPR of -40 dBc and a power-added efficiency of 50% at an average output power of 26.8 dBm with a quiescent current of 20 mA

A 0.04 cc Power Amplifier Module with Fully Integrated Passives in a Hybrid LTCC Substrate for 5-GHz Wireless LANs

A compact power amplifier (PA) module using a novel hybrid low-temperature co-fired ceramic (LTCC) substrate has been developed for 5-GHz wireless LANs (WLANs). Passive components were embedded in the multi-layer LTCC substrate, which was laminated with three types of dielectrics. The hybrid substrate makes it possible to reduce component area and minimize RF coupling among the components. These improvements allowed us to integrate matching and bias networks within a compact 5 × 5 × 1.4 mm3 (= 0.04 cc) module size. The PA module was accurately designed using a passive component library developed based on EM (electromagnetic) simulation. The fabricated module exhibited power performance sufficient for 5-GHz WLANs, i.e., - linear gain of 25 dB and output 1-dB compression power (P1dB) of 21 dBm with power added efficiency (PAE) of 19%. This is the first report of a PA module with fully embedded matching networks in an LTCC substrate for 5-GHz Wireless LANs.

A 72% PAE, 95-W, single-chip GaN FET S-band inverse class-F power amplifier with a harmonic resonant circuit

This paper describes a high-efficiency, high-output-power GaN power amplifier for S-band radar applications. The amplifier uses an inverse class-F configuration for high efficiency. The matching circuit includes a 2nd harmonic resonant circuit to compensate for GaN FET parasitics. The developed GaN single-chip power amplifier delivers output power of 95 W with power added efficiency (PAE) of 72% and high linear gain of 19.8 dB at 2.6 GHz. To the best of our knowledge, this is the highest efficiency for S-band power amplifiers ever reported with nearly 100-W output power.

A 0.08-cc fully integrated LTCC transceiver front-end module for 5-GHz wireless LAN systems

An extremely compact transceiver (TRx) front-end module (FEM) has been developed for 5-GHz wireless LAN systems. A highly-integrated flip-chip TRx IC and the embedding of passive devices in a low-temperature co-fired ceramic (LTCC) with high /spl epsi//sub r/(=17) are the keys to reducing the module size to 8 /spl times/ 10 /spl times/ 1 mm (0.08 cc). To the best of our knowledge, this is the most compact existing FEM that demonstrates full transceiver operation and complies with the IEEE 802.11a standard.

A Polar Transmitter Using a Linear-Assisted Delta-Modulation Envelope-Amplifier for WCDMA Applications

A polar transmitter using a new linear-assisted delta-modulation (LADM) envelope-amplifier has been developed for WCDMA applications. The LADM system is composed of a highly efficient switching block based on a 200-MHz-clock delta-modulator, which is implemented in a 0.18-mum CMOS IC, and a highly accurate linear block. In the LADM approach, the residual quantization noise and distortion of switching amplification are removed through the assistant linear process; thus, a sufficiently low ACPR of -45 dBc and a small EVM of 1.7% can be achieved without a pre-distortion technique. The developed polar transmitter nearly doubles the average efficiency in the 10- to 15-dB back-off region of class-AB PAs

OFDM error vector magnitude distortion analysis

We derived explicit formulas for evaluating the error vector magnitude (EVM) from the amplitude distortion (AM-AM) and phase distortion (AM-PM) of power amplifiers (PAs) in orthogonal frequency-division multiplexing (OFDM) systems, such as the IEEE 802.1 1a/g wireless local area networks (WLANs) standards. We demonstrated that the developed formulas allowed EVM simulation of a memoryless PA using only a single-tone response (i.e. without OFDM modulation and demodulation), thus enabling us to easily simulate the EVM using a harmonic-balance (HB) simulator. This HB simulation technique reduced the processing time required to simulate the EVM of a PA for the IEEE 802.1 1a standard by a factor of ten compared to a system-level (SL) simulation. We also demonstrated that the measured EVM of a PA module for the IEEE 802.11g could accurately be predicted by applying the measured static AM-AM and AM-PM characteristics to the derived formulas.

50% PAE 20-mA quiescent current W-CDMA power amplifier with on-chip dynamic-gain linearizer

This paper explains a power-effective linearization technique for power amplifiers (PAs) having gain-expansion characteristics. A new on-chip dynamic-gain-deviation cancellation circuit improves the adjacent-channel-leakage-power ratio (ACLR) for a W-CDMA signal by 11 dB. At a supply of 3.5 V and an output power of 26.9 dBm, a fabricated PA with a quiescent current (Iq) of 19 mA exhibited a power-added efficiency of 50%, a gain of 26 dB, and an ACLR of -40 dBc. Furthermore, when we applied this technique to a PA with Iq of only 10-mA, this PA also satisfied the W-CDMA criteria.