G. P. Li

Broad-band power amplifier with a novel tunable output matching network

A multiband power amplifier module (PAM) comprised of an InGaP/GaAs heterojunction bipolar transistor (HBT) monolithic microwave integrated circuit (MMIC) broad-band power amplifier (PA) and a tunable multiband output matching circuit is proposed and demonstrated. The three-stage MMIC broad-band PA is realized by using the novel HBT structure and layout, applying broad-band and compensating matching technique in matching network design, adopting power gain predistortion at the first stage, and optimizing the distribution of power gain among stages. The output matching circuit is implemented with parallel inductance-capacitance (LC) tank circuits using p-i-n diodes to control the inductor value. This multiband PAM offers advantages of tunable frequency band, low insertion loss, small size, and high linearity. The multiband PAM biased at 3.5 V demonstrates 27-dB power gain, 30-dBm output power, and higher than 40% power-added efficiency at frequencies covering dual bands from 0.85 to 0.95 GHz and from 1.71 to 1.95 GHz.

A novel on-chip ESD protection circuit for GaAs HBT RF power amplifiers

A low capacitance, on-chip Electrostatic Discharge (ESD) protection circuit for GaAs power amplifiers that does not degrade RF circuit performance is introduced. Its principle of operation, capacitance loading, leakage current, ESD clamping characteristics, and robustness over process variation and temperature will be presented. Finally, a case study of its application to wireless local area network 11.802A, 5.8GHz power amplifier will be discussed.

A novel tunable broadband power amplifier module operating from 0.8 GHz to 2.0 GHz

In this paper, an InGaP/GaAs HBT broadband power amplifier with a novel tunable output matching circuit is first proposed and implemented. The 3-stage broadband power amplifier is realized by using the compensating matching technique and optimizing the distribution of power gain among stages. The output matching circuit is implemented with parallel L/spl I.bar/C tank circuits using PIN diodes to control the inductor value. This broadband amplifier module offers the advantage of fewer components, less power insertion loss, small size and high linearity. The broadband power amplifier module demonstrates 28 dB power gain, 30 dBm output power and higher than 30% power added efficiency (PAE) at frequencies covering dual bands from 0.85 GHz to 0.95 GHz and from 1.71 GHz to 1.95 GHz, which can be used in the GSM, DCS, PCS and CDMA systems.

InGaP/GaAs HBT RF power amplifier with compact ESD protection circuit

A 5.4-6.0 GHz InGaP/GaAs HBT power amplifier with a compact 2000 Vesd on-chip electrostatic discharge (ESD) protection circuit that has low loading capacitance of less than 0.1 pF and does not degrade RF and output power performance is presented for wireless LAN application. In contrast to the traditional diode string, a diode triggered Darlington pair is implemented as the ESD protection circuit. This summary discusses the operation principle, ESD protection performance and RF loading of the ESD protection circuit, and the power amplifier performance with this ESD protection circuit.

InGaP/GaAs HBT DC-20 GHz distributed amplifier with compact ESD protection circuits

This paper presents design considerations and implementation of InGaP/GaAs HBT DC-20 GHz distributed amplifier with compact ESD protection circuits. The inherit benefits of both bandwidth and ESD robustness of distributed amplifiers are first compared to those of single-ended feedback amplifiers. Next, novel on-chip ESD protection circuits are introduced, featuring low capacitance loading for wide bandwidth, low leakage, and good linearity under high RF power. This paper discusses the principle of operation and performance of the ESD protection circuits, and the RF loading to the distributed amplifier. The RF performance and ESD robustness of the distributed amplifier are also discussed.

A novel compact composite power cell for high linearity power amplifiers in InGaP HBTs

A novel compact composite power cell design employing the circuit feedback concept between the input and output ports of the power transistor is proposed for realizing high linearity and high efficiency power amplifiers. The RF performance is compared between conventional and the novel compact composite power cells using a class A amplifier operating at 1.71 GHz. At the same DC biasing conditions, the composite power cell shows the output power 1 dB compression point improvement over a conventional cell from 18dBm to 23dBm, while its power added efficiency at P1dB point is increased to 47% from 16%. Furthermore, the third order intercept point of the composite transistor PA achieves 7 dB improvement over the conventional PA, from 29 dBm to 36 dBm.

A GaAs HBT programmable linear power amplifier

A three-stage power amplifier with a novel programmable linearization input stage is proposed and designed. The input stage with dual feedback loops can predistort the input signal to compensate the gain compression and phase distortion attributed from the following stages. The power amplifier demonstrated a peak PAE of 62% at the output power of 30.5dBm operating at 1.75GHz to 1.95GHz. At 27dBm output power level the adjacent channel power rejection ratio (ACPR) is less than -44dBc at a 1.25MHz offset frequency.

A Novel High Efficiency and Linearity Power Amplifier with Over-Voltage Protection

This paper presents a power amplifier (PA) design to improve linearity by using a novel power cell compensating the main nonlinear sources from the power devices and to improve the overall efficiency by a dynamic DC biasing circuit. An over-voltage protection circuit to ease output mismatch induced problems is included in this PA design. As a case study, this power amplifier is implemented with InGaP/GaAs HBT operating at 1880 MHz. The CDMA standard is used to evaluate its linearity and efficiency. The P1dB is improved from 30 dBm to 32 dBm and the cumulated output current is much improved in a wide output power range. The ACPR and ALTR at 28 dBm output power level are improved by 5 dB and 12 dB with the novel PA respectively. The over-voltage protection circuit works well under output mismatch conditions.